JP2000293395A - Serial communication equipment, its abnormality detecting method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain serial communication equipment capable of easily and also accurately performing abnormality diagnosis due to wrong transmission such as noise and to obtain its abnormality diagnosing method and a recording medium. SOLUTION: Since a slave station request flag is set in a step S14 when a communication request signal from a slave station is turned on regardless of the existence/ absence of a communication request in a master station, the processing proceeds to a step S17, the content of a high order 4-bit part storing return information from the slave station which is temporarily moved and is before executing normal communication is compared with the content of a low order 4-bit part obtained by updating the return information from the slave station after executing the normal communication for each bit, and in a step S18, whether or not the whole information coincides is discriminated. When the whole information coincides in this discrimination as a result of comparing the information content, because there is discrepancy in a communication request signal generated by the update of the slave station information content, it is considered that noise, etc., is entered in a slave station communication request signal or shift transfer, and information exchange by normal communication is diagnosed as failure and made ineffective.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial communication device, a method for detecting an abnormality thereof, and a recording medium.
The present invention relates to a serial communication device for exchanging information between a master station in an apparatus and a plurality of slave stations scattered in the apparatus, a method for detecting an abnormality thereof, and a recording medium.

[0002]

2. Description of the Related Art Conventionally, a serial communication device in a device has a main device for serial communication called a master station of a central processing unit of the device and a slave station having a plurality of electric units scattered in the device. Exchanges information with a serial communication sub-device called
It is used in many devices for the purpose of suppressing the cost of the device and the ease of assembling the device.

[0003] Basically, in an information exchange configuration in a serial communication device, serial communication is performed in response to an information exchange request generated by a master station included in a central processing unit (CPU) of the device. In addition, the information exchange request from the slave station updates the information from the slave station by executing the serial communication as described above by the master station that has received the communication request signal, whereby both information exchanges are performed. .

[0004] This information exchange is performed by the master station and the slave station on a one-to-one basis. Transfer information originating from the master station is transferred to a specific slave station, and transfer information returned from the slave station is transmitted. It is necessary that the master station and the slave station recognize each other that the information is from the slave station that can be identified by the master station. For this reason, many conventional serial communication devices are configured to transfer the transfer information with identifier information designating a slave station attached thereto. This method is established after limiting the maximum number of slave stations that can be connected to the transmission path. A communication protocol and a data processing means thereof, in which the number of information bits transferred to one slave station and the number of identifier information bits are a set, and the data length configuration of the number of slave stations that can exist on the transmission path is a basic condition for transfer. Is designed. Therefore, in a serial communication device that employs such a method, a communication protocol and its data processing means are designed in consideration of a large number of slave stations in order to determine the number of slave stations that can be connected in advance. This was disadvantageous in view of cost. Further, even when the design is changed in accordance with the configuration of the number of slave stations of the entire device to be used, the basic configuration of the data length to be transferred is changed, so that at least the data processing means is redesigned. .

Therefore, in recent years, while the number of information bits transferred to one slave station and the number of identifier information bits are fixed,
A serial communication device comprising a communication protocol and a data processing means for connecting a semi-infinite number of slave stations has appeared. Thereby, regardless of the configuration of the number of slave stations of the entire device using the serial communication device,
The same serial communication device can be used with the optimum number of slave stations, and it is possible to easily cope with a design change in the middle. Naturally, the cost of the serial communication device can be reduced to the number of slave stations required by the entire device, so that the cost is reduced as compared with the conventional serial communication device. Hereinafter, a configuration of a serial communication device that can connect a semi-infinite number of slave stations while keeping the number of transfer information bits and the number of identifier information bits fixed will be described.

First, a basic configuration of serial communication will be described.

In a conventional serial communication apparatus, a master station creates a data length of transfer information, and transmits the data length of transfer information to a shift register circuit (constituting bit number of 4 bits) of each slave station together with a transfer clock. In the configuration in which the output information is shifted and transferred, by loading the shift register circuit with the slave parallel input information which is returned to the master in advance before the master performs the shift transfer, the shift transfer performed by the master is performed. This enables information exchange between the master station and each slave station.
Each slave station is configured to execute an operation specified by the count value of the phase control counter circuit that the slave station has, and the master station operates the count value of the phase control counter to shift the shift register of the slave station. Controls the operation of circuits, etc. The master station includes a master station phase control counter to control the phase control counter of each slave station, and operates in the same manner as the phase control counter circuit of the slave station.
The operation status of the slave station can be grasped by the count value, and the operation of each slave station in the transmission path is executed to realize the serial communication.

On the other hand, the master station recognizes a semi-infinite number of slave stations that can be connected to the transmission path with a fixed number of identifier information bits and performs one-to-one information exchange by performing a plurality of serial communication operations. Are configured to be executed separately.

One is communication for the purpose of recognizing a slave station existing on a transmission line, and is referred to as "initialization communication" in the following description. In this initialization communication, the identifier information of each slave station is downloaded, and the order of the slave stations in the transmission path is recognized. The other is communication in which a shift transfer data length is created and transferred in accordance with the slave station arrangement order recognized in the initialization communication, and is referred to as "normal communication" in the following description. In this normal communication, one-to-one information exchange is performed with each slave station. In other words, since the order of the slave stations connected to the current transmission path is unchanged after re-recognition by the initialization communication, the return information data length from each slave station according to the slave station order is shifted and returned. Therefore, information exchange can be easily realized.

Here, a basic idea for recognizing the number of slave stations which can be expressed by a fixed number of identifier information bits will be described. Note that, here, the description is made on the assumption that the fixed number of identifier information bits is 4 bits, but this is an assumption for easy understanding of the description, and is not particularly limited.

First, as a premise, slave stations are classified into two types based on the configuration of the equipment in which the serial communication device is used. On the other hand, a slave station used for a unit necessary for the operation of the device is called a main unit, and identifier information is assigned by a fixed value code. On the other hand, a slave station that is used for an option that is not necessarily required for the operation of the device and is a so-called extension unit is referred to as an option unit, and identifier information is assigned to each option unit as a code value of an assigned value. That is, the identifier information is all zero (0000B) and all one (111
1B) and fixed values for the main unit (here, (11
01B)) and 1 (0001B)
The code values are assigned to the option units in order from. In other words, considering the arrangement order of the transmission lines only by the main unit configuration, the arrangement order is an invariable arrangement order because of the required units. That is, since the set slave station arrangement for the main unit is invariable when the main unit is arranged alone, the memory map may be performed in accordance with the order of arrangement on the transmission path.

Next, a description will be given of a connectable optional unit slave station based on the main unit slave order. In the case of an optional unit slave station, it is unknown whether or not it is always connected to the transmission path, so the identifier information is assigned in order, especially when using a main unit whose arrangement order is determined in the main unit array. A plurality of option units existing between the main units are regarded as one group, and in the same group, unique identifier information is sequentially allocated to 1, 2, 3,... These groups are respectively configured between different main body units. That is, the identifier information to which the option unit is assigned may overlap between different groups.

According to the above concept, even if the number of slave stations is half-infinite, each slave station can be identified by 4-bit identifier information. In other words, up to thirteen optional units are allocated between the first and second main units with non-overlapping code values.

Thus, when there are five main units, for example, 4 × 13 = 52 optional units can be identified one-to-one. Conversely, if the number of optional units required for the main unit including the dummy is facilitated, a semi-infinite number of slave stations can be recognized as long as the electrical transmission capability of the transmission path is allowed.

The overall operation in the case where the serial communication device capable of connecting a semi-infinite number of slave stations described above actually executes communication will be described.

First, in a device in which a serial communication device is used as a master station, the total number of slave stations connectable to the serial communication transmission line and their arrangement order are set in advance. It is mapped to the memory for storage. Then, the master station performs serial communication by initialization communication, siphons identifier information according to the sequence of slave stations connected to the actual transmission path, and sets the presence / absence of slave stations registered in the memory. . This allows
The mapped slave station order is set to the slave station order existing in the current transmission path, and the memory map is reset. By this operation, the master station can grasp the arrangement order of the slave stations existing in the transmission path, and in the subsequent processing,
The data length of the shift transfer is constructed and output in accordance with the slave station order shown by the reset memory map, and the data length of the input shift transfer is stored in the memory in accordance with the slave station order shown by the reset memory map. And serial communication can be executed. The serial communication at this time is referred to as normal communication as described above,
Information is exchanged between the master station and each slave station.

As described above, in the execution of the normal communication which occupies most of the serial communication, the data of the number of information bits corresponding to the predetermined number of slave stations is prepared, and after the return data is loaded to each slave station, the shift operation is executed. Then, information can be transferred from the master station to each slave station or from each slave station to the master station, so that the communication time is minimized, signal processing is simplified, and the circuit configuration of the slave station is reduced. However, the cost is further reduced. On the other hand, in the normal communication, after making a round of the shift transfer for exchanging information, the second-order shift transfer is performed again with the same contents of information, and a single serial communication operation is performed. Is performed, and by comparing the first information content with the second information content, the accuracy of the information content can be improved with a simple configuration, and erroneous transmission of information can be prevented.

Hereinafter, the specific contents of serial communication by the conventional serial communication device will be described with reference to FIGS.

First, the operation of the conventional slave station will be described with reference to FIG. FIG. 6 is a block diagram showing a conventional slave station configuration.

In FIG. 1, reference numeral 1 denotes an input selector circuit. The input selector circuit 1 selects whether information returned from the slave station to the master station is identifier information which is parallel input information. 2 is an input latch circuit. The input latch circuit 2
It is connected to the output side of the input selector circuit 1 and latches the information selected by the input selector circuit 1 over the execution period of one serial communication. The output side of the input latch circuit 2 is connected to a first exclusive OR circuit (hereinafter, referred to as a "first EXOR circuit") 3 and a shift register circuit 4 for a slave station to execute shift transfer.

