JPH07212432A - Data repeater - Google Patents

Abstract

PURPOSE:To restart data transmission when the power source of a data repeater for performing data transmission with a controller based on instructions from a computer is interrupted during the data transmission and is recovered. CONSTITUTION:At the time of activation, an initial state flag Fi is set at '1' and a response request 'ENQ' is transmitted from this data repeater 2 to the computer 1. Until a response to the response request 'ENQ' is received from the computer 1, the response request 'ENQ' is transmitted while changing a transmission speed BPS successively from the high speed to the low speed of a temporary transmission speed Bx set beforehand. When the response to the response request 'ENQ' is received from the computer 1, in the data repeater 2, the temporary transmission speed Bx at the time is set as the transmission speed BPS with the computer 1. In the computer 1, the initial state flag Fi added to the response request 'ENQ' is referred to it is recognized that the data repeater 2 is in an initial activation state and prescribed setting data are transmitted to the data repeater 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data relay device for connecting a computer such as a microcomputer and a control device such as a sequencer.

[0002]

2. Description of the Related Art Conventionally, RS is used when connecting a microcomputer and a control device, such as when connecting a microcomputer and a sequencer using a dedicated line.
Data transmission is performed by serial transmission using a 232C interface, and data transmission is performed by a non-procedure method or a transmission control procedure by a simple transmission procedure method. Further, the RS232C interface is vulnerable to noise and has a drawback that the transmission distance cannot be lengthened. Therefore, the RS422 interface or the RS48 interface is used.
In some cases, data transmission is performed by using the five interfaces.

Generally, a computer such as a microcomputer and a device such as a sequencer are RS485 by using a dedicated line.
When connecting with an interface etc. and performing full-duplex serial transmission, it is necessary to set the same transmission speed between them, and the computer sets the transmission speed at the time of setup or when starting serial transmission. And set
In the sequencer, the transmission speed is set by a hardware setting switch.

Data transmission control between the computer and the sequencer may be performed on the sequencer side or by a data relay device arranged between the computer and the sequencer. Which device controls the data transmission. It is designed to be used properly depending on the purpose. When the data relay device is started, the transmission rate is set to a preset default value. When the data relay device controls data transmission between the computer and the sequencer, a value other than the default value is set. When performing data transmission at the transmission rate, first, the computer outputs the transmission rate setting information to the data relay apparatus, and the data relay apparatus changes the transmission rate based on the input transmission rate setting information. Then, in the computer, the data transmission is performed after changing the transmission speed to a desired one and changing the transmission speeds of the computer and the data relay device to be the same.

[0005]

However, in the above-mentioned conventional data relay apparatus, since the default value of the transmission rate is set at the time of startup, the default value is not set between the computer and the data relay apparatus. When data is transmitted at different transmission speeds, for example, if the power of the data relay device is cut off due to a power failure or the like and then resumes, the transmission speed of the data relay device is the preset transmission speed. Is set to the default value of, and at this time, the transmission speed before the power is cut off is set for the computer, so the transmission speed differs between the computer and the data relay device, and the computer and the data relay device There is an unsolved problem that data cannot be transmitted between the two.

Further, since the computer cannot recognize that the transmission rate of the data relay device has been changed, it is recognized as a transmission error even though the set transmission rates are different. However, there is also a problem that it is determined that the transmission abnormality continues to occur.
In the data transmission between the data relay device and the sequencer, when the data relay device is operating in the master mode and the data relay device loses power due to power failure or the like and then recovers, the data relay device Since the operation mode of is set to the slave mode which is the default value, there is an unsolved problem that the data transmission with the sequencer cannot be performed thereafter and the data reading and writing of the sequencer cannot be performed.

Therefore, the present invention has been made by paying attention to the above-mentioned unsolved problems of the related art, and a power failure or the like causes a power failure during data transmission between a computer and a control device.
It is an object of the present invention to provide a data relay device that can reliably restart data transmission even when it returns after that.

