JP2000003312A - Synchronous serial communication system and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous serial communication system capable of early and correctly recognizing an abnormality of transmission/reception of communication data and improved in the reliability of a data communication, and to provide a control method therefor. SOLUTION: When a communication controller 409 transmits data to a slave communication IC 400, transmission data are transmitted to the slave communication IC 400 from a shift register 411 after they are transferred to a transmission buffer 412, and the transmission data are transferred to a buffer 403 of the slave communication IC 400. Next, the transmission data which perform reception operation and fetch them into the buffer 403 are received by a communication controller 409. The received data are transferred to a reception buffer 413 through a shift register 411. Data held in a transmission buffer 412 by a data comparison circuit 414 and data fetched in the reception buffer 413 are compared with each other and the comparison result is transmitted to a host CPU 420 by a comparison result information part 415.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous serial communication system, and more particularly, to a synchronous serial communication system for performing serial communication of control information data in an apparatus having a plurality of control units such as an image forming apparatus. And its control method.

[0002]

2. Description of the Related Art Conventionally, a serial communication system as shown in FIG. 1 has been known. 1, a communication controller 101 including a plurality of data registers, a selector, a serial communication control unit, a shift register, and the like, and a motor 10
Communication IC 102 to which a motor driver 105 for driving the IC 4 is connected and a communication IC 10 to which a plurality of sensors are connected
3 are cascade-connected via a total of four signal lines: a power supply line (+5 V), a ground line (GND), a synchronous clock signal line (CLK), and a data line (DATA).

FIG. 2 shows a configuration example in which such a serial communication system is applied to an image forming apparatus such as a copying machine. As shown in FIG. 2, this serial communication system includes a communication controller 201 and child communication ICs 2 connected to motor drivers 208 and 209 respectively driving motors 206 and 207 disposed at appropriate positions in the apparatus.
02 and 203, and the child communication IC 204 and the child communication IC 2 to which the plurality of sensor groups 210 and 211 are respectively connected.
05 is connected via one signal line. The communication controller 201 and the host CPU 210 are connected by a bus, and data communication is performed between the communication controller 201 and each of the communication ICs 202 to 205 under the control of the host CPU.
7 and read signals from the sensor groups 210 and 211.

[0004] Unique addresses, address 0, address 1, address 2, and address 3 are designated to each of the slave communication ICs 202 to 205 independently of the arrangement position in the apparatus.

When performing a transmission operation for transmitting predetermined phase data to drive the motor 206, the communication controller 2
01 sends a pulse train of a predetermined frequency to the synchronous clock signal line (CLK). In synchronization with the pulse train, the communication controller 201 and the slave communication IC 202
Processing is performed based on the transmission pulse train of the transmission data format of the data line (DATA) shown in (a). The communication controller 201 first sends out a start bit for notifying the start of communication, then a bit for designating transmission, an address bit string (A0 to A2) unique to the slave communication IC 202 of the communication partner, and a transmission data bit string (D0 to D7). ,
Parity bits (PA) are sequentially transmitted.

The slave communication IC 202 takes in the transmission data bit string and the parity bit only when the transmitted address bit string matches its own address. Next, the child communication IC 202 performs a parity error check from the transmission data and the parity bit, and as a result, an acknowledgment (ACK)
To the communication controller 201. If the ACK is normal, the communication controller 201 sends a stop bit to determine the transmission data, and terminates the transmission operation. The slave communication IC 202 supplies a drive control signal of the motor 206 to the motor driver 208 based on the transmission data. A
If CK is abnormal, the communication controller 201 terminates the transmission operation without sending a stop bit. Therefore,
The drive control signal for the motor 206 is not supplied to the motor driver 208.

Next, the receiving operation when the communication controller 201 receives the output signal of the sensor group 210 from the slave communication IC 204 will be described. When performing the receiving operation, the communication controller 201 transmits the synchronous clock signal line (CL
K), a pulse train of a predetermined frequency is transmitted. The communication controller 201 and the communication IC 204 perform processing based on the reception pulse train of the reception data format of the data line (DATA) shown in FIG. 3B in synchronization with the pulse train. The communication controller 201 first sends out a start bit for notifying the start of communication, and then sends out a bit for designating reception and an address bit string (A0 to A2) of the slave communication IC 204 as a communication partner in order. The slave communication IC 204 sends out transmission data and a parity bit (PA) only when the address bit string matches its own address, and the communication controller 201 performs a parity check from the received data and the parity bit, and if the result is normal. If so, the received data is determined and the transmission operation is terminated.

[0008] By using the serial communication system having such a configuration, it is possible to control the operation of a plurality of motors and sensors arranged in various parts of the apparatus and read information by using cascade-connected signal lines.

