JPH0918504A - Data communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve the reliability of a data communication by enabling interruption data of high priority to be transmitted without being broken during normal communication processing for the transmission and reception of request data and response data. SOLUTION: The normal communication processing uses 1st data formed of a 1st potential V1 and a 2nd potential V2. For interruption communication processing for transmitting interruption data of higher priority than the normal communication processing, 2nd data formed of the 1st potential V1 and a 3rd potential V3 lower than the 2nd potential V2 are used. Even when the 1st data and 2nd data overlap with each other, the 1st data is destroyed, but the 2nd data is destroyed only partially and a terminal equipment can detect the 2nd data without any influence. Consequently, the data of high priority can be sent and received and the reliability of the data communication is greatly improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication device suitable for data communication between a plurality of ECUs (Electronic Control Units) mounted on a vehicle.

[0002]

2. Description of the Related Art FIG. 1 is a block diagram showing an overall configuration of a data communication apparatus 1 which is a premise of the present invention. The data communication device 1 is configured to include one master terminal device M and a plurality of slave terminal devices S1 to Sn (reference numeral S is used when collectively referred to). The terminal devices M and S are connected by a communication line K. Data communication device 1
In accordance with ISO 9141 (international standard), a communication method is implemented. This communication system is a so-called master / slave system, in which request data is transmitted from the master terminal device M to a plurality of slave terminal devices S, each slave terminal device S receives the request data, and each slave terminal device S receives the request data. In this method, S transmits response data to the master terminal device M. The transmission of request data from the master terminal device M and the transmission of response data from the slave terminal device S constitute one cycle of normal communication processing.

The slave terminal devices S1 to Sn have a predetermined priority order, and the response data is transmitted to the master terminal device M in order from the slave terminal device having the higher priority order. Here, the subscripts 1 to n of the reference symbol S represent the priority order. The terminal devices M and S set the communication line K, which is set to the predetermined first potential (high level) in the standby state, to the second predetermined lower than the first potential.
The means for lowering the potential (low level) of
Bit data is created by switching one level at a predetermined timing, and the data is transmitted. Byte data is composed of a predetermined number of bit data, and message data is composed of a predetermined number of byte data. This message data corresponds to the request data and the response data.

[0004]

In the data communication device 1 in which the master / slave system is implemented, during the normal communication process currently being performed, another communication cannot be executed until the communication process is completed. . If another communication is forcibly attempted to perform communication for notifying the master terminal device M that an abnormality has occurred in the terminal device as high-priority communication, the two data overlap and the two data together. There is a problem that the data will be destroyed and data communication cannot be performed normally.

An object of the present invention is to enable interrupt data having a higher priority than request data and response data to be transmitted without being destroyed during normal communication processing for transmitting and receiving request data and response data. An object of the present invention is to provide a data communication device in which the reliability of data communication is significantly improved.

[0006]

According to the present invention, a main terminal device is selected from a plurality of terminal devices by connecting a plurality of terminal devices with one communication line in which a predetermined first potential is in a standby state. Is a data communication device that transmits request data to another terminal device, and the other terminal device sequentially transmits response data to the request data in accordance with a predetermined priority order that determines the order of data transmission to the main terminal device. In the above, each terminal device sets the potential of the communication line to the first potential and the first potential.
A second data potential that is switched to a predetermined second potential that is lower than the first potential to generate and transmit the first data, and the potential of the communication line from the first potential and the second potential. Second data transmitting means for generating and transmitting second data by switching to a predetermined third potential which is also low, and data reception for detecting the potential of the communication line and receiving the first and second data. Means for transmitting the request data by the main terminal device and the response data by the other terminal device, the normal communication process is performed by using the first data. In the data communication device, the second data is used when performing the interrupt communication process that transmits the interrupt data that has priority over the normal communication process. According to the present invention,
A plurality of terminal devices are connected by one communication line, and as a normal communication process, a main terminal device selected from a plurality of terminal devices transmits request data and another terminal device responds to the request data. And send. In the normal communication processing, the first data created by the first data transmitting means by switching the potential of the communication line between the first potential in the standby state and the predetermined second potential lower than the first potential. Is done using. During the normal communication process, when performing the interrupt communication process for transmitting the interrupt data prioritized over the normal communication process, the potential of the communication line is set to the first potential in the standby state by the second data transmitting means. It is performed using the second data created by switching to a predetermined third potential lower than the second potential. If the interrupt data and request data or response data overlap,
Since the third potential forming the interrupt data is lower than the second potential forming the request data and the response data, the request data and the response data will be corrupted, but the interrupt data must be received without being corrupted. You can This makes it possible to reliably transmit and receive interrupt data having a higher priority than the normal communication processing, for example, an error signal, and improve the reliability of data communication.