The first EXOR circuit 3 has an input latch circuit 2
, And the signal output from the input latch circuit 2 are input. The input and output of the input latch circuit 2 are compared bit by bit, and the comparison results are combined into one by a multi-input gate. The output is turned on when either the input to the input latch circuit 2 or the output from the input latch circuit changes even one bit.

The output side of the shift register circuit 4 is connected to a twice-read latch circuit 5 and a second exclusive OR circuit (hereinafter, referred to as a "second EXOR circuit") 6. The twice-read latch circuit 5 latches and holds the information of the first cycle of the shift transfer, and its output side is the second EX.
It is connected to an OR circuit 6 and an output latch circuit 7. The second EXOR circuit 6 compares the information content in the second shift transfer and the information content latched and held in the twice-read latch circuit 5 for each bit, and combines the comparison result into one signal by a multi-input gate. Output
Either the information content in the second shift transfer or the information content latched and held in the twice-read latch circuit 5 is 1
Turns on when a bit changes.

The output latch circuit 7 includes a second EXOR circuit 6
Only when all the bits match as a result of the comparison, the latch holding operation is executed, and the latched signal is output to the outside as a parallel output of the slave station.

The first decoding circuit 9 classifies and outputs a 2-bit slave station instruction coded signal designated by the master station into a soft reset signal, a forced reset signal, and a count instruction signal.

The gate circuit 8 is connected to the input selector circuit 1 and sends a selection instruction signal composed of a soft reset signal sent from the first decode circuit 9 and a transfer clock to the input selector circuit 1. Output, the input selector circuit 1 indicates the type of information to be selected.

The clock number counter circuit 10 is connected to the second decode circuit 12, counts the number of input transfer clocks, and outputs a timing pulse to the second decode circuit 12 for each predetermined value.

The phase control counter circuit 11 is connected to the first decode circuit, and uses the transfer clock as a count source to perform operations such as a count operation and a count stop hold in accordance with the count instruction signal classified by the first decode circuit 9. I do. Note that the master station also has master station phase control counter means operated in the same manner as the phase control counter circuit 11 and controls shift transfer.

The second decoding circuit 12 uses the Q output as the count result of the phase control counter circuit 11 as an input source, outputs an operation output instruction to each circuit based on the control phase timing, and outputs an input from each circuit. The signal is output to the main station as a return phase signal based on the control phase timing.

The operation of the shift register circuit 4 for executing the shift transfer is basically controlled by operating the count value of the phase control counter circuit 11 by the slave station coded signal instructed by the master station. You. Specifically, the count value of the phase control counter circuit 11 (hereinafter referred to as “control count value”) is controlled by timing control for executing a counter operation using a transfer clock as a clock source by a slave station coded signal generated by the master station. Operation control such as count-up, stop, and control count value reset is performed, and the second decode circuit 12 directly outputs a timing instruction signal to a circuit that executes each slave station operation.

Here, a flow of a conventional slave operation will be briefly described focusing on shift transfer.

When a soft reset is instructed by the slave station instruction coded signal, the control count value becomes "00H". During the soft reset, the input selector circuit 1 uses the fact that the control count value does not change even when the transfer clock is received.
Is selected. The gate circuit 8 is configured to switch the selection instruction signal of the input selector circuit 1 depending on whether a transfer clock is received during a soft reset. Thereby, in the input selector circuit 1, either one of the parallel input and the identifier input is selected,
The selected information is transmitted to the input latch circuit 2.

Thereafter, when the soft reset is released and a new transfer clock is received, the input information is latched and held in the input latch circuit 2, and the information is accessed to the shift-in parallel input of the shift register circuit 4. . On the other hand, the latch input and output of the input latch circuit 2 are the first E
The XOR circuit 3 compares the bits on a bit-by-bit basis.
Sent to This signal is a source of a communication request signal issued from the slave station, and is transmitted from the return phase signal to the master station at a predetermined control count value (here, it is assumed to be valid at the timing of 0EH). Is what is done.

When the master station subsequently instructs the control count value to be 01H, the output information of the input latch circuit 2 is shift-loaded into the shift register circuit 4, and the shift transfer operation is started upon receiving the transfer clock. From this time, the master station issues transfer data and a transfer clock of the number of pits corresponding to the number of slave stations in the transmission path grasped by initialization communication to be described later, and performs control count at a desired timing by a slave station instruction coded signal. While manipulating the value, instruction control is performed so that the control count value becomes 06H at the shift end timing at which the shift transfer is completed. When the control count value reaches 06H, the slave station determines that the first round of the shift operation has been completed, and reads the shift data of the shift register circuit 4 from the second decode circuit 12 to the twice-read latch circuit 5. A latch signal (latch pulse) is output to hold the latch. At this time, the information of the input latch circuit 2 latched and held at “00H” is accessible to the shift register circuit 4. Note that the information content latched and held in the input latch circuit 2 is not updated except when the control count value becomes "00H", so that the same information content is held when the control count value is 06H.

Then, the control counter value is set to "0" by the master station.
7H ", and the second round of the shift transfer is started. In the shift register circuit 4, the shift data is loaded again at "07H" and the shift operation is started. On the other hand, in the master station, the same information content as that in the first shift transfer is similarly loaded, and transfer data and a transfer clock having the number of bits corresponding to the number of slave stations in the transmission path are issued.

When the same operation as in the first cycle is performed and the control count value becomes "0CH" in accordance with the shift transfer end timing, it is determined that the second-order shift transfer has been completed, and the second EXOR circuit 6 In the above, the output of the twice-read latch circuit 5 holding the data of the first cycle and the output of the shift register circuit 4 having the second-order data are compared bit by bit. As a result, when all the contents match for each bit, the output of the second EXOR circuit 6 is turned off,
If any one bit does not match, the output is turned on.

When the control count value becomes "0DH", the second decode circuit 12 outputs a latch holding pulse to the output latch circuit 7 when the read results match twice. If the read results do not match, no latch holding pulse is output to the output latch circuit 7, and the return phase signal is turned on.

If the return phase signal is turned on when the control count value is "0DH", the master station determines that the shift transfer has failed due to a communication error and recognizes it as a communication error. In this case, as described later, the control count value is returned to “00H” by the soft reset, and the serial communication is executed again as a retry of the serial communication. In addition,
If an error occurs even after the retry communication is performed a predetermined number of times, the operation of the entire device is stopped as a serial communication failure, and the process is terminated in a state where a predetermined state such as a serviceman call is maintained. On the other hand, if the shift transfer is successful at “0DH”, the transfer information to the slave station is output as the slave station parallel output, and the shift transfer operation is terminated.

As a result, in the master station, the input shift transfer data from the slave station is read and compared twice, and when all the data match, the information content is updated to a predetermined memory. Also,
If the result of the double reading and comparison indicates that even one bit does not match, retry communication is executed after a soft reset.
If the master station determines that the shift transfer was successful,
The control count value is operated so as to be "0EH". This time, the state of the return phase signal is detected to determine the presence / absence of a slave communication request signal from each slave station. This "0E
The state of "H" is maintained until a communication request occurs in at least one slave station or master station. If there is a communication request, the control counter value is immediately set to "00H" and serial communication is performed again. Is executed.

That is, in the master station, the return phase signal at the time of “0DH” is used as a transfer error determination,
The return phase signal at the time of "EH" is used as a slave station communication request determination. As described above, the return phase signal output is configured to be read by the master station while distinguishing its meaning according to the control count value. Therefore, the master station is configured as necessary so that it can make determinations with various contents according to the control count value, and by devising the operation timing of the control count value, it is possible to categorize return signals indicating various meanings. it can.

On the other hand, in the slave station, when the control count value becomes "0EH", the second decoding circuit 12
The output state of the EXOR circuit 3 is output as a return phase signal. While the control count value is “0EH”, the presence / absence of a slave communication request is transmitted, and the latch information contents of the input latch circuit 2 in which the slave parallel input information shifted and transferred as described above is latched and held, As soon as even one bit of the contents of the slave station parallel input information currently accessed to the input terminal of the input latch circuit 2 is updated, it is output as a slave station communication request for requesting the master station to exchange information. With this signal, the same operation as the bidirectional serial communication configuration can be provided even in the case of the unidirectional serial communication configuration originally from the master station.

Next, a specific example of the conventional control of the main station will be briefly described with reference to FIGS.

FIG. 7 is a transmission path diagram when all slave stations that can be connected to the equipment using the conventional serial communication device are connected. The master station control is performed by the slave stations allocated in the order shown in FIG. The control is executed based on the arrangement order. Note that the slave station arrangement order of the basic transmission path is determined according to the equipment to be used.For example, if the slave station arrangement order is changed due to a specification change or the like, the basic station order is changed according to the content of the change. May be changed.

The transmission path diagrams of the serial communication apparatus shown in FIGS. 7 and 8 form a ring-shaped transmission path composed of the slave stations 22 to 33 starting from the master station 21.

FIG. 7 shows an arrangement order of all slave stations connectable to a transmission line, which is defined in advance in a serial communication device in a certain device. The slave station arrangement order is developed as a basic memory map set in the master station, and is mapped at the time of memory initialization setting processing operation of the whole CPU, which is executed at the time of resetting the CPU immediately after turning on the power. Is what is done. A memory map expansion shown in a memory map diagram (FIG. 8) described later indicates the order of arrangement of slave stations in a basic transmission line in the conventional example. In other words, the serial communication device maps the data on the basis of the sequence of the slave stations on the transmission line when all the slave stations determined in advance by the device are connected, and then executes the initialization communication to perform the memory map. Is reset. Then, when the normal communication is executed, the slave station arrangement order of the current transmission line is grasped, and the data length of only the information content constituted by the slave station arrangement order of the current transmission line is shifted and the information exchange is executed. You do it.