[0008]

In order to achieve the above object, the data relay apparatus according to claim 1 has the configuration shown in FIG.
As shown in the basic configuration diagram of the above, in a data relay device that exchanges data with a control device based on a command from a host computer, at start-up, by changing the transmission speed until a response is obtained from the host computer, a response request character And a transmission rate setting means for setting a transmission rate at that time as a transmission rate with the host computer when a response to the response request character is received from the host computer. I am trying.

Further, in the data relay apparatus according to the second aspect, the response request character according to the first aspect is provided with an initial information area for storing initial activation information of the data relay apparatus.

[0010]

For example, in a data relay device for exchanging data with a control device based on a command from a host computer, a response request character is transmitted to the host computer by the transmitting means at startup, and a response to the transmitted response request character is sent to the host computer. The transmission speed is changed until the data is obtained from the computer, and when the response from the host computer is obtained, the transmission speed setting means determines the transmission speed at that time as the data transmission rate with the host computer. However, at this time, by setting the initial activation information that the data relay device is in the initial activation state in the initial information area provided in the response request character, the computer side confirms that the data relay device is in the initial activation state. recognize.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing an embodiment of a data transmission system using the data relay device according to the present invention. The data relay device 2 is connected to a computer 1 as a host computer such as a microcomputer by a dedicated line L1 and R
Bidirectional data transmission is performed by the S485 interface, and the sequencer 3 and the dedicated line L2 are connected.

The sequencer 3 is connected to a sequence controller 31, an external device 10 for detecting an operation command from the outside and a state of a controlled object, an input capsule 32 for fetching conditions necessary for sequence control, and a controlled object. Of the external device 10 and the like, which outputs a control command, and, for example, a micro controller 34 which is connected to another sequencer and controls data transmission between the sequencers.
The input capsule 32, the output capsule 33, and the microcontroller 34 are connected by a dedicated line L3 such as a twisted pair cable, and the sequence controller 31 is based on the input data from the external device 10 input via the input capsule 32. Performs predetermined arithmetic processing in
The processing result is output to the external device 10 via the output capsule 33, and data is transmitted to another sequencer or the like via the microcontroller 34.

The data relay device 2 communicates with the computer 1 according to a predetermined communication control procedure, receives transmission data such as an instruction to read / write data of the sequencer 3 from the computer 1, and the received transmission data is the sequencer 3 If it is a data transmission command to the computer 1, the transmission data from the computer 1 is transmitted to the sequence controller 31, and after the transmission is completed, the transmission result is transmitted to the computer 1. If the transmission data from the computer 1 is a data read command for the sequencer 3, the designated data is read from the sequence controller 31, and after the reading is completed, the communication result with the sequence controller 31 and the read data are displayed. Calculator 1
Send to.

When the data relay apparatus 2 is started, the data relay apparatus 2 sends a response request "ENQ" as a response request character added with its own initial activation information to the computer 1, and a response to the response request "ENQ" is sent from the computer 1. Until you receive
The transmission rate is changed and the response request "ENQ" is transmitted. FIG. 3 shows a transmission control procedure between the computer 1 and the data relay apparatus 2.

When data is transmitted from the computer 1 to the data relay device 2, as shown in FIG. 3A, first, the computer 1 sends a response request "EN" to the data relay device 2.
Q ”is transmitted. In the data relay device 2, the response request“ E ”is sent.
As a response to NQ, if the transmission data from the computer 1 can be received, an affirmative response “ACK” is transmitted, and if it cannot be received, a negative response “NAK” is transmitted.

When the computer 1 receives the positive response "ACK" from the data relay apparatus 2, the computer 1 starts transmission of the transmission data, and the data relay apparatus 2 is followed by a predetermined text start character "STX" and then a predetermined number. The transmission end data is transmitted, and after the transmission of the transmission data is completed, the text end character "ETX" is transmitted. In the data relay device 2, when the end-of-text character "ETX" is received, the input transmission data is checked for a transmission error or the like. If a transmission error occurs in the received transmission data, the computer 1
If a negative response "NAK" is sent to the device and no transmission error occurs in the transmission data, the positive response "ACK" is sent assuming that the communication is normally performed.