Further, according to the present invention, when the interrupt communication process is interrupted during the normal communication process, each terminal device interrupts the normal communication process, and the main terminal device finishes the interrupt communication process. After that, the request data in the interrupted normal communication process is transmitted again. When each terminal device interrupts the normal communication process during the normal communication process, the normal communication process is interrupted, and after the interrupt communication process is completed, the main terminal device returns the request data in the normal communication process again. Send. As a result, the normal communication process interrupted by the interrupt communication process is restarted, so that the interrupt communication process and the normal communication process can be smoothly performed, and the reliability is further improved.

According to the present invention, each terminal device interrupts the normal communication process when the interrupt communication process interrupts during the normal communication process, and interrupts after the interrupt communication process is completed. The feature is that normal communication processing is restarted. The normal communication process interrupted by the interrupt of the interrupt communication process is restarted from the point at which it was interrupted after the interrupt communication process was completed, so compared to the case of restarting from the beginning after the interruption.
Communication time can be reduced.

According to the present invention, each terminal device switches to the first data and performs the interrupt communication process after the transmission and reception of the first at least 1-bit data of the interrupt communication process is completed. Characterize. After the first at least 1-bit data of the interrupt communication process is transmitted and received by the second data, the interrupt communication process is performed by switching to the first data. Therefore, even if an interrupt communication process that transmits interrupt data with a higher priority during the interrupt communication process interrupts, it is possible to receive interrupt data with a higher priority without destroying it. it can. This improves the reliability of data communication. Further, it is not necessary to prepare a transmitting means for transmitting data composed of a plurality of different potentials according to the priority, and the structure can be downsized and the cost can be reduced.

According to the present invention, the data receiving means may detect whether the potential of the communication line is higher or lower than a first reference potential selected between the first and second potentials.
Potential detecting means and second potential detecting means for detecting whether the potential of the communication line is higher or lower than the second reference potential selected between the second and third potentials. The device is characterized by determining that an error has occurred when the detection results of the first and second potential detecting means do not match. When the detection results by the first and second potential detecting means included in the data receiving means do not match,
Judge that an error has occurred.

[0011]

1 is a block diagram showing an overall configuration of a data communication apparatus 1 which is a premise of the present invention. The data communication device 1 is configured to include one master terminal device M and a plurality of slave terminal devices S1 to Sn (reference numeral S is used when collectively referred to). Terminal device M, S
Are connected by a communication line K. The data communication device 1 implements a communication method that complies with ISO9141 (International Standard). This communication system is a so-called master / slave system, in which request data is transmitted from the master terminal device M to a plurality of slave terminal devices S, each slave terminal device S receives the request data, and each slave terminal device S receives the request data. In this method, S transmits response data to the master terminal device M. The transmission of request data from the master terminal device M and the transmission of response data from the slave terminal device S constitute one cycle of normal communication processing.

The slave terminal devices S1 to Sn have a predetermined priority order, and the response data is transmitted to the master terminal device M in order from the slave terminal device having a higher priority. Here, the subscripts 1 to n of the reference symbol S represent the priority order. The terminal devices M and S set the communication line K, which is set to the predetermined first potential (high level) in the standby state, to the second predetermined lower than the first potential.
And a means for lowering the potential to a third potential (low level), and by switching the high level and the low level at a predetermined timing, bit data is created and the data is transmitted. Byte data is composed of a predetermined number of bit data, and message data is composed of a predetermined number of byte data. This message data corresponds to the request data and the response data.