[0009]

However, in the above-mentioned conventional serial communication system, error detection of communication data relies only on parity error check, and only the parity error check function is used in an environment where the system is installed. In some cases, it is not possible to accurately confirm whether communication data has been transmitted and received normally, and reliability is lacking.

[0010] The present invention solves the problems of the conventional serial communication system, and can promptly and accurately recognize abnormalities in transmission / reception of communication data and transmission of abnormal data, thereby improving the reliability of data communication. An object of the present invention is to provide an improved synchronous serial communication system and a control method thereof.

[0011]

According to the first aspect of the present invention, there is provided a communication control means for controlling communication, and the communication control means being connected to the communication control means via a communication line. In a synchronous serial communication system including a slave communication unit that transmits and receives data to and from a control unit, the communication control unit includes a first storage unit that holds transmission data, and a reception unit that receives transmission data from the slave communication unit. A second storage unit for storing data; and a comparison unit for comparing data in the first storage unit with data in the second storage unit, wherein the child communication unit is And a drive unit for outputting the data of the third storage unit, wherein the communication control unit performs a transmission operation and a reception operation with respect to the child communication unit. Continuously There, compares the data of the data and the second storage means of the first storage unit by the comparison means, and outputs the comparison result.

In order to achieve the above object, a control method of a communication system according to a first aspect of the present invention includes a communication control means connected to a CPU for controlling communication, and a communication control means connected to the communication control means via a communication line. A slave communication means for transmitting and receiving data to and from the communication control means and outputting the received data as control information, wherein the communication control means stores the transmission data in a first storage means. Holding the transmission data to child communication means for designating the transmission data, and the communication means storing the transmission data in a second storage means;
Outputting the data of the storage means as control information; receiving the data stored in the second storage means by the communication control means and storing the data in the third storage means; And the step of comparing the data of the third storage means with the data of the third storage means, and outputting the result of the comparison to the CPU.

Preferably, in the invention described in claim 2, in claim 1, the communication control means includes a communication control means for transmitting and receiving data in the first storage means and data in the second storage means, respectively. One shift register,
The child communication means has a second shift register for transmitting and receiving data of the third storage means.

Preferably, in the third aspect of the present invention, in the first aspect, a plurality of the child communication means are connected to the communication line, and the communication control means communicates with the designated child communication means. It is characterized by the following.

More preferably, in the invention according to claim 4, in claim 1, the slave communication means generates a latch signal after transmission of data from the communication control means and sends it to the drive means. A latch signal generating unit, wherein the drive unit outputs data of the third storage unit according to the latch signal.

In order to achieve the above object, according to the invention as set forth in claim 5, communication control means for controlling communication, and communication control means connected to the communication control means via a communication line between the communication control means. In a control method of a synchronous serial communication system including child communication means for transmitting and receiving data,
A holding step of holding transmission data from the communication control means in a first storage means of the communication control means; a transmission step of transmitting the transmission data to the communication means; Storing the data in the third storage means, outputting the data in the third storage means, and receiving the data stored in the third storage means from the slave communication means to the communication control means. Receiving the received data from the slave communication means, storing the received data from the slave communication means in the second storage means of the communication control means, and storing the data in the first storage means and the second storage in the communication control means. A comparing step of comparing with the data of the means, and a comparison result output step of outputting the comparison result, wherein the transmitting step and the receiving step are continuously performed. On the line, it performs the comparing step, and outputs the comparison result.

According to a sixth aspect of the present invention, there is provided a communication control means for controlling communication between the communication control means and the communication control means connected to the communication control means via a communication line. In a synchronous serial communication system including a child communication unit that transmits and receives data, the communication control unit includes a first storage unit that holds transmission data, and a second storage unit that stores reception data from the child communication unit. Storage means, comparison means for comparing the data in the first storage means with the data in the second storage means, and a latch signal generating means for generating a latch signal when the comparison results by the comparison means match Means, wherein the child communication means comprises: third storage means for holding data received from the communication control means;
A drive unit for outputting data of the third storage unit, wherein the communication control unit continuously performs a transmission operation and a reception operation with respect to the child communication unit, Comparing the data in the storage means with the data in the second storage means, outputting the comparison result, and sending the latch signal to the drive means by the latch signal generation means when the comparison result matches. And outputting the data of the third storage means.

Preferably, in the invention described in claim 7, in claim 6, the communication control means includes a communication control means for transmitting and receiving data in the first storage means and data in the second storage means, respectively. One shift register,
The child communication means has a second shift register for transmitting and receiving data in the third storage means.

Preferably, in the invention according to claim 8, in claim 6, a plurality of the child communication means are connected to the communication line, and the communication control means communicates with the designated child communication means. It is characterized by the following.