FIG. 8 is a transmission path diagram showing an example of the order in which slave stations are arranged in a transmission line in the serial communication apparatus at the time when a certain device actually operates. In the figure,
The order of the slave stations in the transmission path is different from the order of the slave stations in the basic transmission path (FIG. 7) by the electric units (switchback unit, high-voltage (blue) unit, high-voltage (yellow) in the example of FIG. ) Unit, envelope unit,
And five electric units of the double-sided control unit) are used in a state where they are omitted as necessary. The electric unit referred to as an option here is not limited to an option installed by a user, but also includes an option installed at the time of assembly in a factory, for example.

FIG. 9 is a conceptual diagram of a memory map used when the serial communication device performs information exchange.
The transition of the map figure of the storage memory which only the main station has is shown. In this figure, the slave-station parallel output information shown in FIG. 9A and the slave-station parallel input information shown in FIG. 9B are obtained by mapping the slave station arrangement order in the above-described basic transmission path. On the other hand, the slave station parallel output information shown in FIG. 9C and the slave station parallel input information shown in FIG. 9D map the slave station order on the current transmission line by initialization communication described later, and The map has been reset. That is, FIG. 9C and FIG.
By executing the normal communication based on the reset sequence of the slave stations shown in (d), information exchange with each slave station is performed, and the data content is updated. On the other hand, a device using such a conventional serial communication device executes device control by reading and writing the memory map. In FIG. 9, bits indicated by “X” and “Z” indicate information content updated with the execution of normal communication.

FIG. 10 is a flowchart showing a serial communication task when executing serial communication in a conventional serial communication device. FIG. 11 is a flowchart showing an initialization communication procedure when executing conventional serial communication. FIG. 12 and FIG. 13 are flowcharts showing a normal communication procedure when executing conventional serial communication. The initialization communication and the normal communication shown in FIGS.
It is started in the serial communication task shown in FIG. In the case of the normal communication, the shift transfer for executing the serial communication operation is performed twice, and the information contents of the first and second rounds are compared (that is, the above-described double transmission and double reading are performed). However, in the case of the initialization communication, the shift transfer for executing the serial communication operation is performed by one.
The communication operation is controlled to be forcibly terminated by performing a soft reset at the stage of the circulation. This is because the reset of the memory map is finished as soon as possible and the system can be shifted to the normal communication. With this process, the entire device can be started up as quickly as possible. Therefore, in the case of initialization communication, resetting of the memory map by shift transfer is rounded up in one round of shift transfer, and the processing shifts to the next normal communication as one serial communication.

In FIG. 10, the power is turned on and the CPU
By executing the initialization setting process of the memory of the CPU after the reset, the arrangement order of all the slave stations connectable to the basic transmission path is mapped to the memory part of the master station. The control program of the device is started, and at the same time, the serial communication task, which is the main station shown in FIG. 10, is also started.

Before executing the normal communication for exchanging information with each slave station, the master station first performs initialization communication for determining the order of arrangement of slave stations existing in the current transmission path. At this time, the memory status of the master station is as shown in FIGS.
This is the memory map shown in FIG.

When the serial communication task, which is the master station, is started, it is determined whether or not the retry counter value is equal to or greater than a predetermined value (step S101). Since the retry counter value is initially zero, it is next determined whether or not the memory map reset flag indicating “1” indicating that the memory map has been reset is “1” ( Step S102). If it is determined in step S102 that the memory map reset flag is “0”, the memory map is reset (step S103). Step S10
The memory map resetting of No. 3 is performed according to the flowchart shown in FIG.

That is, first, the communication software reset is turned on, and the idle transfer (one clock) of the transfer clock is performed in order to make the input selector circuit 1 of the slave station shown in FIG. 6 access the identifier information of the slave station (FIG. 6). Step S1
21). When the idle transfer of the transfer clock is not performed, the input selector circuit 1 of the slave station may be configured to access the information content of the slave station. Then, a memory pointer specified for resetting the memory map and a communication error flag for registering an error in the communication result are initialized to “00H” (step S1).
22) The memory pointer is incremented by "1" (step S123), and is indicated by a value obtained by adding the head value address (MTO) of the memory map of the slave station parallel output information in which the slave array order is registered in advance and the memory pointer value. It is determined whether or not the memory address to be read is equal to the final address (MTE) of the memory map of the slave parallel output information in which the slave array order is registered in advance (step S1).
24). If the two values are equal, it means that the scanning of the memory map has been completed.

If it is determined in step S124 that the value of the start value address MTO is not equal to the value of the end value address MTE, preparation for output of transfer data to be shifted is performed (step S125). In this initialization communication, all-zero transfer data is shift-transferred. However, the present invention is not particularly limited to this, and data having contents other than all-zero may be shift-transferred depending on the use of the serial communication device. .

Then, 4-bit shift transfer is executed in accordance with the configuration of the slave station circuit. That is, one-bit shift transfer is performed, the transfer clock is transferred by one clock, and the clock number counter is incremented by "1" (step S126), and one-bit shift transfer input is performed (step S127). It is determined whether or not the 4-bit shift transfer has been completed (step S12).
8).

By repeating the processing procedures of steps S126 to S128, shift transfer of 4 bits is executed. When the 4-bit shift transfer is completed in step S128, the identifier information from the first slave station returned to the master station by the shift transfer is processed.
Here, the contents of the memory address indicated by the sum of the start address MTO of the memory map, which is the slave parallel output information of the basic memory map, and the memory pointer value are picked up, and the contents of the upper 4 bits are picked up. It is acquired (step S129), and is compared with the 4-bit identifier information determined to be input completed in step S128, and it is determined whether or not both match (step S130).

If it is determined in step S130 that they match, it is determined that there is a slave station of the identifier information registered in the slave station parallel output information of the basic memory map, so that the above-described steps S123 to S130 are performed. Is executed again, and the presence or absence of the slave station is determined based on the identifier information by the next shift transfer.

If it is determined in step S130 that they do not match, it is determined that there is no slave station of the identifier information registered in the slave parallel output information of the basic memory map. The contents of the identifier information indicated by 4 bits are cleared to all zeros (00H), which means that there is no slave station, and re-registration is performed (step S).
131). Further, by incrementing the memory pointer by “1”, the slave station of the registered identifier information located next to the slave parallel output information of the basic memory map is designated (step S132), and the above-described step S1 is performed.
Returning to 29, the existence of the slave station is determined again.

That is, the registration is deleted by setting the contents of the memory area of the non-existing slave station to “00H”, and the existing slave memory area is left as it is by leaving the already registered identifier information as it is. The array order is reset.

When the above operation is repeated and the slave station arrangement order of the basic memory map is reset, step S12 is performed.
Since the value obtained by adding the value of the memory pointer to the value of the start value address MTO in the determination of 4 reaches the value of the end value address MTE, the total number of transfer clocks actually output in the shift transfer in execution of the initialization communication is counted. By dividing the value of the clock number counter of the master station by 4 bits, which is the number of bits forming one slave station, the total number of slave stations present on the current transmission path is calculated. This total number of slave stations and the reset memory map It is determined whether the total number of the slave stations determined to exist above matches (step S133).

If it is determined in step S133 that the calculated total number of slave stations coincides with the reset total number of slave stations on the memory map, the sequence of the slave stations is normally reset by the initialization communication. The flag is set to "1" and the communication software is reset (step S134).
The initialization communication is terminated. On the other hand, if they do not match, the reset has not been performed normally, so the retry counter is incremented by "1" and the communication software is reset while the reset flag remains "0" (step S13).
5) Once this procedure is completed.

Step S134 or step S135
When the initialization communication is completed by the
The serial communication task of 103 is temporarily ended.

Thereafter, the serial communication task is started again, and as described above, the retry counter value is less than the predetermined value and the step S102
If the memory map reset flag is “0” in the determination of, the initialization communication is retried again in step S103. If retry of initialization communication is repeated,
In step 135 of FIG. 11, the retry counter value reaches a predetermined value, and in step S101 of FIG. 10, it is determined that the value is equal to or larger than the predetermined value. In this case, it is determined that communication is not possible, and communication failure processing is executed (step S104).
This communication failure routine is to stop the operation of the entire device as a device failure, and is required to respond to a service person.

The above is the master station control of the initialization communication. Here, with reference to FIGS. 8 and 9 again, a specific initialization communication operation in the case of the conventional example will be briefly described from the operation of the entire serial communication device. The resetting of the memory map by the initialization serial communication is performed as shown in FIGS.
This is performed based on the basic memory map of the slave station arrangement order shown in (b). First, the master station initializes the slave station parallel output state by shifting and transferring the information content of the lower bit string of the slave station parallel output information of the memory map in the base station arrangement order to each slave station. In the case of the serial communication device of this conventional example, all zeros are set to initialize the slave station parallel output state, but the present invention is not particularly limited to this, and the contents of the initialization information are basic. This may be set in advance when the memory map in the slave station arrangement order is created. And in the main station, as described above,
A soft reset is issued to each slave station, and the input content of the slave station identifier is loaded into the shift register by operating the transfer clock. Thereafter, slave parallel output information for initializing the slave parallel output state is shifted and transferred. As a result, the slave station parallel output information contents to be initialized are output to the parallel output terminals to the slave stations, and the identifier information contents are sequentially returned to the master station in the slave station arrangement order of the transmission path. In the master station, this identifier information content is divided every 4 bits, compared with the order of the identifier information content registered in the memory map of the base slave array order, and the slave array order of the current transmission line is reset. You.

Here, the rules for the identifier information will be briefly described. The electric unit required for the device configuration is called a main unit, and a fixed value is assigned as identifier information. In addition, even if it is not a device configuration, an electrical unit that performs a device operation is called an option unit, and values are sequentially assigned as identifier information. However, in the case of an optional unit, it is not simply assigned in order from “1”. In other words, since the main unit always exists in the apparatus, it is only necessary to confirm that the main unit is located at the position of the transmission path set in advance, so that the identifier information can be set as a fixed value. On the other hand, since the option units always exist between the main units whose position order has already been determined, the numbers are sequentially assigned based on one main unit. Therefore, the identifier information of the option unit is identical between the main units and there is no duplicate identification information information, but it is allowed to be duplicated between the main units in different sets.
The identification determination is also possible. As shown in FIG.
The allocation of the identifier information is indicated by the upper 4 bits of the slave station parallel output information.