FIG. 2 is a block diagram showing a schematic configuration of the terminal devices M and S. The terminal devices M and S are configured to include the control circuit 2 and the communication circuit 10. The control circuit 2 includes a main control unit 11 and a communication control unit 12. The main control unit 11 is actually realized by a desired application program (control software), executes the process given to each terminal device, and exchanges commands and data with the communication control unit 12. Communication control unit 12
Is actually realized by a desired program (communication software), transmits commands and data to the communication line K through the communication circuit 10, and transmits and receives commands and data from the communication line K. The master terminal device M outputs the requested data to a data reading device such as a tester (not shown) connected from the outside.

The operation during communication will be briefly described with reference to FIG. The main control unit 11 of the master terminal device M gives a communication request to the communication control unit 12 at a predetermined timing. The communication control unit 12 sends the request data to the communication line K via the communication circuit 10. Communication circuit 1 of slave terminal device S
0 receives the request data and gives it to the communication control unit 12.
The communication control unit 12 gives a response processing request corresponding to the received request data to the main control unit 11. The main control unit 11 executes a process according to the given response process request, and gives the process result to the communication control unit 12. The communication control unit 12 sends the processing result to the communication line K as response data via the communication circuit 10. The response data is realized by the communication circuit 10 of the master terminal device M and given to the communication control unit 12. The communication control unit 12 gives the communication result for the communication request to the main control unit 11. This completes one cycle of communication processing.

FIG. 3 is a block diagram showing a configuration relating to the communication circuit 10 of the terminal devices M and S, which is an embodiment of the present invention. The terminal devices M and S are implemented by, for example, an ECU, and include a control circuit 2 that executes data transmission and reception, various calculations, and various controls. The control circuit 2 is realized by a microcomputer or the like and includes two serial data input terminals Sin0 and Sin1 and two serial data output terminals Sout0 and Sout1.

The terminal devices M and S have a connection terminal 3 for connecting the communication line K. The power supply potential + B of the data communication device 1 is applied to the communication line K via the resistor R1 and set to a predetermined first potential (high level). The first potential of the communication line K is in a standby state. Serial data output terminals Sout0 and Sout1 are connected to the connection terminal 3 via the data transmission circuit 4,
Further, serial data input terminals Sin0 and Sin1 are connected via the data receiving circuit 5. Communication circuit 1 described above
0 includes a data transmission circuit 4 and a data reception circuit 5.

The data receiving circuit 4 includes two switches 6,
7 and resistor R2. The switch 6 has one terminal grounded and the other terminal connected to the connection terminal 3 (communication line K) via the resistor R2. The opening and closing of the switch 6 is controlled by a signal from the serial data output terminal Sout0 of the control circuit 2. When the switch 6 is closed, the potential of the communication line K is + B · R2 / (R1 + R) which is the second potential.
It is lowered to 2). Thereby, the first data is created and transmitted. The switch 7 has one terminal grounded and the other terminal connected to the connection terminal 3 (communication line K). The opening and closing of the switch 7 is controlled by a signal from the serial data output terminal Sout1 of the control circuit 2. When the switch 7 is closed, the potential of the communication line K is lowered to the ground potential which is the third potential. Thereby, the second data is created and transmitted.

The data receiving circuit 5 includes two comparators 8 and 9 and three resistors R3, R4 and R5. Resistance R
3, R4 and R5 are connected in series between the power supply potential + B and the ground potential in this order. The potential at the connection point P1 between the resistors R3 and R4 is + B · (R4 + R5) / (R3
+ R4 + R5), and this potential is given to the comparator 8 as the first reference potential. The comparator 8 has
The connection terminal 3 (communication line K) is connected, and the communication line K
Of the potential of the control circuit 2 is compared with the first reference potential, and the comparison result is compared with the serial data input terminal S of the control circuit 2.
Output to in0. The potential at the connection point P2 between the resistors R4 and R5 is + B · R5 / (R3 + R4 + R5), and this potential is given to the comparator 9 as the second reference potential. A connection terminal 3 (communication line K) is connected to the comparator 9, which compares whether the potential of the communication line K is higher or lower than the second reference potential, and the comparison result is the serial data input terminal Sin1 of the control circuit 2. Output to. The control circuit 2 has serial data input terminals Sin0 and Sin.
Based on the input status of 1, it is determined whether it is the first data or the second data.

FIG. 4 is a time chart showing an example of the structure of message data. The message data corresponds to request data and response data. The message data is
It is composed of a plurality of byte data SOM, D1 to Dn, and EOM. The byte data SOM is data indicating the start of message data. The byte data D1 to Dn are data to be actually transmitted. The byte data EOM is
It is data indicating the end of the message data. Message data in the normal communication process is transmitted using the first data formed by the first potential and the second potential.