When the computer 1 receives the affirmative response "ACK", it determines that the data transmission is normally performed, and terminates the data transmission. Here, if the computer 1 does not receive any response from the data relay device 2 within a predetermined time after transmitting the transmission data and transmitting the text end character “ETX”, the data transmission is normally performed. If not, the data transmission process is performed in the same manner as described above, the response request “ENQ” is transmitted to the data relay device 2 again, and when the positive response “ACK” is received, transmission of the transmission data is started. .

On the contrary, when data is transmitted from the data relay device 2 to the computer 1, contrary to the above, as shown in FIG.
As shown in FIG. 3, the data relay device 2 transmits a response request “ENQ” to the computer 1, and the computer 1 responds to the response request “ENQ” if the transmission data can be received, an affirmative response “ACK”. Is transmitted, and if it cannot be received, a negative response “NAK” is transmitted.

When the data relay device 2 receives an affirmative response "ACK" from the computer 1, the data relay device 2 starts transmitting the transmission data, transmits the predetermined transmission data after the text start character "STX", and transmits the predetermined transmission data. When the transmission of the transmission data is completed, the text end character "ETX" is transmitted. When the computer 1 receives the end-of-text character "ETX" from the data relay device 2, it performs an error check or the like to check whether the received transmission data has a transmission error or the like, and if there is no transmission error, transmits an acknowledgment "ACK". However, if there is a transmission error, a negative response “NAK” is transmitted to the data relay device 2.

In the data relay device 2, the computer 1
When the positive response “ACK” is received from the device, the data transmission process is terminated assuming that the data transmission is normally performed.
On the other hand, when the negative response “NAK” is received from the computer 1, the data relay device 2 transmits the response request “ENQ” to the computer 1 again, performs the data transmission process in the same manner as above, and transmits the transmission data. Resend.

Here, the transmission control characters such as the response request "ENQ" and the positive response "ACK" have the structure shown in FIG. 4, and the response request "ENQ" is shown in FIG. 4 (a).
As shown in, ENQ consists of 1 byte each, ENQ
The code C _ENQ , the SA code C _{SA including} the address of the transmission source station and the initial status flag Fi as the initial activation information, and the LF code C _LF indicating the end of the transmission control character are selected in this order from 3 bytes. It is formed from the least significant byte.

As shown in FIG. 4B, the SA code C _SA has the least significant bit of 0 bit and the most significant bit of 7 bit, and the initial state flag Fi at the 3rd bit as the initial information area. Is stored, and the address of the transmission source station is stored in the 4th to 7th bits. In addition, as shown in FIG. 4C, the acknowledgment “ACK” includes a DLE code C _DLE and an ACK code C _ACK , each of which is composed of 1 byte, for realizing transparent mode data transmission.
It is formed from the least significant byte in this order from the 3 bytes of the LF code C _LF, and similarly, the negative response “NAK” is shown in FIG.
As shown in (d), each consists of 1 byte,
The DLE code C _DLE , the NAK code C _NAK, and the LF code C _LF are formed from 3 bytes, in this order from the least significant byte.

As shown in FIG. 4 (e), the transmission data includes a DLE code C _DLE each consisting of 1 byte and an STX code C _STX indicating the start of the transmission data.
And LE representing the number of transmission data bytes obtained by adding 4 bytes to the data length of the text data to be transmitted as transmission data.
N code C _LEN , text data code C _DAT with the number of bytes according to the text data length, DEL code C _DEL composed of 1 byte, ETX code C _ETX indicating the end of text data, and transmission The least significant byte is formed in this order from the BCC code C _BCC for error detection and the LF code C _LF .

Next, the operation of the above embodiment is shown in FIG.
An explanation will be given based on a flowchart showing a processing procedure of the data relay device 2 at the time of startup. When the data relay device 2 is activated, first, in step S1, a response request “ENQ” is sent.
The initial state flag Fi is set to "1", and the process proceeds to step S2.

Then, in step S2, the temporary transmission rate B
For example, when n kinds of transmission rates satisfying B1 <B2 <... <Bn are set as the set value of x, the set number “n” of transmission rates is set as the initial value of the count value X,
Control goes to step S3. In step S3, the preset provisional transmission rate Bx is provisionally set as the transmission rate BPS,
In step S4, the response request “ENQ” is transmitted to the computer 1 at the transmission rate BPS provisionally set in step S3, that is, the provisional transmission rate Bx.