From the definition of the identifier information according to the above agreement,
The resetting of the memory map in the case of the transmission path shown in FIG. 8 will be described. Note that this memory setting is performed in the same manner as a general CPU memory operation, and is not limited to this format.

First, the identifier information (main unit) of the checker 33 is shifted and transferred to the master station. Here, since it is a main unit, the reference counter value is incremented to “01H”. On the other hand, the memory pointer counter value is not incremented and remains at "00H". Then, scanning is started from the start position address of the basic memory map, and the address position where the identifier information content of the main unit located in the order indicated by the reference counter value is registered is determined from the basic memory map. (Here, since it is "01H", the checker 33 which is the main body unit located first is calculated), and the reference pointer address is set at the address position. Then, the upper 4 bits of the memory at the address indicated by the memory pointer counter value and the addition result are compared with the contents of the identifier information shifted and transferred. Here, the 0th memory content “checker” of the main unit located at the 1st position is compared with the transferred content of the identifier information of the checker 33, and the two match. If they match, it is determined that there is a corresponding slave station, and the upper 4 bits set in the basic memory map are left as they are. This indicates that a slave station exists.

Next, the sorter identifier information (optional unit) is shifted and transferred. In this case, since this is an optional unit, the reference counter value is not incremented and remains at "01H", and the memory pointer counter value is set to "01H" which is incremented. As a result, the first memory (the "sorter" is shown in the figure) behind the first main unit.
Is compared with the transferred sorter identifier information content. As a result of the comparison, the two match and the corresponding slave is processed. Next, the identifier information to be shifted is shown in FIG.
Is the high-pressure red (optional unit) identifier, but is not the main unit, so the memory pointer counter value is incremented to “02H”. On the other hand, the reference counter value remains “01H”. Therefore, the memory located at the first position after the main unit located at the first position (denoted as "switchback" in the figure) is compared with the transferred sorter identifier information content. As a result, the two do not match, so the upper 4 bits of the switchback memory, which is the memory located second after the main unit located first, are reset to all zeros, thereby indicating that there is no corresponding slave station. It is.

Next, the value of the memory pointer counter is incremented again to "03H" and compared with the contents located in the next memory map. In this example, in this case also, it is determined that there is no match, and until the match, the memory of the mismatch is set without the corresponding slave station. When the memory pointer counter value is “04H”, that is, when the memory unit is compared with the memory located at the fourth position from the main unit located at the first position, both values match. Accordingly, this memory is set as having a slave station. Next, as can be seen from FIG.
(The main unit) is shifted and transferred. When the identifier information of the main unit is received, first, the option unit registered between the main units, starting from the memory after the value indicated by the reference counter value and the memory pointer counter value, and the reference counter value is indicated by the incremented value Are all set without the corresponding slave station. In this example, the high pressure (yellow) (optional unit) corresponds. Then, based on the incremented reference counter value, resetting of the basic memory map is continued.

When the reference counter is incremented, the memory pointer counter value is cleared to "0".
0H ". Then, the above-described operation is performed on all of the basic memory maps, whereby FIG.
The memory is reset as shown in FIG. In other words, this memory operation is basically performed from what position of the main unit to what position of the optional unit,
And the contents of the memory are set.

The above is the control operation of the initialization communication.

Next, a description will be given of normal communication controlled by the master station which performs information exchange with each slave station after the initialization communication.

In FIG. 10, when the initialization communication is performed in step S103, "1" is set in the memory map reset flag, and as a result, the memory map
As shown in the upper four bits of the slave parallel output information in (c), the slave array order in the basic memory map is reset to the slave array order of the slaves existing on the current transmission path.
Normal communication is performed based on the state of the slave station arrangement order.

If it is determined in step S102 in FIG. 10 that the memory map reset flag is "1",
It is determined whether or not the retry flag is "1" (step S105), and it is determined whether or not there is retry communication. In the retry communication, as in the case of the initialization communication, when one serial communication fails, the retry counter is incremented, and when the serial communication is within a predetermined value, the retry communication is executed. This retry communication means configuration has two types of communication means of the conventional serial communication device, that is, initialization communication and normal communication do not proceed simultaneously.
The same components are used. That is, when an error occurs in the retry communication exceeding a predetermined value, both the initialization communication and the normal communication are processed in the communication failure processing routine.

On the other hand, when the retry communication is executed, when the initialization communication is performed, as described above, step S in FIG.
At 135, the process of the retry counter is performed, and the retry communication is executed while the reset flag is reset, because it is not set in FIG. In the case of the normal communication, the process of the retry counter is performed in step S110 after the execution of the normal communication, and the execution of the retry communication is determined by the process of step S105. In other words, the retry communication control for the initialization communication and the normal communication is controlled separately, but the flags and counters necessary for the error processing routine and processing are shared.

Returning to FIG. 10, when the resetting of the memory map is completed, it is determined whether the retry communication is to be performed by checking whether the retry flag is "1" (step S105). . If no retry communication is determined in step S105, the master station communication request flag is set to “1”.
(Step S106) or whether the communication request signal at the slave station is on (step S107).
Is determined. When the master station communication request flag is set to "1" or when the slave station communication request signal is turned on, it indicates that execution of normal communication is requested. After the initialization communication is completed, the control count value of the slave station phase control counter circuit 11 and the control count value of the master station phase control counting means are both set to “00H” by the communication software reset. It is determined to be off.
Accordingly, the master station resets the master station communication request flag immediately after finishing the initialization communication, and instructs execution of the normal communication in step S106. On the other hand, if the normal communication is performed even once, the control count value is “0EH”,
As described above, the standby state is set to wait for the execution instruction of the normal communication. The process shifts from step S107 to step S110, where a processing signal such as a failure is reset, the task is temporarily ended as it is, and the processing after step S105 is performed again, thereby performing standby detection.
Then, when receiving the execution instruction of the normal communication, step S1
At 04, the normal communication shown in FIGS. 12 and 13 is executed.

In FIG. 12, first, a communication software reset is executed to synchronize the execution of communication (step S1).
41). Further, the communication abnormality flag, the memory pointer, the phase control counter, and the clock number counter are reset to “00H” (step S142). Then, the memory pointer for the memory operation is incremented (step S143), and the control counter value is loaded from the master station phase control counter (step S14).
4) It is determined whether or not the control counter value is a predetermined value (step S145). Here, “00” when the slave input information to be shifted and transferred from the slave is selected.
The determination is made based on the binary value of "06H" when the "H" shift transfer is performed once. Furthermore, the value of the result of the double reading comparison after performing the shift transfer twice is set to “0DH”, and is used for determination in steps described later. On the other hand, the validity period of the slave station communication request signal is set to “0EH”. Here, although the timing determination is not particularly performed, the communication operation in the normal communication is terminated, and the communication is ready for the next communication. Is controlled to be “0EH”.

If it is determined in step S145 that the control count value is the predetermined value, it is determined whether or not the return phase signal is ON (step S146). It is determined that the phase timings are normally synchronized, and step S15
0 processing is performed.

On the other hand, if it is determined in step S145 that the control count value is not the predetermined value, it is determined whether or not the return transport signal is turned off (step S147). If there is, it is determined that the phase timing is normally synchronized, and the process of step S150 is performed.

If it is determined in step S146 that the return phase signal is off at the time of on-check,
If the return phase signal is ON at the time of the OFF check in the determination of 147, it is determined that the phase timing is out of synchronization. Therefore, "1" is set to the phase error bit of the communication abnormality flag (step S148), the communication software reset is turned on (step S149), and the normal communication is canceled.

If it is determined in step S146 or S147 that the return phase signal is normal, normal communication is started. First, it is determined whether or not the sum of the memory pointer value and the start value address MTO of the reset memory map indicated by the slave station parallel output information is equal to the final value address MTE of the memory map (step S).
150).

If the two values are not equal, the shift transfer has not been completed yet, and the upper 4 bits of the memory contents indicated by the sum value address of the memory pointer value and the top value address MTO of the memory map are obtained. (Step S151), and it is determined whether or not the value is “00H” (step S152). Here, if it is “00H”, there is no slave station registered by resetting, so the flow returns to step S143 again, the memory pointer value is incremented, and shift transfer in the next slave station in the memory map is started.

In the determination of step S152, "00"
If it is not "H", the lower 4 bits of the memory content are obtained (step S153), and one-bit shift is performed for shift transfer (step S154). That is, in step S154, the content of one bit is shifted out, the transfer clock is output one clock, and the clock number counter is incremented by "1". Further, it is determined whether the value of the clock number counter means of the master station is a predetermined value (step S155). If the value is the predetermined value, the control count values of the phase control counters of the master station and the slave stations are respectively determined. "1" is incremented (step S156). On the other hand, if it is determined in step S155 that the value of the clock number counter is not the predetermined value, the process of step S156 is skipped. Then, a 1-bit return signal by the shift transfer is input (step S157), and it is determined whether or not the shift transfer for 4 bits corresponding to one slave station is completed (step S158).

If it is determined in this determination that the 4-bit shift transfer has not been completed, the process of step S154 is performed again. When the 4-bit shift transfer is completed, the 4-bit data is stored in the slave station parallel input information in the memory map shown in FIG. 9D (step S1).
59). Specifically, the shift-transferred 4-bit data is stored in the lower 4 bits of the memory content indicated by the sum value address of the memory pointer value and the start value address MTI of the memory map of the slave station parallel input information. , The information content is updated. Then, in order to repeat the abnormal operation to execute the shift transfer of the slave station, the process of step S143 is executed again. Then, as described above, if it is determined in step S150 that the data scan of the slave station to be shifted and transferred has completed one cycle, the processing after the execution of the normal communication is performed.