FIG. 5 is a waveform diagram of data used in the data communication device 1. FIG. 5A is a waveform diagram of the first data. The first data is the first potential V1 (= +
It is created by switching between B) and the second potential V2 at a predetermined timing. The reference potential Vth1 is the reference potential of the comparator 8, and the reference potential Vth2 is the reference potential of the comparator 9. In the comparator 8, since the reference potential Vth1 is selected between the first potential V1 and the second potential V2, the potential of the communication line K is the first potential Vth.
Each time the voltage is switched between 1 and the second potential V2, the level of the potential is detected, and the detection result is the serial data input terminal Sin.
0, output to Sin1. Since the reference potential Vth2 is selected lower than the potential V2, the comparator 9 always detects that the potential of the communication line K is high and outputs the detection result to the serial data input terminal Sin1. Control circuit 2
Recognizes that it is the first data based on the two detection results.

FIG. 5B is a waveform diagram of the second data. The second data is the first potential V1 and the third potential V3.
It is created by switching to (= ground potential) at a predetermined timing. The first potential V1 is selected higher than the reference potentials Vth1 and Vth2, and the third potential Vth is selected.
Since 3 is selected lower than the reference potentials Vth1 and Vth2, the comparators 8 and 9 detect the high and low potentials each time the first potential V1 and the third potential V3 are switched, and the detection result is obtained. Are the same. The detection results are given to the serial data input terminals Sin0 and Sin1 of the control circuit 2, respectively. The control circuit 2 recognizes that it is the second data because the two detection results match.

FIG. 5C is a waveform diagram when the first data and the second data overlap each other. When the first data and the second data overlap, the communication line K is pulled down to a lower potential, so that the first data is destroyed as shown by the chain double-dashed line, but the second data is Only the part is broken, the detection operation of the comparators 8 and 9 is not affected, and the control circuit 2 can accurately receive the second data.

FIG. 6 is a flow chart showing the processing when the control circuit 2 receives data. At step a1, it is determined whether or not there is an interrupt at the serial data input terminal Sin1. If there is an interrupt, it is determined that the second data has been received. If there is no interrupt, the process proceeds to step a2, and it is determined whether or not there is an interrupt at the serial data input terminal Sin0. If there is an interrupt, it is determined that the first data has been received, and if there is no interrupt, it is determined that the data has not been received.

FIG. 7 is a time chart showing the first communication operation performed by the data communication apparatus 1. 7 (1) shows changes in the potential on the communication line K, FIG. 7 (2) shows data transmitted from the master terminal device M, and FIG.
(6) shows the data transmitted by each of the slave terminal devices S1 to S4. In the normal communication process, the master terminal device M
Based on the request data from the slave terminal devices S1 to S
4 sequentially transmits response data corresponding to the request data in accordance with the priority order.

However, if an error or the like occurs in the slave terminal device S4 and interrupt data having a higher priority than the normal communication process, for example, interrupt communication for transmitting an error signal is required, the slave The terminal device S4 starts the interrupt communication as shown in FIG. 7 (6) even while the response data of the slave terminal device S2 is being transmitted. As a result, as shown in FIG. 7A, in the communication line K, the response data from the slave terminal device S2 and the interrupt communication data from the slave terminal device S4 overlap each other, and each terminal device is overrun due to the collision of two data. A run error or a framing error occurs, and the error causes a reception interrupt in the master terminal device M.

When the reception interrupt occurs, the master terminal device M erases all the response data transmitted from the slave terminal device in the normal communication process, monitors the end of the interrupt communication, and confirms that the interrupt communication is completed. After the confirmation, the request data (re-request data) is transmitted again in order to restart the interrupted normal communication process. Whether or not the interrupt communication is completed is determined by the fact that the bus idle time, which is the time during which the communication line K is kept in the standby state for a certain period, has continued for a predetermined period or more, or the stop message data indicating the completion of the interrupt communication is received. Make decisions based on that.