Preferably, in the invention of claim 9, in claim 6, the latch signal generating means and the drive means are connected by a signal line.

In order to achieve the above object, according to the invention of claim 10, communication control means for controlling communication, and communication control means connected to the communication control means via a communication line between the communication control means and the communication control means. In a control method of a synchronous serial communication system including communication means for transmitting and receiving data,
Holding the transmission data from the communication control means in the first storage means of the communication control means; transmitting the transmission data to the child communication means; Storing the data in the third storage means, outputting the data in the third storage means, and receiving the data stored in the third storage means from the slave communication means to the communication control means. Receiving the received data from the slave communication means, storing the received data from the slave communication means in the second storage means of the communication control means, and storing the data in the first storage means and the second storage in the communication control means. A comparing step of comparing with the data of the means, and a latch signal generating step of generating a latch signal when the comparison result matches, the transmitting step; The receiving step is performed continuously, the comparing step is performed, the comparison result is output, and when the comparison result matches, the latch signal is generated by the latch signal generating step, and the data signal is output. In the output step, the data of the third storage means is output.

To achieve the above object, according to the eleventh aspect of the present invention, there is provided a communication control means for controlling communication, and a communication control means connected to the communication control means via a communication line. In a synchronous serial communication system including child communication means for transmitting and receiving data, the communication control means includes: first storage means for holding transmission data;
Second storage means for storing data received from the child communication means, comparison means for comparing data in the first storage means with data in the second storage means, and a comparison result by the comparison means A first latch signal generating unit that generates a latch signal when the two match, wherein the slave communication unit includes a third storage unit that holds data received from the communication control unit; and a third storage unit. Drive means for outputting a latch signal, a second latch signal generation means for generating a latch signal after transmission of data from the communication control means and sending the latch signal to the drive means, and a latch for inputting a latch signal from outside Signal input means, and latch signal selection means for selecting a latch signal from the second latch signal generation means or a latch signal from the latch signal input means. That.

Preferably, in the invention according to claim 12,
12. The communication control unit according to claim 11, wherein the communication control unit includes a first shift register for transmitting and receiving the data of the first storage unit and the data of the second storage unit, respectively, It has a second shift register for transmitting and receiving the data of the third storage means.

Preferably, in the invention according to claim 13,
12. The communication system according to claim 11, wherein the plurality of child communication units are connected to the communication line, and the communication control unit communicates with the specified child communication unit.

Preferably, in the invention according to claim 14,
12. The communication control unit according to claim 11, wherein the comparison unit compares the data in the first storage unit with the data in the second storage unit by the comparison unit, and outputs a result of the comparison. .

Preferably, in the invention according to claim 15,
12. The comparison unit according to claim 11, wherein the first latch signal generation unit and the latch signal input unit are connected by a signal line, and when the latch signal from the latch signal input unit is selected by the latch selection unit. A latch signal is sent from the first latch signal generating means to the drive means when the result of comparison by
The data of the storage means is output.

Preferably, in the invention according to claim 16,
12. The device according to claim 11, wherein when the latch signal from the second latch signal generating means is selected by the latch selecting means, the latch signal is generated by the second latch signal generating means after data transmission from the communication control means is completed. Is generated and transmitted to the drive unit, and the drive unit outputs data of the third storage unit in accordance with the latch signal.

Preferably, in the invention according to claim 17,
12. The communication control unit according to claim 11, wherein the communication control unit continuously performs a transmission operation and a reception operation with respect to the child communication unit, and the comparison unit stores the data in the first storage unit and the second storage unit.
Is compared with the data in the storage means, and the comparison result is output.

Preferably, in the invention according to claim 18,
12. The communication control unit according to claim 11, wherein the communication control unit includes an operation selection unit that selects an operation of continuously performing a transmission operation and a reception operation with respect to the child communication unit, and performs the transmission operation and the reception operation continuously. When the operation is not selected, the operation of the comparing means is prohibited.