That is, the control counter value of the phase control counter is set to "0DH" (step S160),
It is determined whether the return phase signal is on (step S161). In this determination, if the return phase signal is ON, it means that an error has occurred in the double reading comparison in any of the slave stations, so the double reading comparison error bit of the communication abnormality flag is set ( Step S1
62), a communication software reset for executing the retry communication is executed (step S163), and the procedure is thereafter terminated.

On the other hand, if it is determined in step S161 that the return phase signal has not been turned on, it means that no error has occurred in the read comparison twice in all the slave stations. When the control count value is "0E
H ”(step S164), the communication request signal from each slave station is set to be valid, and the procedure ends.

Returning to FIG. 10, step S108 (FIG. 12)
When the normal communication process of FIG. 13) ends, it is determined whether or not the communication abnormality flag is “00H”, that is, whether or not the communication has ended normally (step S109). In this determination, when the communication abnormality flag is “00H”,
“0” is set to the retry flag and “00H” is set to the retry counter at step S11.
0), this task is terminated. Thereby, the communication standby state is continued until it is determined in step S106 or step S107 that there is a communication request from the master station or the slave station, and communication is basically not performed unless there is a request. .

If it is not "00H", some abnormality has occurred, so that the communication abnormality flag is analyzed (step S111), and "1" is set to the retry flag to instruct retry communication. And the retry counter is incremented (step S11).
2) This task is completed.

Although not shown, the communication abnormality flag is composed of a plurality of flags corresponding to various abnormal states. When the flag indicating that the content of the abnormal state is light is set by execution of the communication error flag analysis routine (here, the content of the abnormal state is set in advance into a light category and a severe category, and In step S112, the retry counter value is incremented by "1", and an instruction to execute retry communication is issued. On the other hand, when the flag indicating that the content of the abnormal state is heavy is set, the retry counter value is classified in advance so as to be directly set to a predetermined value causing an error on the spot.
When the task is started again after the task is terminated after the increment processing is performed, the retry communication is not executed, and the steps S101 to S104 are immediately performed.
Is performed, and the communication operation and the operation of the device are stopped in the communication failure processing routine.

The above is the master station control of the normal communication. This normal communication is executed after resetting the arrangement order of the slave stations existing on the current transmission line by performing the initialization communication, and when the arrangement order of the slave stations existing in the reset transmission changes. In this case, the initialization communication must be performed immediately to reset the memory.

Although not shown in the drawing, the part that generates the master station communication request includes a master station communication request flag that determines that each slave station needs to update information in each control task. set. Therefore, the master station checks the master station communication request flag in step S106 for controlling the normal communication of the serial communication task, and determines whether or not the normal communication is to be performed.

As described above, the normal communication is executed by sequentially shifting and transferring the lower 4-bit information contents validated by the slave station parallel output information of the reset memory map, and sequentially transmitting the returned information contents by the slave station parallel output. Only the lower 4 bits of the input information need be stored. In other words, once the memory is reset, the master station can exchange information with each slave station by simple and easy control such as simply transferring the contents of the memory.
In addition, the time required for executing the normal communication can be shifted by only the number of data bits for exchanging information, so that the processing can be performed in a minimum time.

However, whatever the device,
If the wiring between the electric units is disconnected or short-circuited for some reason, the operation of the device is not established. Not surprisingly,
The same applies to the serial communication device in the above conventional example. As a practical matter, when the apparatus becomes abnormal due to disconnection or short circuit, maintenance called a serviceman call is performed.

In recent years, equipment maintenance is mainly performed by finding an abnormal unit and exchanging the unit, thereby shortening the time required for the maintenance and minimizing the cost as much as possible.

[0093]

However, the above-described conventional serial communication device has the following problems.

That is, the conventional serial is configured as a unidirectional serial communication device led by the master station.
When the content of the slave station information is updated in any of the slave stations, a communication request signal is issued from the slave station to the master station, and the master station detecting this signal determines whether there is a master station communication request generated in the master station. Regardless, execute serial communication. As described above, the conventional serial communication is characterized in that information is exchanged in a bidirectional serial communication form in which the information content of the master station and the information content of each slave station are always exchanged in the latest state. There is.

That is, in the conventional serial communication device, the information exchange between the master station and the slave station is established only after a communication request from the slave station has occurred, and some abnormality has occurred in the communication request signal from the slave station. Therefore, if the communication request signal does not normally operate on the master station, serial communication itself will not be established.

The factors that prevent the communication request from the slave station from operating normally on the master station are as follows. (1) When the transmission path of the communication request signal transmitted from the slave station occurs, that is, when the transmission path of the communication request signal is When the communication becomes normal due to disconnection or short circuit, the communication request signal keeps on or off, and (2) temporarily turns on due to noise generated inside the equipment. In addition, there may be a case where the state is erroneously detected by the master station as a communication request signal. Since the disconnection / short-circuit of the above (1) does not change in chronological order, the disconnection / short-circuit of the transmission furnace may be detected using other means. However, since it is a probabilistic theory that it can occur when the phase timing between the noise and the main station coincides with each other, there is a problem that the abnormality cannot be detected accurately.

The present invention has been made in order to solve the above problems, and a serial communication apparatus, an abnormality diagnosis method, and a recording medium capable of easily and accurately performing an abnormality diagnosis due to erroneous transmission of noise or the like. The purpose is to provide.

[0098]

According to a first aspect of the present invention, there is provided a serial communication apparatus comprising a transmission line having a plurality of slave stations centered on a single master station, and a serial line transmitted from the master station. The master station shifts output information from the master station to the plurality of slave stations in synchronization with a transfer clock, and returns slave station information from the plurality of slave stations to the master station using the shift transfer. A serial communication device that performs serial communication for performing information exchange with the plurality of slave stations, wherein the plurality of slave stations each determine whether or not the content of the slave station information returned to the master station has been updated. Update determining means for determining, and a communication request signal transmitting means for transmitting a communication request signal to the master station when it is determined that the slave station information has been updated by the update determining means, the master station, When the content of the output information to be shifted and transferred to the plurality of slave stations is updated or when a communication request signal transmitted from any of the plurality of slave stations is received, the serial communication executing means for executing the serial communication is provided. In the serial communication device, the master station has output information storage means for storing contents of output information to be shifted and transferred to the plurality of slave stations, and input information storage for storing contents of slave station information returned from the plurality of slave stations. Means, wherein the input information storage means stores and holds the contents of slave information before execution of the serial communication, and the input information storage means stores and holds contents of slave information after execution of the serial communication. A second input information storage unit, and the contents of the slave information stored and held in the first input information storage unit after the execution of the serial communication; Means for comparing the contents of the slave station information stored and held in the means bit by bit, and the master station outputs the executed serial communication from the communication request signal transmitting means of the slave station. A comparison result judging unit for judging a comparison result by the comparing unit according to whether or not the execution is performed by the performed communication request signal; and performing the execution based on a result of the judgment by the comparison result judging unit. Self-diagnosis means for diagnosing whether information exchange by serial communication is not established.

In the serial communication apparatus according to a second aspect of the present invention, in the serial communication apparatus according to the first aspect, the self-diagnosis unit is configured to transmit the executed serial communication from the communication request signal transmitting unit of the slave station. If the comparison result determination unit determines that the comparison result by the comparison unit matches all the bits when the comparison is performed by the request signal, the information exchange by the executed serial communication is not established. Is configured to be diagnosed.

According to a third aspect of the present invention, in the serial communication apparatus according to the first aspect, the self-diagnosis unit is configured to transmit the executed serial communication from the communication request signal transmitting unit of the slave station. When the comparison result determination means determines that the comparison result by the comparison means matches all the bits when the execution is performed by the request signal, and when the executed serial communication is performed by the slave station, If the comparison result determination unit determines that at least one bit in the comparison result by the comparison unit does not match when the comparison result determination unit does not execute the communication request signal transmitted from the request signal transmission unit, It is characterized in that it is configured to diagnose that the information exchange by the performed serial communication is not established.

According to a fourth aspect of the present invention, in the serial communication apparatus according to any one of the first to third aspects, the information exchange by the serial communication is not established by the self-diagnosis means continuously for a predetermined number of times. A failure diagnosing means for diagnosing that a failure has occurred in the serial communication device when it is diagnosed.

According to a fifth aspect of the present invention, there is provided a method for diagnosing an abnormality in a serial communication apparatus, comprising a transmission line having a plurality of slave stations centered on one master station, wherein the master station synchronizes with a serial transfer clock generated by the master station. Performs information exchange between the master station and the plurality of slave stations by shifting and transferring the output information to the plurality of slave stations and returning the slave information from the plurality of slave stations to the master station using the shift transfer. A plurality of slave stations transmit a communication request signal to the master station when the content of the slave station information returned to the master station is updated. The master station performs the serial communication when the content of the output information to be shifted and transferred to the plurality of slave stations is updated or when a communication request signal transmitted from any of the plurality of slave stations is received. In the abnormality diagnosis method for a serial communication device configured to execute communication, in the master station, the content of slave station information before execution of the serial communication is stored and held in a first input information storage unit; The contents of the slave information after execution are stored and held in the second input information storage means, and the contents of the slave information stored and held in the first input information storage means and the second input information storage means after the execution of the serial communication. Is compared with the content of the slave information stored and held in each bit, and whether or not the executed serial communication is executed by the communication request signal output from the communication request signal transmitting means of the slave. And diagnosing whether or not the information exchange by the executed serial communication is not established based on the comparison result for each bit.