Then, in step S5, step S4
It is determined whether or not the response from the computer 1 to the response request "ENQ" transmitted in step S6 has been received within a preset time, and if a response to the response request "ENQ" is received, the process proceeds to step S6. . Then, in step S6, the current transmission rate BPS, that is, the provisional transmission rate Bx is determined as the transmission rate BPS with the computer 1, the initial state flag Fi of the response request "ENQ" is set to "0", and the activation is started. The time processing ends.

On the other hand, in step S5, when the response to the response request "ENQ" from the computer 1 is not received within the preset predetermined time, the process proceeds to step S7 and X
= X−1, the process proceeds to step S8, and it is determined whether or not X = 0. If X = 0, step S3
Returning to step S10, when X = 0, the process proceeds to step S9, it is determined that the transmission abnormality with the computer 1 has occurred, and the process is ended.

Here, steps S1 to S5 and steps S7 to S9 correspond to transmitting means, and step S6 corresponds to transmission rate setting means. So, for example, now
Each device is operating normally, and the sequencer 3 performs a predetermined calculation process based on the input data from the external device 10 via the input capsule 32, and outputs the calculation result via the output capsule 33 to the external device. It is assumed that the operation result is output to 10 and the operation result is output to another sequencer or the like via the microcontroller 34.

Further, as the provisional transmission rate, B1 <B2 <B
It is assumed that the transmission rate satisfying 3 is set. At this time, between the computer 1 and the data relay device 2, a transmission rate BPS different from the default value, for example, B2bps.
The data relay device 2 performs data communication with the sequencer 3 in the master mode, reads the operation processing result of the sequencer 3 based on a command from the computer 1, and displays the read operation processing result. It is assumed that the read data is transmitted to the computer 1.

In this state, for example, it is assumed that the data relay device 2 is cut off due to a power failure or the like. As a result, the power of the data relay device 2 is cut off,
All setting values are set to default values,
It is assumed that the transmission rate BPS is set to B1bps as a default value and the operation mode is set to the slave mode.

When the data relay device 2 is restarted in this state, the data relay device 2 first sets the initial state flag Fi of the response request "ENQ" to "1", and in this case, the temporary transmission is performed. Since three types of transmission rates are set, the provisional transmission rate B3bps, which is the maximum transmission rate, is provisionally set as the transmission rate BPS.
The response request “ENQ” is transmitted to the computer 1 at 3 bps.

At this time, the transmission rate BPS of the computer 1 is
B2bps remains, without returning to the default value,
Since the data relay device 2 transmits at the transmission rate BPS = B3 bps, the computer 1 side cannot receive the response request “ENQ” from the data relay device 2. Therefore, the data relay apparatus 2 cannot receive the response to the response request “ENQ” from the computer 1 within the preset predetermined time, and therefore the computer 1 and the transmission rate BP
It is determined that S is different, then the provisional transmission rate B2 having the next largest transmission rate is set as the transmission rate BPS, and the response request “ENQ” is transmitted to the computer 1 at the transmission rate B2 bps.

At this time, since the transmission rates BPS of the computer 1 and the data relay device 2 are both B2bps, the computer 1 can receive the response request "ENQ" from the data relay device 2 and the response request. A response request “EN” from the data relay device 2 is made by referring to the address information of “ENQ”.
It recognizes that it is "Q", and transmits an affirmative response "ACK" to the data relay device 2 as a response to the response request "ENQ".

Further, the computer 1 refers to the initial state flag Fi of the received response request "ENQ", and since the initial state flag Fi is "1", it recognizes that the data relay device 2 is in the initial starting state. However, for example, the operation mode of the data relay device 2 is the master mode, and various setting data set for the data relay device 2 before the power is turned off is transmitted again to the data relay device 2.

The data relay device 2 receives the positive response "ACK" from the computer 1, and thus determines the transmission rate BPS with the computer 1 as B2bps, and sets the initial state flag Fi of the response request "ENQ" to "0". Then, the mode setting is performed based on the setting data that the operation mode from the computer 1 is the master mode, and the predetermined setting is performed based on various setting data from the computer 1.