In order to achieve the above object, according to the invention of claim 19, communication control means for controlling communication, and data communication between the communication control means connected to the communication control means via a communication line. In the control method of the synchronous serial communication system including a child communication unit that performs transmission and reception of,
A holding step of holding transmission data from the communication control means in a first storage means of the communication control means; a transmission step of transmitting the transmission data to the child communication means; A storing step of storing data in the third storage means, a data output step of outputting data of the third storage means, and a step of transferring the data stored in the third storage means from the slave communication means to the communication control means. A receiving step of receiving, a storing step of storing received data from the child communication means in a second storage means of the communication control means, and a step of storing the data of the first storage means and the second A comparing step of comparing with data in the storage means, a first latch signal generating step of generating a latch signal when the comparison result matches,
A second latch signal generating step of generating a latch signal after the transmission of data from the communication control means and outputting the data of the third storage means, a latch signal inputting step of externally inputting a latch signal, And a latch signal selection step of selecting a latch signal generated by the second latch signal generation step or a latch signal input to the latch signal input step.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 4 is a diagram showing a main configuration of the synchronous serial communication system according to the first embodiment of the present invention. In the figure, a child communication IC 400 which is a child communication means to which a driving means such as a motor is connected,
Control unit 401, shift register 402, buffer 40
3, an output driver 404, a reset circuit 405, and a latch signal generation circuit 406. A communication controller 409, which is a communication control unit, includes a control unit 410, a shift register 411, a transmission buffer 412, a reception buffer 413, a data comparison circuit 414, a comparison result notification unit 415, and a plurality of data registers (data registers 0 to 7). A data register 416 is provided. The communication controller 409 is connected to the host CPU 420 via a bus. The communication controller 409 and the plurality of slave communication ICs 400 (only one is shown in the figure) are cascaded by the above-described signal lines.

Next, the operation of the above configuration will be described.
Communication controller 40 for controlling the operation of the motor and the like
When the host CPU 420 transmits data from the communication controller 409 to the child communication IC 400, the host CPU 420
The transmission data is written into one of the data registers 416 corresponding to C400. The communication control unit 410 transmits the transmission data of the data register 416 to the child communication IC 4 in the following procedure based on a predetermined communication protocol.
Send to 00.

The transmission data held in the data register 416 is transferred to the transmission buffer 412 and then to the shift register 411. The transmission data (SDATA) transferred to the shift register 411 is transmitted to the slave communication IC 400 in a data format as shown in FIG. 3A in synchronization with the synchronization clock pulse (SCLK) of the synchronization clock signal line (CLK). .

Under the control of the control unit 401, when the transmitted address bit string matches its own address under the control of the control unit 401, the slave communication IC 400 takes in the transmission data into the shift register 402 and checks the transmission data by parity error check. Is normal, buffer 40
Transfer to 3. When the stop bit transmitted from the communication controller 409 is received, the latch signal generation circuit 40
6 generates a latch signal, and the output driver 404 latches the data in the buffer 403 to control information (DO).
(UT) to the motor.

When the transmission operation is completed, the communication controller 409 performs a reception operation on the slave communication IC 400 that has transmitted the data based on a predetermined communication protocol. When the slave communication IC 400 receives the reception bit transmitted by the communication controller 409 and the address bit string corresponding to its own address, the slave communication IC 400 transfers the transmission data (SDATA) fetched into the buffer 403 to the shift register 402 and transmits the synchronization clock pulse (SCLK). SCLK) and transmits it to the communication controller 409. The transmitted data is taken into the shift register 411 of the communication controller 409 by a series of receiving operations, and is transferred from the shift register 411 to the receiving buffer 413 if the received data is normal by the parity error check.

When the receiving operation is completed, the data comparing circuit 4
14, the data held in the transmission buffer 412 is compared with the data taken in the reception buffer 413,
The comparison result is sent to the host CPU 4 by the comparison result notification unit 415.
20.

The notification means of the comparison result notification unit 415 may be a flag operation by a register or a signal output for an interrupt signal.

According to the present embodiment, the transmission buffer 41
2 does not match the data in the reception buffer 413 received from the slave communication IC 400, that is, the transmission data transmitted by the communication controller 409 and the slave communication IC
If the data received by 400 does not match, host C
Since the PU 420 can recognize the abnormality of the transmission data based on the signal from the comparison result notifying unit 415, it is possible to take recovery measures such as stopping the motor and transmitting the data again within a short time.

FIG. 5 is a diagram showing a main configuration of a synchronous serial communication system according to a second embodiment of the present invention. In the figure, a child communication IC 500 as a child communication unit to which a driving unit such as a motor is connected includes a control unit 501, a shift register 502, a buffer 503, and an output driver 50.
4. A reset circuit 505 is provided. A communication controller 509 serving as a communication control unit includes a control unit 510, a shift register 511, a transmission buffer 512, and a reception buffer 51.
3, a data comparison circuit 514, a comparison result notification unit 515, a data register 516 including a plurality of data registers (data registers 0 to 7), and a latch signal generation circuit 517. The communication controller 509 is connected to the host CPU 520 via a bus. The communication controller 509 and a plurality of slave communication ICs 500 (only one is shown in the figure) are cascaded by the signal lines described above.

Next, the operation of the above configuration will be described.
Communication controller 50 for controlling the operation of the motor and the like.
When the host CPU 520 transmits data to the child communication IC 500 from the
The transmission data is written into one of the data registers 516 corresponding to C500. The communication control unit 510 transmits the transmission data of the data register 516 to the child communication IC 5 according to the following procedure based on a predetermined child communication protocol.
Send to 00.