FIG. 8 is a flow chart for explaining the operation of the master terminal device M in the first communication operation. In step b1, the communication control unit 12 determines whether or not the communication request from the main control unit 11 has been received. When the communication request is received, the process proceeds to step b2, and the communication control unit 12 starts the communication. That is, the communication initial state is set. At step b3, the serial data input terminal Sin
1 determines whether there is an interrupt communication. If there is an interrupt communication, the process proceeds to step b8 described later, and if there is no interrupt communication, the process proceeds to step b4.

At step b4, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step b2 to perform communication again. If no error has occurred, the process proceeds to step b5 to execute the communication process. That is, predetermined request data is transmitted, or response data from the slave terminal device S is received. The response data is received using the serial data input terminal Sin0.

At step b6, it is judged whether or not the communication processing is completed. If not completed, the process returns to step b3 to continue the communication process. When the communication process is completed, the process proceeds to step b7, the received response data is delivered to the main control unit 11, and the process is completed.

At step b8, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step b2 to perform communication again. If no error has occurred, the process proceeds to step b9 to execute the interrupt communication process. That is, the request data from the slave terminal device S in which the interrupt processing has occurred is received, or the response data corresponding to the request data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin0. At step b10, it is determined whether or not the communication process is completed.
If not completed, the process returns to step b8 to continue the interrupt communication process. When the communication process is completed, the process returns to step b2 and the normal communication process is performed again.

FIG. 9 is a flow chart for explaining the operation of the slave terminal device S in the first communication operation. This flowchart describes a case where the device operates as a slave terminal device in the interrupt communication process described above. Step c
At 1, it is determined whether communication from the serial data input terminal Sin0 has been received. When the communication is received, the process proceeds to step c2. At step c2, it is judged whether or not the interrupt communication from the serial data input terminal Sin1 is received. When the interrupt communication is received, the process proceeds to step c6 described later. If no interrupt communication is received, the process proceeds to step c3.

At step c3, it is judged whether or not an error has occurred. If an error has occurred, step c
Return to 1. If no error has occurred, the process proceeds to step c4 to execute the communication process. That is, the request data from the master terminal device is received, or the response data corresponding to the request data is transmitted. Request data is received using the serial data input terminal Sin0. At step c5, it is determined whether or not the communication process is completed. If not completed, the process returns to step c2 to execute the communication process. When the communication processing is completed, the processing is ended.

At step c6, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step c1. If no error has occurred, step c7
Then, the interrupt communication process is executed. That is, the request data from another slave terminal device is received, or the response data corresponding to the request data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin1. At step c8, it is determined whether or not the communication process is completed. If not completed, the process returns to step c6 to continue the interrupt communication process. When the communication process is completed, the process returns to step c1 to resume the normal communication process.

FIG. 10 is a flow chart for explaining another operation of the slave terminal device S in the first communication operation. This flowchart describes a case where a slave terminal device in which an interrupt process has occurred, that is, a slave terminal device that operates as a master terminal device in an interrupt communication process. In step d1,
It is determined whether or not the communication from the serial data input terminal Sin0 is received. If communication is received, step d
In step 2, it is determined whether the interrupt communication request from the main control unit 11 has been received. When the interrupt communication request is received, the process proceeds to step d6 described later. If the interrupt communication request has not been received, the process proceeds to step d3.

At step d3, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step d1, and if no error has occurred, step d4.
Then, the communication process is executed. That is, the request data from the master terminal device M is received, or the response data corresponding to the request data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin0. At step d5, it is determined whether the communication process is completed. If not completed, the process returns to step d2 to continue the communication process. When the communication processing is completed, the processing is ended.

At step d6, the communication controller 12 starts the interrupt communication based on the interrupt communication request from the main controller 11 described above. That is, the communication initial state for interrupt communication is set. In step d7, it is determined whether an error has occurred. If an error has occurred, the process returns to step d6 to redo the interrupt communication process. If no error has occurred, the process proceeds to step d8 to execute the interrupt communication process. That is, request data is transmitted or response data is received. The reception of the response data here is performed using the serial data input terminal Sin1. Step d9
Then, the interrupt communication process is continued. When the communication process is completed, the process proceeds to step d10, the received response data is delivered to the main control unit 11, and then the process returns to step d1 to restart the normal communication process.