According to a sixth aspect of the present invention, in the abnormality diagnosis method for a serial communication device according to the fifth aspect, the self-diagnosis means transmits the executed serial communication from the slave station. When it is determined that the result of the comparison matches all the bits when the comparison is performed by the communication request signal, it is diagnosed that the information exchange by the performed serial communication is not established. And

According to a seventh aspect of the present invention, in the abnormality diagnosis method for a serial communication device according to the fifth aspect, the self-diagnosis means transmits the executed serial communication from the slave station. When it is determined that the result of the comparison matches all the bits when the communication is performed by the communication request signal, and when the performed serial communication is performed by the communication request signal transmitted from the slave station. If it is determined that at least one bit of the comparison result does not match when the information is not the same, it is diagnosed that the information exchange by the executed serial communication is not established.

The method of diagnosing abnormality of a serial communication device according to claim 8 is the method of diagnosing abnormality of serial communication device according to any one of claims 5 to 7, wherein the serial diagnosis is performed by the self-diagnosis means continuously for a predetermined number of times. When it is diagnosed that information exchange by communication is not established, it is diagnosed that a failure of the serial communication device has occurred.

The recording medium according to the ninth aspect is constituted by a transmission line having a plurality of slave stations centered on one master station, and from the master station to the plurality of slave stations in synchronization with a serial transfer clock generated by the master station. Serial communication for performing information exchange between the master station and the plurality of slave stations by shifting and transferring the output information of the plurality of slave stations and returning the slave station information from the plurality of slave stations to the master station using the shift transfer. A plurality of slave stations, each of the plurality of slave stations determines whether or not the content of the slave station information to be returned to the master station has been updated. Communication request signal transmission means for transmitting a communication request signal to the master station when it is determined that the information has been updated, wherein the master station updates the content of the output information to be shifted and transferred to the plurality of slave stations. An abnormality diagnosis program for a serial communication device comprising serial communication execution means for executing the serial communication when the communication request signal transmitted from any of the plurality of slave stations is received or when the communication request signal is received. An output information storing step of storing the content of output information to be shifted and transferred to the slave station; a first input information storing step of storing and holding the content of the slave station information before execution of the serial communication; and A second input information storage step of storing and holding the contents of the slave information; and after the execution of the serial communication, storing the contents of the slave information stored in the first input information storage means and the second input information storage means. A comparison step of comparing the content of the held slave station information bit by bit, and performing the executed serial communication with a communication request signal output from the slave station. A comparison result judging step of judging a result of the comparison in the comparing step according to whether or not the information has been executed, and information on the executed serial communication based on the judgment result in the comparison result judging step. An abnormality diagnosis program including a self-diagnosis step of diagnosing whether or not the replacement has failed is recorded in a computer-readable format.

A recording medium according to a tenth aspect is the recording medium according to the ninth aspect, wherein the executed serial communication is executed by a communication request signal transmitted from the slave station in the self-diagnosis step. When it is determined in the comparison result determination step that the result of the comparison in the comparison step matches all the bits, it is diagnosed that the information exchange by the executed serial communication is not established. I do.

According to an eleventh aspect of the present invention, in the recording medium according to the ninth aspect, in the self-diagnosis step, the executed serial communication is executed by a communication request signal transmitted from the slave station. When it is determined in the comparison result determination step that the result of the comparison in the comparison step matches all the bits, and the executed serial communication is executed by a communication request signal transmitted from the slave station. Diagnosing that the information exchange by the executed serial communication is unsuccessful when it is determined in the comparison result determination step that at least one bit of the result of the comparison by the comparing means does not match when not It is characterized by.

The recording medium according to claim 12 is the recording medium according to claim 9 or
12. The recording medium according to claim 11, wherein the abnormality diagnosis program is configured to execute the serial communication device when the information exchange by the serial communication is determined to be unsuccessful in the self-diagnosis step for a predetermined number of consecutive times. The method includes a failure diagnosis step of diagnosing that a failure has occurred.

[0110]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS.

Since the present embodiment can be realized by the configuration of the serial communication device described as the prior art, it will be described with reference to FIG. 6, but the serial communication device which can use the means intended by the present invention is described. If so, the configuration is not particularly limited to this.

Prior to the description of this embodiment, the CP of the main station
The program form of U will be described. This program form is configured in a task-type parallel processing form. In other words, each independent control program constitutes a plurality of tasks, a memory and port initialization settings and the like are executed by CPU reset after power-on, and a program called a monitor program to execute the start operation of each task is executed. It is done. Each task is processed in parallel and executed in real time. As a prior art, the serial communication task shown in FIG. 10 is also started by the monitor program, and once a predetermined processing operation is performed, the process is once returned to the monitor program, but when it is started again, the program is executed from the continuation of the previous time. Similarly, another task temporarily stops when a predetermined processing operation is performed, but is restarted to execute a subsequent control operation. As a result, the tasks are executed in parallel by sequentially executing predetermined processing operations, and the operation of the entire apparatus is controlled. Also, the cooperation between each task is
Control processing is performed by reading and writing the contents of the memory means of each task.

The program for executing the flowcharts shown in the following description is a task that is also processed in parallel, but for the sake of simplicity, the description will be made assuming that one continuous program process is performed. .

FIGS. 1 and 2 are flowcharts showing a serial communication task executed in the serial communication device according to the present embodiment.

When the serial communication task is started by the monitor program, first, it is determined whether or not the retry counter value is equal to or more than a predetermined value (step S1). Since the retry counter value is initially zero, it is next determined whether or not the memory map reset flag indicating “1” indicating that the memory map has been reset is “1” ( Step S2). If the memory map reset flag is "0" in the determination of step S102, the memory map in the order of the slave stations connected to the current communication transmission line is reset (so-called initialization communication) (step S102).
3) Then, this procedure is temporarily terminated.

Thereafter, the serial communication task is started again, and if the retry counter value is smaller than the predetermined value in the discrimination in step S1 and the memory map reset flag is "0" in the discrimination in step S2, step S3 is performed again. , Initialization communication is executed.

On the other hand, if it is determined in step S1 that the value of the retry counter is equal to or larger than the predetermined value, it is determined that communication is not possible, and communication failure processing is executed (step S1).
4). This communication failure routine is to stop the operation of the entire device as a device failure, and is required to respond to a service person.

If it is determined in step S2 that the memory map reset flag is "1", it is determined whether the retry flag is "1" (step S5).
The presence or absence of retry communication is determined. In the retry communication, as in the conventional case, when one serial communication fails, the retry counter is incremented, and when the serial communication is less than a predetermined value, the retry communication is executed.

If it is determined in step S5 that the retry flag is not "1", it is determined whether the slave station communication request signal is on (step S6) and whether the master station communication request flag is "1". (Step S7) is determined. In the conventional method, the communication request signal from the slave station is determined after determining the communication request flag generated inside the master station. However, in the present embodiment, the order is reversed, and the communication request signal from the slave station is determined. It is configured to determine a communication request generated inside the master station after the determination.

This is because when the serial communication is executed when there is a communication request from the slave station, the degree of change in the information content before and after the execution of the serial communication is determined, and the information content does not change despite the request for the slave station communication. This is to determine whether or not there is a contradiction in the communication execution result as in the case where the communication has been performed.
That is, unlike the conventional method, in which a communication request is issued to either the master station or the slave station, serial communication is executed and information exchange is executed. Therefore, it is important to distinguish whether the execution of serial communication is due to a communication request in the master station or a communication request signal from a slave station. Therefore, in this embodiment, when executing serial communication, It is necessary to confirm the presence or absence of a communication request signal from. The slave communication request signal described in the present embodiment is:
Since this is the same as that described as the conventional example, a detailed description thereof will be omitted.

If it is determined in step S6 that the communication request signal from the slave station has been turned off, and if it is determined in step S7 that the master station communication request flag has been reset to "0", the communication is started. Since there is no request, "0" is set in the retry flag and "00H" is set in the retry counter (step S8), and this task is terminated.

In step S6, it is determined that the communication request signal from the slave station has been turned off, and step S7
If it is determined that the communication request flag in the main station is "1", serial communication by normal communication is executed (step S9). Then, when the normal communication ends, it is determined whether or not the communication abnormality flag is “00H”, that is, whether or not the communication has ended normally (step S10).
If it is not "00H" in this determination, some abnormality has occurred, so that the communication abnormality flag is analyzed as in the conventional case (step S11), and the retry flag is issued to instruct retry communication. Is set to "1" and the retry counter is incremented (step S12), and this task is ended.

On the other hand, if it is determined in step S10 that the communication abnormality flag is "00H" and there is no abnormality in normal communication execution, it is determined whether the slave request flag is set (step S13). Here, since the communication request flag of the master station is determined to be "1", the slave station request flag is not set, and the answer in step S13 is negative (NO). Therefore, the process of step S8 described above is performed, and the present task ends.

Regardless of the presence or absence of a communication request in the master station, if the communication request signal from the slave station is on (step S6), the change in the information returned from the slave station before and after the execution of the serial communication is checked. Is set (step S14). Then, the content of the return information from the slave station stored and held by the previous serial communication execution is temporarily moved to another memory (step S15).

FIG. 3 is a memory map diagram of the master station. As shown in FIG. 3D, in the present embodiment, the upper 4 bits (“Z” in the figure) of the re-set slave parallel input information are reset.
n) is a memory area used for temporary movement. That is, as described in the conventional method, the content of the return information received from the slave station through the serial communication is the lower four bits of the memory map called the slave station parallel input information.
Stored in the bit part. When executing the slave station communication request self-diagnosis, the upper four bits of unused slave station parallel input information are used as an input information memory for temporary movement.

When the processing in step S15 ends, the processing in steps S9 and S10 described above is performed. If it is determined in step S10 that the communication abnormality flag is "00H" and there is no abnormality, the process proceeds to step S13.
At this point, if it is determined that there is a communication error,
Regardless of the validity / invalidity of the information exchange content by the serial communication, the retry communication is executed, and the slave station communication request self-diagnosis is not performed. In the determination in step S13, the slave request flag has been set in step S14. Accordingly, the slave request flag is reset (step S16), and
The contents of the upper 4-bit portion storing the return information from the slave station before the execution of the normal communication temporarily moved and the contents of the lower 4-bit portion updating the return information from the slave station after the execution of the normal communication are represented by bits. Each information is compared (step S17), and it is determined whether all information matches (step S1).
8).