The transmission data held in the data register 516 is transferred to the transmission buffer 512 and then to the shift register 511. The transmission data (SDATA) transferred to the shift register 511 has a data format as shown in FIG.
K) is transmitted to the slave communication IC 500 in synchronization with the synchronous clock pulse (SCLK).

Under the control of the control unit 501, when the transmitted address bit string matches its own address under the control of the control unit 501, the slave communication IC 500 takes in the transmission data into the shift register 502 and transmits it by parity error check. If the data is normal, the data is transferred to the buffer 503.

When the above-described transmission operation is completed, the communication controller 509 performs a reception operation on the slave communication IC 500 that has transmitted the data based on a predetermined communication protocol. When the slave communication IC 500 receives the reception bit transmitted by the communication controller 509 and an address bit string matching its own address, the slave communication IC 500 transfers the data fetched by the buffer 503 to the shift register 502, and outputs a synchronous clock pulse (SCLK) Is transmitted to the communication controller 509 in synchronization with. The data received by the communication controller 509 is taken into the shift register 511 by a series of receiving operations. If the data is normal by the parity check, the data is transferred from the shift register 511 to the reception buffer 513.

When the receiving operation is completed, the data comparing circuit 5
14, the transmission data held in the transmission buffer 512 is compared with the data transferred to the reception buffer 513, and the comparison result is notified by the comparison result notifying unit 515 to the host CP.
Sent to U520. At the same time, if the comparison results match, a latch signal is generated by the latch signal generation circuit 517, and the latch signal is transmitted via the signal line to the child communication IC 50.
0 is sent to the output driver 504. Output driver 5
Reference numeral 04 latches transmission data in the buffer 503 and outputs data (DOUT) to the motor. If the comparison results do not match, no latch signal is sent from the latch signal generation circuit 517, and no data is output from the output driver 504 of the slave communication IC 500.

Host CPU 52 of comparison result notifying section 515
The means for notifying to 0 may be a flag operation by a register or a signal output for an interrupt signal.

According to the present embodiment, the host CPU 52
0 can recognize the abnormality of the transmission data by the signal from the comparison result notifying unit 515, so that it is possible to take a recovery action within a short time. In addition, the transmission data transmitted by the communication controller 509 and the child communication IC 500 If the received data does not match, no data is output from the output driver 504 of the child communication IC 500, so that output of abnormal control information is prohibited, and illegal operation of the motor and the like can be prevented.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram showing a main configuration of a synchronous serial communication system according to a third embodiment of the present invention. In the figure, a slave communication IC 600 to which driving means such as a motor is connected includes a control unit 601, a shift register 602, a buffer 603, an output driver 604,
The circuit includes a reset circuit 605, a latch signal generation circuit 606, and a latch signal selection circuit 607. Communication controller 60
9 denotes a control unit 610, a shift register 611, a transmission buffer 612, a reception buffer 613, a data comparison circuit 61
4, a data register 616 including a plurality of data registers (data registers 0 to 7), a comparison result notifying unit 615,
A latch signal generation circuit 617 and a transmission / reception selection circuit 618 are provided. The communication controller 609 is connected to the host CPU 620 via a bus. The communication controller 609 and the plurality of child communication ICs 600 (only one is shown in the figure) are cascaded by the signal lines described above.

Next, the operation of the above configuration will be described.
In this embodiment, the transmission / reception selection circuit 618 determines whether or not to select communication control for continuously performing the transmission operation and the reception operation of the communication controller 609 by the host CPU.
620 can be determined. If the continuous control of the transmission / reception operation is not selected, the data comparison circuit 6
The data comparison function of No. 14 is not used, and only the transmission operation is performed similarly to the conventional control method, and it is determined whether the transmission data is normal only by the parity error check. When the continuous control of the transmission / reception operation is selected, that is, the data comparison circuit 6
If the user selects to use the fourteenth function, the latch signal selection circuit 607 further uses the latch signal generation circuit 606 in the child communication IC 600 or the latch signal generation circuit 617 in the communication controller 609. Can be selected.

When the use of the latch signal generation circuit 617 is selected, the following operation is performed. In order to drive a motor or the like, data is transmitted from the communication controller 609 to the child communication IC 600.
, The host CPU 620 writes the transmission data to one of the data registers 616 corresponding to the child communication IC 600 in the communication controller 609, and the communication control unit 610 performs the following procedure based on a predetermined communication protocol. To send the transmission data to the child communication IC 60
Send to 0.

The transmission data held in the data register 616 is transferred to the transmission buffer 612 and then to the shift register 611. The transmission data transferred to the shift register 611 has a data format as shown in FIG. 3A and is synchronized with the synchronous clock pulse (SCLK) of the synchronous clock signal line (CLK) to the slave communication IC 60.
Sent to 0.