As a result, the data relay device 2 is set with the same various setting data as before the power was turned off. Therefore, it becomes possible to perform data communication with the computer 1, and By setting the operation mode as the master mode in the data relay device 2, it becomes possible to read / write data from / to the sequencer 3, and it is possible to reproduce the device state before the power of the data relay device 2 was cut off. The data transmission between the computer 1 and the sequencer 3 can be restarted.

On the other hand, in the data relay apparatus 2, if the response to the response request "ENQ" is not obtained even if the temporary transmission rates B1, B2 and B3 are set as the transmission rate BPS and transmitted, the computer 1 and The communication is determined to be abnormal, and the process ends. Therefore, in the above embodiment, at the time of start-up, the data relay device 2 sets the initial state flag to "1" and temporarily sets the transmission rate BPS to the maximum value of the provisional transmission rate Bx set in advance, and the response request "ENQ". To the computer 1, the transmission speed BPS is sequentially changed to a smaller value of the temporary transmission speed Bx until a response is sent from the computer 1, and a response request “ENQ” is transmitted. Transmission speed Bx is the transmission speed BPS with computer 1.
Therefore, even when the data relay device 2 is powered off and restarted during data transmission between the computer 1 and the data relay device 2, the data relay device 2 searches for the transmission speed BPS of the computer 1 and searches. Transmission speed B
By setting PS as the transmission speed, the data transmission can be restarted without intervention of the operator, and the data transmission is continued on the computer side without worrying about the power failure of the data relay device 2. You can do it.

Further, the data relay device 2 transmits the initial state flag Fi of the response request "ENQ" as "1" to the computer 1 at the time of starting, so that the initial state flag Fi in the computer 1 is "1". It is possible to easily recognize whether or not the data relay device 2 is in the initial state by determining whether the data relay device 2 is in the initial state or not. It is possible to surely recognize that the data relay device 2 is newly activated without recognizing that there is an abnormal transmission with the device 2.

In the above embodiment, the transmission speed B
The PS is set from the one having the higher provisional transmission rate Bx, but it may be set from the one having the lower transmission rate. In the above embodiment, the RS48 between the data relay device and the host computer is used.
The case has been described where full-duplex serial transmission is performed using 5 interfaces, but the present invention is not limited to this, and when data transmission is performed between devices, the same transmission rate is set between both devices and data transmission is performed. If so, it can be applied.

Further, in the above embodiment, the case where the data transmission is performed between the host computer and the data relay device in the transparent mode has been described, but the present invention can be applied even when the data transmission is not performed in the transparent mode.

[0041]

As described above, according to the data relay apparatus of the present invention, in the data relay apparatus for exchanging data with the control unit based on the command from the host computer, the response request is made by the transmitting means at the time of starting. The character is sent to the host computer, the transmission speed is sequentially changed until a response is received from the host computer, and when the response request character is sent, the initial of the data relay device is set in the activation information area provided in the response request character. By adding start information and transmitting it, even if the data relay device is powered off during data transmission and restarted after that, data transmission between the computer and the control device can be reliably restarted, and , The computer can easily recognize the initial activation state of the data relay device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a basic configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a communication control procedure between a computer and a data relay device.

FIG. 4 is an explanatory diagram showing a structure of a transmission control character.

FIG. 5 is a flowchart showing a processing procedure when the data relay device is activated.

[Explanation of symbols]

 1 Computer 2 Data Relay Device 3 Sequencer 31 Sequence Controller 32 Input Capsule 33 Output Capsule Fi Initial State Flag

Claims (2)

[Claims] 1. A data relay device for transmitting and receiving data to and from a control device based on a command from a host computer, at the time of startup, transmitting a response request character by changing a transmission rate until a response is obtained from the host computer. And a transmission rate setting means for setting a transmission rate at that time as a transmission rate with the host computer when a response to the response request character is received from the host computer. apparatus. 2. The data relay device according to claim 1, wherein the response request character includes an initial information area for storing initial activation information of the data relay device.