FIG. 11 is a block diagram for explaining another embodiment of the present invention. In the terminal devices M and S used in the embodiment of the present invention, the control circuit 2 has an interrupt input terminal ASR0, and a signal applied to the serial data input terminal Sin1 is also supplied to the input terminal ASR0. Has been given. When the control circuit 2 determines that there is an interrupt at the input terminal ASR0, it interrupts the communication process being executed, stores the state at the time of interruption (parameters necessary for the process, etc.), and interrupts it. When the communication process is completed, the normal communication process is resumed from the suspended state.

FIG. 12 is a time chart showing a second communication process performed by the data communication apparatus according to another embodiment of the present invention. While the response data to the request data from the master terminal device M is being transmitted, the response data from, for example, the slave terminal device S2 is transmitted on the communication line K.
When the interrupt communication process from the slave terminal device S4 is interrupted while being sent to each terminal device, each terminal device stores the state at the time when the interrupt communication process interrupts the interrupt communication process. After the processing is completed, the normal communication processing is restarted from the interrupted state. That is, the slave terminal device S2 resumes data transmission after the interruption, and then the remaining terminal devices S3 and S4 sequentially send response data.

FIG. 13 is a flow chart for explaining the operation of the master terminal device M in the second communication operation. In step b21, it is determined whether the communication control unit 12 has received the communication request from the main control unit 11. When the communication request is received, the process proceeds to step b22 and the communication control unit 12
Communication is started. That is, the communication initial state is set. At step b23, it is determined whether or not the interrupt input terminal ASR0 has an interrupt. If there is an interrupt, the process proceeds to step b28 described below, and if there is no interrupt, the process proceeds to step b24.

At step b24, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step b22 and communication is retried. If no error has occurred, the process proceeds to step b25 to execute the communication process.
That is, request data is transmitted or response data is received. The reception of the response data here is performed using the serial data input terminal Sin0. At step b26,
It is determined whether the communication processing is completed. If not completed, the process proceeds to step b23 to continue the communication process. When the communication process is completed, the process proceeds to step b27, the received response data is delivered to the main control unit 11, and the process is completed.

At step b28, the normal communication process is interrupted and the input to the serial data input terminal Sin0 is invalidated. In step b29, it is determined whether an error has occurred. If an error has occurred, step b32
Then, the interrupted communication process is restored, and the process returns to step b24 described above. If no error has occurred, the process proceeds to step b30 to execute the interrupt communication process. That is, the request data is received or the response data is transmitted. The request data is received at the serial data input terminal Si.
n1 is used. At step b31, it is determined whether or not the communication process is completed. If not completed, the process proceeds to step b29 to continue the communication process. When the communication processing is completed, the process proceeds to step b32 and the above-mentioned step b
The communication processing interrupted in step 28 is restored, and the above-mentioned step b
Returning to 24, the normal communication process is restarted.

FIG. 14 is a flow chart for explaining the operation of the slave terminal device S in the second communication operation.
This flowchart describes a case where both the normal communication process and the interrupt communication process operate as a slave terminal device. At step c21, it is judged whether or not the communication from the serial data input terminal Sin0 is received. When the communication is received, the process proceeds to step c22, and it is determined whether the interrupt input terminal ASR0 has an interrupt. If there is an interrupt, the process proceeds to step c26 described below, and if there is no interrupt, the process proceeds to step c23.

At step c23, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step c21 and the normal communication process is performed again. If no error has occurred, the process proceeds to step c24 to execute the communication process. That is, the request data is received or the response data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin0. Step c2
At 5, it is determined whether the communication processing is completed. If not completed, the process proceeds to step c22 to continue the normal communication process. When the communication processing is completed, the processing is ended.

At step c26, the normal communication process is interrupted and the serial data input terminal Sin0 is made invalid. At step c27, it is judged whether or not an error has occurred. If an error has occurred, the process proceeds to step c30, the interrupted communication process is restored, and the above-described step c2 is performed.
Returning to step 3, the normal communication process is restarted. If no error has occurred, the process proceeds to step c28 to execute the interrupt communication process. That is, the request data is received or the response data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin1. In step c29, it is determined whether or not the communication process is completed. If not completed, the process proceeds to step c27 to continue the interrupt communication process. When the communication process is completed, the process proceeds to step c30, the interrupted communication process is restored, the process returns to step c23, and the normal communication process is restarted.