Under the control of the control unit 601, the slave communication IC 600 captures transmission data into the shift register 602 when the transmitted address bit string matches its own address based on the communication protocol, and checks the transmission data by parity check. If normal, the data is transferred to the buffer 603. When the above transmission operation is completed, the communication controller 609 performs a reception operation based on a predetermined communication protocol. In response to a reception command including a reception bit and an address bit string transmitted from the communication controller 609, the slave communication IC 600 transfers the transmission data fetched into the buffer 603 to the shift register 602, and sends the transmission data to the communication controller 609 in synchronization with a synchronous clock pulse (SCLK). Send. The transmission data received by the communication controller 609 is taken into the shift register 611 by a series of reception operations, and is transferred from the shift register 611 to the reception buffer 613 if the received data is normal by the parity check.

When the receiving operation is completed, the data comparing circuit 6
14, the transmission data held in the transmission buffer 612 is compared with the reception data transferred to the reception buffer 613, and the comparison result is notified by the comparison result notifying unit 615 to the host C.
Sent to PU 620. At the same time, if the comparison results match, a latch signal is generated by the latch signal generation circuit 617, and the latch signal is transmitted to the slave communication IC 6 via the signal line.
00 to the output driver 604
Reference numeral 04 latches transmission data of the buffer 603 and outputs data (DOUT) to the motor. If the comparison results do not match, no latch signal is sent from the latch signal generation circuit 617, and no data is output from the output driver 604 of the slave communication IC 600.

Host CPU 62 of comparison result notifying section 615
The means for notifying to 0 may be a flag operation by a register or a signal output for an interrupt signal.

When the use of the latch signal generation circuit 606 is selected by the latch signal selection circuit 607, the latch signal generation circuit 606
9, a latch signal is generated at the end of the transmission operation, and the output driver 60 is output in the same manner as the operation described in the first embodiment.
4, the operation of latching the data in the buffer 603 and outputting it to the motor is performed.

According to the present embodiment, when there is an abnormality in the transmission data, the host CPU 620 recognizes the abnormality of the data and can take a recovery action within a short time. If the transmitted data does not match the data received by the slave communication IC 600, no data is output from the output driver 604 of the slave communication IC 600, so that output of abnormal control information is prohibited and illegal operation of the motor or the like is prevented. In addition to the above, the provision of the transmission / reception selection circuit 618 makes it possible to select not to use the function of the data comparison circuit 614. Data communication can be performed by operation, and data check method can be selected according to transmission data or communication system environment. It is possible to have a flexible.

In the first to third embodiments described above, one address has eight bits, and information for eight addresses is transmitted and received between the communication controller and the child communication IC. Depending on the format convention, they can be changed to a suitably optimized configuration. Further, a system can be configured by a plurality of communication controllers, and the load of data to be transmitted and received can be increased by using a plurality of communication lines correspondingly.

[0057]

According to the first and fifth aspects of the present invention, the communication control means continuously performs the transmission operation and the reception operation with respect to the child communication means, and transmits and receives the transmission data and the reception data. Is performed and the result of the comparison is output, so that abnormalities in transmission / reception of communication data and transmission of abnormal data can be quickly and accurately recognized, and the reliability of data communication can be improved. it can.

According to the sixth and tenth aspects of the present invention, the communication control means continuously performs the transmission operation and the reception operation with respect to the child communication means, and compares the transmission data with the reception data. And outputs the comparison result.
When the comparison result matches, a latch signal is sent to the drive means of the child communication means to output the data received by the child communication means. In addition, it is possible to accurately and accurately recognize and improve the reliability of the data communication, and when there is an abnormality in the transmission data, the output from the child communication means can be prohibited. It is forbidden, and it is possible to prevent unauthorized operation of the motor and the like.

According to the eleventh and nineteenth aspects of the present invention, the first latch signal generating means for generating a latch signal when the comparison result between the transmission data and the reception data matches, and the communication control means And the second latch signal generating means for generating a latch signal after the data transmission from the slave communication means and sending it to the drive means of the child communication means can be selected. Transmission can be quickly and accurately recognized, the reliability of data communication can be improved, and one of the parity check at the end of the transmission operation or the comparison between the transmission data and the reception data can be selected. If an abnormality is found in the transmission data as a result, the output from the child communication means can be prohibited, so that the output of abnormal control information is prohibited,
It is possible to prevent unauthorized operation of the motor and the like.

Further, by providing an operation selecting means for selecting a control for continuously performing a transmitting operation and a receiving operation with respect to the child communication means designated by the control means, the function of the comparing means is selectively provided. Since it can be stopped, data communication can be performed by the same transmission operation as that of a conventional serial communication system in an environment with few malfunctions. Can be held.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a main configuration of a conventional serial communication system.