In this determination, if at least one bit does not match, it is diagnosed that information exchange by normal communication has been established, so that the slave request abnormality counter is reset to "00H" (step S19), and the above-described step S8 is performed. After performing the processing of, this task is terminated.

In other words, since the information content from the slave station is updated, the normal communication is executed when a slave communication request is generated. If there is at least one update information content, the inconsistency occurs in the slave communication request. Because it is possible.
Therefore, if the comparison results of the information contents from the slave stations before and after the normal communication do not match, it is possible to diagnose that the communication request signal is obtained by updating the slave station information contents without contradiction.

On the other hand, as a result of the comparison of the information contents, if all match in the discrimination in step S18, there is an inconsistency in the communication request signal generated by the update of the slave station information content. And so on. Therefore, in this case, the information exchange by the normal communication is diagnosed as unsuccessful and is invalidated, and the slave station information set in the master station is returned to the previous state (step S1).
9). In other words, by transferring the upper 4 bits of the slave parallel input information, which is the temporarily shifted slave information contents, to the lower 4 bits of the slave parallel input information, the slave information is returned before the normal communication. .

Then, the slave request abnormality counter indicating that the slave communication request is abnormal due to contradiction is "1".
It is incremented (step S21), and it is determined whether or not the value of the slave request abnormality counter is equal to or greater than a predetermined value, thereby determining whether or not contradiction in the slave communication request has occurred continuously for a predetermined number of times. (Step S2
2). In this determination, if the slave request abnormality counter is smaller than the predetermined value, the process of step S8 is performed simply by invalidating the result of the current normal communication, and the task is terminated as it is.

If the value of the slave station communication abnormality counter is equal to or larger than the predetermined value, the value of the retry counter is set to step S.
(Step S)
23), the task is temporarily terminated. When the next serial communication task is started in this state, the communication failure processing routine is executed according to the determination in step S1, the subsequent serial communication is stopped, and processing such as a serviceman call is performed as a failure of the device (communication failure). Will be executed.

As described above, according to the present embodiment, when the serial communication result is inconsistent as in the case where the content of the slave station information is not updated despite the communication request from the slave station. , It is possible to accurately diagnose an abnormality due to erroneous transmission such as noise. Further, when the information exchange failure state continues for a predetermined number of times, the serial communication failure processing is executed, so that a runaway of the device due to erroneous transmission of the serial communication can be prevented.

In this embodiment, when the information exchange is not established, the contents of the slave station information held by the master station are returned to the state before the communication. However, the information exchange is not established. In the case of the slave station, the slave station parallel output state may be initialized once by software reset, and normal communication may be continued, and the master station information is accurately transmitted. The normal communication may be continued as it is.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS.

In the present embodiment, as in the first embodiment described above, the degree of change in the content of slave station information before and after normal communication is determined based on the presence or absence of a slave station communication request signal. Not only inconsistency that the content of the slave station information has not changed in spite of the normal communication performed by the communication request signal from the slave station. Even when it is determined that there is an inconsistency that the content of the slave station information has changed in spite of the normal communication executed only by the communication request in the station, the information exchange is determined to be unsuccessful. , Is different from the first embodiment.

FIGS. 4 and 5 are flowcharts showing a serial communication procedure executed in the serial communication device according to the present embodiment. In the figure, the same steps as those in the first embodiment shown in FIG. 3 are denoted by the same reference numerals. That is, in the serial communication task executed in the present embodiment, step S
The processes from 1 to S12 and from S14 to S15 are controlled in the same manner as in the first embodiment.

Therefore, if the normal communication according to the slave communication request is being executed, the slave request flag is set in step S14, and if the normal communication which is not due to the slave communication request is being executed, the slave request flag is set. However, the normal communication in step S54 is performed in this state.

If the communication abnormality flag is "00H" in the tail discrimination in step S10, unlike the first embodiment, the contents of the temporarily saved slave station information and the normal communication executed this time are obtained unconditionally. The contents of the slave station information are compared for all bits (step S31), and thereafter, it is determined whether or not the slave station request flag is set (step S32).

If it is determined in step S32 that the slave request flag is set, the slave request flag is reset (step S33), and it is determined whether or not all bits match as a result of the comparison in step S31. Is performed (step S34). In this determination, if all the bits match, there is a contradiction that the content of the slave station information has not been updated even though the normal communication has been executed according to the slave station communication request. Is returned to the state before the execution of the normal communication, thereby invalidating the current normal communication (step S35), and incrementing the slave request abnormality counter by "1". Then, it is determined whether or not the value of the slave request abnormality counter has become equal to a predetermined value (Step S).
37) If it is equal to the predetermined value, the value of the retry counter is set to a value larger than the predetermined value used in step S1 regardless of the current value (step S1).
38). This is because, as in the first embodiment described above, when the next serial communication task is started in this state, the communication failure processing routine is immediately executed according to the determination in step S1, and the subsequent serial communication is performed. Suspended,
This is to execute processing such as a serviceman call as a failure of the device (communication failure).

If it is determined in step S37 that the value of the slave request abnormality counter is smaller than the predetermined value, the result of the normal communication is simply invalidated in step S8.
Is performed, and this task is terminated as it is.

On the other hand, if it is determined in step S34 that the information of at least one bit does not match, the normal communication has been normally completed without any inconsistency, and "00H" is set in the slave request abnormality counter (step S34). S39) Then, the process of step S8 is performed.

If it is determined in step S32 that the slave request flag is not set, that is, if the normal communication is not performed according to the slave communication request, the process proceeds to step S32.
It is determined whether or not the result of the comparison of step 31 matches all bits (step S40). In this discrimination, if at least one bit of information does not match, there is a contradiction that the content of the slave station information has been updated in spite of execution of the normal communication without the slave station communication request. The processing after step S35 is executed. Further, step S
If all bits match in the determination at 40, the normal communication is not a slave communication request and the slave information content has not been updated and no inconsistency has occurred. Is done.

As described above, according to the present embodiment, not only the contradiction that the slave station information content does not change despite the normal communication executed by the communication request signal from the slave station, but also the slave station Even if it is determined that there is an inconsistency that the slave station information content has changed despite the normal communication being executed only by the communication request within the master station regardless of the communication request signal, the information exchange is also performed. It is determined that it is not established. Therefore, it is possible to easily and accurately diagnose an abnormality due to erroneous transmission such as noise while executing serial communication. Further, when the information exchange failure state continues for a predetermined number of times, the serial communication failure processing is executed, so that a runaway of the device due to erroneous transmission of the serial communication can be prevented.

(Other Embodiments) Even in a communication mode other than the serial communication shown in the first and second embodiments, communication is performed in response to a communication request from each slave station. It is needless to say that the same effect as in the first and second embodiments can be obtained if the communication mode is such a communication mode. In other words, it is determined whether or not inconsistency has occurred by checking the change in the content of the return information from the slave station before and after the execution of the communication each time the communication is executed in accordance with the presence or absence of the communication request from the slave station. Can be easily and accurately diagnosed while executing communication.

Further, according to the present invention, a storage medium storing a program code of software for realizing the functions of the above-described embodiments is supplied to a serial communication apparatus, and the CPU of the serial communication apparatus stores the program stored in the storage medium. It goes without saying that the object of the present invention is also achieved by reading and executing the code.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

Examples of a storage medium for supplying the program code include a floppy (registered trademark) disk,
Hard disk, optical disk, magneto-optical disk, CD-
A ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

The functions of the above-described embodiments are implemented when the computer executes the readout program code, and the OS or the like running on the computer is actually executed based on the instructions of the program code. It goes without saying that a part or all of the above processing is performed, and the function of the above-described embodiment is realized by the processing.

Further, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. Needless to say, a CPU or the like provided in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0150]

As described above, according to the abnormality detection method for the serial communication device according to any one of claims 1 to 3 or the serial communication device according to any one of claims 5 to 7, the master station uses the slave station before executing the serial communication. The contents of the information are stored and held in the first input information storage means, the contents of the slave information after the execution of the serial communication are stored and held in the second input information storage means, and the first input information storage is performed after the execution of the serial communication Comparing the contents of the slave information stored and held in the means with the contents of the slave information stored and held in the second input information storage means for each bit, and determining whether the serial communication has been executed by the slave. The information exchange by the executed serial communication is not successful based on the result of the bit-by-bit comparison depending on whether or not the communication is performed by the communication request signal output from the signal transmitting means. Since so as to diagnose whether or not an abnormality due to erroneous transmission of noise or the like, there is an advantage that it is possible to easily and accurately diagnose while performing the communication.

According to the method for diagnosing abnormality of the serial communication device of the fourth aspect or the serial communication device of the eighth aspect, the self-diagnosis means diagnoses that the information exchange by the serial communication is not established continuously for a predetermined number of times. In this case, since it is diagnosed that a failure has occurred in the serial communication device, it is possible to prevent the device device from running away due to the erroneous transmission of the serial communication.