FIG. 2 is a schematic block diagram showing a main configuration of a conventional serial communication system applied to an image forming apparatus such as a copying machine.

FIG. 3A is a diagram showing a data format of a transmission frame in a conventional serial communication system. (B)
FIG. 1 is a diagram showing a data format of a reception frame of a conventional serial communication system.

FIG. 4 is a block diagram showing a main configuration of a synchronous serial communication system according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing a main configuration of a synchronous serial communication system according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a main configuration of a synchronous serial communication system according to a third embodiment of the present invention.

[Explanation of symbols]

 400, 500, 600 Child communication ICs 401, 501, 601 Child communication IC control units 402, 502, 602 Shift registers 403, 503, 603 Buffers 404, 504, 604 Output drivers 405, 505, 605 Reset circuits 406, 606 Latch Signal generation circuit 409, 509, 609 Communication controller 410, 510, 610 Communication controller control unit 411, 511, 611 Shift register 412, 512, 612 Transmission buffer 413, 513, 613 Receiving buffer 414, 514, 614 Data comparison circuit 415 , 515, 615 Comparison result notification unit 420, 520, 620 Host CPU 607 Latch signal selection circuit 618 Transmission / reception selection circuit

Claims (19)

[Claims] 1. A synchronous serial communication system comprising: communication control means for controlling communication; and slave communication means connected to the communication control means via a communication line for transmitting and receiving data to and from the communication control means. In the communication system, the communication control unit includes a first storage unit that holds transmission data, a second storage unit that stores reception data from the child communication unit, and data of the first storage unit. Comparison means for comparing the data with the data in the second storage means, wherein the slave communication means has a third storage means for holding data received from the communication control means, and a data in the third storage means. The slave communication control means continuously performs a transmission operation and a reception operation with respect to the communication means, and the comparison means compares the data of the first storage means with the data of the first storage means. 2 memory hands 2. A synchronous serial communication system, comprising: comparing with data of a stage; and outputting a result of the comparison. 2. The communication control means has a first shift register for transmitting and receiving data of the first storage means and data of the second storage means, respectively, and the child communication means comprises: 2. The synchronous serial communication system according to claim 1, further comprising a second shift register for transmitting and receiving data of said third storage means. 3. The synchronous serial communication system according to claim 1, wherein a plurality of said child communication means are connected to said communication line, and said communication control means communicates with said designated child communication means. 4. The slave communication means includes a latch signal generation means for generating a latch signal after transmission of data from the communication control means and sending the latch signal to the drive means,
The drive means is responsive to the latch signal to generate the third
2. The synchronous serial communication system according to claim 1, wherein data of said storage means is output. 5. A synchronous serial communication system comprising: communication control means for controlling communication; and slave communication means connected to the communication control means via a communication line for transmitting and receiving data to and from the communication control means. In the control method for a communication system, a holding step of holding transmission data from the communication control unit in a first storage unit of the communication control unit; a transmission step of transmitting the transmission data to the child communication unit; A data storage step of storing data in a third storage means of the child communication means, a data output step of outputting data of the third storage means, and a data communication step of transmitting data stored in the third storage means to the child communication means Receiving from the means to the communication control means, storing the received data from the slave communication means in the second storage means of the communication control means, The communication control means includes a comparison step of comparing data of the first storage means and data of the second storage means, and a comparison result output step of outputting the comparison result, wherein the transmission step and the reception A control method for a synchronous serial communication system, wherein the steps are executed successively, the comparison step is executed, and the comparison result is output. 6. A synchronous serial communication system comprising: communication control means for controlling communication; and slave communication means connected to the communication control means via a communication line and transmitting and receiving data to and from the communication control means. In the communication system, the communication control unit includes a first storage unit that stores transmission data, and a second storage unit that stores reception data from the communication unit.
Storage means, the data in the first storage means and the second
And a latch signal generating means for generating a latch signal when the result of comparison by the comparing means matches, and wherein the slave communication means receives data from the communication control means. A third storage unit for holding data; and a drive unit for outputting data from the third storage unit. The communication control unit continuously performs a transmission operation and a reception operation with respect to the child communication unit. The comparison means compares the data in the first storage means with the data in the second storage means, outputs the comparison result, and generates the latch signal when the comparison result matches. Means for transmitting said latch signal to said drive means to output data of said third storage means. 7. The communication control means has a first shift register for transmitting and receiving data of the first storage means and data of the second storage means, respectively, and the child communication means comprises: 7. The synchronous serial communication system according to claim 6, further comprising a second shift register for transmitting and receiving data of said third storage means. 8. The synchronous serial communication system according to claim 6, wherein a plurality of said child communication means are connected to said communication line, and said communication control means communicates with said designated child communication means. 9. The synchronous serial communication system according to claim 6, wherein said latch signal generation means and said drive means are connected by a signal line. 10. A synchronous serial communication system comprising: communication control means for controlling communication; and slave communication means connected to the communication control means via a communication line and for transmitting and receiving data to and from the communication control means. In the control method for a communication system, a holding step of holding transmission data from the communication control unit in a first storage unit of the communication control unit; a transmission step of transmitting the transmission data to the child communication unit; A storing step of storing data in a third storage means of the communication means, a data output step of outputting data of the third storage means, and a step of transmitting data stored in the third storage means to the child communication means Receiving the data from the slave communication means in the second storage means of the communication control means; The communication control means includes a comparison step of comparing data of the first storage means with data of the second storage means, and a latch signal generation step of generating a latch signal when the comparison results match. Executing the transmitting step and the receiving step successively, executing the comparing step, outputting the comparison result, and generating the latch signal by the latch signal generating step when the comparison result matches. And outputting the data of the third storage means in the data output step. 11. A synchronous serial communication system comprising: communication control means for controlling communication; and slave communication means connected to the communication control means via a communication line for transmitting and receiving data to and from the communication control means. In the communication system, the communication control unit includes a first storage unit that stores transmission data, and a second storage unit that stores reception data from the communication unit.
Storage means, the data in the first storage means and the second
And a first latch signal generation unit that generates a latch signal when the comparison result by the comparison unit matches, the child communication unit includes the communication control unit. A storage unit for holding data received from the communication unit, a drive unit for outputting data from the third storage unit, and a latch signal generated after the data transmission from the communication control unit is completed. Second latch signal generating means for transmitting
Latch signal input means for inputting a latch signal from outside;
And a latch signal selecting means for selecting a latch signal from the second latch signal generating means or a latch signal from the latch signal input means. 12. The communication control means has a first shift register for transmitting and receiving data of the first storage means and data of the second storage means, respectively, and the child communication means comprises: 12. The synchronous serial communication system according to claim 11, further comprising a second shift register for transmitting and receiving data of said third storage means. 13. The synchronous serial communication system according to claim 11, wherein a plurality of said child communication means are connected to said communication line, and said communication control means communicates with said designated child communication means. 14. The communication control means, wherein the comparison means compares the data in the first storage means with the data in the second storage means, and outputs a result of the comparison. The synchronous serial communication system according to claim 11. 15. The first latch signal generating means and the latch signal input means are connected by a signal line, and when the latch signal from the latch signal input means is selected by the latch selecting means, the comparing means. 12. A latch signal is sent from the first latch signal generation means to the drive means when the comparison result of the first and second latch signals matches, and data of the third storage means is output.
A synchronous serial communication system as described. 16. The second circuit according to claim 16, wherein
When the latch signal from the latch signal generation means is selected, after the data transmission from the communication control means is completed, a latch signal is generated by the second latch signal generation means and transmitted to the drive means, The drive means
12. The synchronous serial communication system according to claim 11, wherein data of said third storage means is output according to said latch signal. 17. The communication control means continuously performs a transmission operation and a reception operation with respect to the child communication means, and uses the comparison means to store the data in the first storage means and the second storage means. 12. The synchronous serial communication system according to claim 11, wherein the synchronous serial communication system compares the data with the data of (1) and outputs the comparison result. 18. The communication control unit includes an operation selection unit that selects an operation of continuously performing a transmission operation and a reception operation with respect to the child communication unit, and performs the transmission operation and the reception operation continuously. 12. The synchronous serial communication system according to claim 11, wherein when no operation is selected, the operation of the comparing means is prohibited. 19. A synchronous serial communication system comprising: communication control means for controlling communication; and slave communication means connected to the communication control means via a communication line and configured to transmit and receive data to and from the communication control means. In the control method for a communication system, a holding step of holding transmission data from the communication control unit in a first storage unit of the communication control unit; a transmission step of transmitting the transmission data to the child communication unit; A data storage step of storing data in a third storage means of the child communication means, a data output step of outputting data of the third storage means, and a data communication step of transmitting data stored in the third storage means to the child communication means Receiving from the means to the communication control means, storing the received data from the slave communication means in the second storage means of the communication control means, A comparing step of comparing the data of the first storage means with the data of the second storage means in the communication control means; and generating a first latch signal for generating a latch signal when the comparison results match. Steps and
A second latch signal generating step of generating a latch signal after the transmission of data from the communication control means and outputting the data of the third storage means, a latch signal inputting step of externally inputting a latch signal, A latch signal selection step of selecting a latch signal generated by a second latch signal generation step or a latch signal input to the latch signal input step.