According to the recording medium of the ninth to twelfth aspects, the recording medium is constituted by a transmission line having a plurality of slave stations centered on one master station, and the master station transmits the signals in synchronization with a serial transfer clock generated by the master station. Performs information exchange between the master station and the plurality of slave stations by shifting and transferring output information to a plurality of slave stations, and returning the slave station information from the plurality of slave stations to the master station using the shift transfer. A serial communication device for performing serial communication for the plurality of slave stations, wherein each of the plurality of slave stations determines whether or not the content of the slave station information to be returned to the master station has been updated; and the update determining means. Communication request signal transmitting means for transmitting a communication request signal to the master station when it is determined that the slave station information has been updated by the master station, wherein the master station outputs output information for shift transfer to the plurality of slave stations. When the content of is updated or when a communication request signal transmitted from any of the plurality of slave stations is received, the abnormality diagnosis program for the serial communication device includes serial communication execution means for executing the serial communication. An output information storing step of storing the contents of the output information to be shifted and transferred to the plurality of slave stations; a first input information storing step of storing and holding the contents of the slave information before executing the serial communication; A second input information storing step of storing and holding the contents of the slave information after the execution of the step (a), and after the execution of the serial communication, the contents of the slave information stored and held in the first input information storage means and the second
A comparison step of comparing the contents of slave station information stored and held in the input information storage means bit by bit, and whether or not the executed serial communication is executed by a communication request signal output from the slave station A comparison result determining step of determining the result of the comparison in the comparing step, and determining whether or not the information exchange by the executed serial communication is not established based on the result of the determination in the comparison result determining step. An abnormality diagnosis program including a self-diagnosis step of diagnosing is recorded in a computer-readable format, so that the computer of the conventional serial communication device reads and executes the abnormality detection program recorded on the recording medium. Thus, the same effect as that of the above-described serial communication device of claims 1 to 3 can be obtained.

According to the recording medium of the twelfth aspect, the abnormality diagnostic program is configured to execute the serial communication device when the information exchange by the serial communication is determined to be unsuccessful in the self-diagnosis step for a predetermined number of consecutive times. A failure diagnosis step of diagnosing that a failure has occurred, causing a computer of a conventional serial communication device to read and execute an abnormality detection program recorded on the recording medium, thereby making the above-described claim possible. 4 has the same effect as the serial communication device of No. 4.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a serial communication task executed in a serial communication device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a serial communication task executed in the serial communication device according to the embodiment.

FIG. 3 is a memory map diagram of a master station.

FIG. 4 is a flowchart illustrating a serial communication procedure executed in a serial communication device according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a serial communication procedure executed in the serial communication device according to the embodiment.

FIG. 6 is a block diagram showing a conventional slave station configuration.

FIG. 7 is a transmission path diagram when all slave stations that can be connected to a device using a conventional serial communication device are connected.

FIG. 8 is a transmission path diagram showing an example of the order of arrangement of slave stations in a current state of a transmission path in a serial communication device when a certain device actually operates.

FIG. 9 is a conceptual diagram of a memory map used when the serial communication device performs information exchange.

FIG. 10 is a flowchart showing a serial communication task when performing serial communication in a conventional serial communication device.

FIG. 11 is a flowchart showing an initialization communication procedure when performing conventional serial communication.

FIG. 12 is a flowchart showing a normal communication procedure when performing conventional serial communication.

FIG. 13 is a flowchart showing a normal communication procedure when performing conventional serial communication.

[Explanation of symbols]

 21 Master station 22-33 Slave station

Claims (12)

[Claims] 1. A transmission path having a plurality of slave stations centered on one master station, and shift-transferring output information from the master station to the plurality of slave stations in synchronization with a serial transfer clock generated by the master station. And a serial communication device that performs serial communication for executing information exchange between the master station and the plurality of slave stations by returning slave station information from the plurality of slave stations to the master station using the shift transfer. In addition, the plurality of slave stations each determine whether or not the content of the slave station information returned to the master station has been updated, and the update determining means determines that the slave station information has been updated. Communication request signal transmitting means for transmitting a communication request signal to the master station when the content of the output information to be shifted and transferred to the plurality of slave stations is updated, or A serial communication device including a serial communication execution unit that executes the serial communication when receiving a communication request signal transmitted from any of the slave stations, wherein the master station shift-transfers to the plurality of slave stations. Output information storage means for storing the content of the output information, and input information storage means for storing the content of the slave information returned from the plurality of slaves, the input information storage means, before the execution of the serial communication First input information storage means for storing and holding the content of slave station information, second input information storage means for storing and holding the content of slave station information after the execution of the serial communication, and the first input information storage means for executing the serial communication. Comparing means for comparing, on a bit-by-bit basis, the contents of the slave information stored and held in the storage means and the contents of the slave information stored and held in the second input information storing means; Further, the master station is configured to perform the comparison according to whether or not the executed serial communication is executed by a communication request signal output from the communication request signal transmitting unit of the slave station. And a self-diagnosis unit for diagnosing whether or not information exchange by the executed serial communication is not established based on a result of the determination by the comparison result determination unit. A serial communication device characterized by the above-mentioned. 2. The self-diagnosis means, when the executed serial communication is executed by a communication request signal sent from the communication request signal transmission means of the slave station, 2. The information processing apparatus according to claim 1, wherein when it is determined that the result of the comparison by the comparing means matches all the bits, it is determined that the information exchange by the executed serial communication is not established. A serial communication device as described. 3. The self-diagnosis means, when the executed serial communication is executed by a communication request signal sent from the communication request signal transmitting means of the slave station, When it is determined that the result of the comparison by the comparing means matches all the bits, and when the executed serial communication is not executed by the communication request signal transmitted from the communication request signal transmitting means of the slave station. When the comparison result determination unit determines that at least one bit of the comparison result by the comparison unit does not match, it is configured to diagnose that the information exchange by the executed serial communication is not established. 2. The serial communication device according to claim 1, wherein: 4. A failure diagnosis means for diagnosing that a failure has occurred in the serial communication device when the self-diagnosis means has diagnosed that information exchange by serial communication has not been established for a predetermined number of consecutive times. The serial communication device according to claim 1, wherein: 5. A transmission path having a plurality of slave stations centered on one master station, and shift-transferring output information from the master station to the plurality of slave stations in synchronization with a serial transfer clock generated by the master station. And a serial communication device that performs serial communication for executing information exchange between the master station and the plurality of slave stations by returning slave station information from the plurality of slave stations to the master station using the shift transfer. The plurality of slave stations are configured to transmit a communication request signal to the master station when the content of the slave station information to be returned to the master station is updated, and the master station is configured to transmit the plurality of slave stations. Serial communication configured to execute the serial communication when the content of the output information to be shifted and transferred is updated or when a communication request signal transmitted from any of the plurality of slave stations is received. In the apparatus abnormality diagnosis method, in the master station, contents of the slave station information before the execution of the serial communication are stored and held in a first input information storage means, and contents of the slave station information after the execution of the serial communication are input to a second input section. The contents of slave information stored and held in the first input information storage means and the contents of slave information stored and held in the second input information storage means after execution of the serial communication. Is compared for each bit, and the comparison result for each bit is determined depending on whether or not the executed serial communication is executed by a communication request signal output from the communication request signal transmitting unit of the slave station. A method for diagnosing whether or not the information exchange by the executed serial communication is unsuccessful on the basis of the above. 6. The self-diagnosis means, when the executed serial communication is executed by a communication request signal transmitted from the slave station, when the comparison result matches all bits. 6. The method for diagnosing abnormality of a serial communication device according to claim 5, wherein when it is determined that the information exchange by the executed serial communication is not established. 7. The self-diagnosis means determines that the comparison result matches all bits when the executed serial communication is executed by a communication request signal transmitted from the slave station. if you did this,
And when it is determined that at least one bit of the result of the comparison does not match when the executed serial communication is not executed by the communication request signal transmitted from the slave station, the executed 6. The method for diagnosing abnormalities in a serial communication device according to claim 5, wherein it is diagnosed that information exchange by serial communication is not established. 8. A method for diagnosing a failure of the serial communication device when the self-diagnosis unit diagnoses that the information exchange by serial communication is not established continuously for a predetermined number of times. Item 8. The abnormality diagnosis method for a serial communication device according to any one of Items 5 to 7. 9. A transmission line having a plurality of slave stations centered on one master station, and shift-transferring output information from the master station to the plurality of slave stations in synchronization with a serial transfer clock generated by the master station. And a serial communication device that performs serial communication for executing information exchange between the master station and the plurality of slave stations by returning slave station information from the plurality of slave stations to the master station using the shift transfer. In addition, the plurality of slave stations each determine whether or not the content of the slave station information returned to the master station has been updated, and the update determining means determines that the slave station information has been updated. Communication request signal transmitting means for transmitting a communication request signal to the master station when the content of the output information to be shifted and transferred to the plurality of slave stations is updated, or A serial communication execution means for executing the serial communication when receiving a communication request signal transmitted from any of a number of slave stations; An output information storing step of storing the content of the output information to be performed, a first input information storing step of storing and holding the content of the slave station information before executing the serial communication, and a content of the slave station information after executing the serial communication. A second input information storage step of storing and holding, and after execution of the serial communication, contents of slave information stored and held in the first input information storage means and slave stations stored and held in the second input information storage means A comparison step of comparing the content of information with each bit, and the executed serial communication is executed by a communication request signal output from the slave station. Whether the information exchange by the serial communication executed based on the result of the determination in the comparison result determining step and the result of the determination in the comparison result determining step is not established. A recording medium characterized by recording an abnormality diagnosis program including a self-diagnosis step of diagnosing the abnormality in a computer-readable format. 10. In the self-diagnosis step, when the executed serial communication is executed by a communication request signal transmitted from the slave station, a result of the comparison in the comparison step in the comparison result determination step 10. The recording medium according to claim 9, wherein when it is determined that all the bits match, the executed information exchange by serial communication is diagnosed as not being established. 11. In the self-diagnosis step, when the executed serial communication is executed by a communication request signal transmitted from the slave station, the result of the comparison in the comparison step is determined in the comparison result judging step. When it is determined that all the bits match, and when the executed serial communication is not executed by the communication request signal sent from the slave station, the comparison in the comparison means in the comparison result judging step is performed. 10. The recording medium according to claim 9, wherein when it is determined that at least one bit of the result does not match, it is diagnosed that the information exchange by the executed serial communication is not established. 12. The abnormality diagnosis program diagnoses that a failure of the serial communication device has occurred when it is determined that information exchange by serial communication is not established in the self-diagnosis step for a predetermined number of consecutive times. The recording medium according to any one of claims 9 to 11, further comprising a failure diagnosis step.