FIG. 15 is a flow chart for explaining another operation of the slave terminal device S in the second communication operation. This flowchart describes a case where the normal communication process operates as a slave terminal device and the interrupt communication process operates as a master terminal device. At step d21, it is judged whether or not the communication from the serial data input terminal Sin0 is received. When the communication is received, the process proceeds to step d22, and it is determined whether or not there is an interrupt communication request from the main control unit 11. If there is an interrupt communication request, the process proceeds to step d26 described later, and if there is no interrupt communication request, step d26.
Proceed to 23.

At step d23, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step d21 and the normal communication process is performed again. If no error has occurred, the process proceeds to step d24 to execute the communication process. That is, the request data is received or the response data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin0. Step d2
At 5, it is determined whether the communication processing is completed. If not completed, the process returns to step d22 to continue the normal communication process. When the communication processing is completed, the processing is ended.

At step d26, the normal communication process is interrupted and the data input terminal Sin0 is made invalid. Step d
At 27, the interrupt communication process is started. That is, the communication initial state for interrupt communication is set. Step d28
Then, determine whether an error has occurred. If an error has occurred, the process proceeds to step d32, the interrupted normal communication process is restored, and the process proceeds to step d23 to restart the normal communication process. If no error has occurred, the process proceeds to step d29 to execute the interrupt communication process. That is,
Send request data or receive response data. Reception of the response data here is performed by the serial data input terminal S
This is done using in1.

At step d30, it is determined whether or not the communication processing is completed. If the communication process is not completed, the process returns to step d28 to continue the interrupt communication process. When the communication processing is completed, the process proceeds to step d31, and the main control unit 1
The received response data is delivered to 1, and the process proceeds to step d32. Thereafter, similarly to the above, the interrupted normal communication process is restored, the process proceeds to step d23, and the normal communication process is restarted.

16, 17, and 18 are flowcharts for explaining still another embodiment of the present invention. In the third communication operation performed in still another embodiment of the present invention, the normal communication process is the serial data input terminal Si.
n0, only the first byte data of the interrupt communication process is performed using the serial data input terminal Sin1,
The subsequent data is characterized by using the serial data input terminal Sin0. As a result, even if it is necessary to execute the interrupt communication process that is prioritized during execution of the interrupt communication process, the communication process can be executed without any trouble.

FIG. 16 is a flow chart for explaining the operation of the master terminal device M in the third communication operation. In step b41, it is determined whether the communication control unit 12 has received the communication request from the main control unit 11. When the communication request is received, the process proceeds to step b42 and the communication control unit 12
Communication is started. That is, the communication initial state is set. At step b43, it is determined whether or not the interrupt input terminal ASR0 has an interrupt. If there is an interrupt, the process proceeds to step b48 described later, and if there is no interrupt, the process proceeds to step b44.

At step b44, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step b42 and communication is retried. If no error has occurred, the process proceeds to step b45 to execute the communication process.
That is, request data is transmitted or response data is received. The reception of the response data here is performed using the serial data input terminal Sin0. In step b46,
It is determined whether the communication processing is completed. If the communication process is not completed, the process returns to step b43 to continue the communication process. When the communication process is completed, the process proceeds to step b47, the received response data is delivered to the main control unit 11, and the process is completed.

At step b48, the normal communication process is interrupted and the serial data input terminal Sin0 is made invalid. In step b49, it is determined whether an error has occurred. If an error occurs, the process proceeds to step b55, the interrupted normal communication process is restored, and step b44
Then, the normal communication process is restarted. If no error has occurred, the process proceeds to step b50.

At step b50, it is judged whether or not the reception of the 1-byte data is completed. If not completed, the process proceeds to step b51, where serial data input terminal Si
After setting n1 and the serial data output terminal Sout1 to the use state, the process proceeds to step b53. When the reception of 1-byte data is completed, the process proceeds to step b52, and the serial data input terminal Sin0 and the serial data output terminal Sout0 are used, and the process proceeds to step b53. At step b53, interrupt communication processing is executed. That is, the request data is received or the response data is transmitted. Here, the response data is transmitted using the serial data output terminal Sout0, and the request data is received by using the serial data input terminal Sin1 for the first 1-byte data.
And the remaining byte data is received using the serial data input terminal Sin0.

At step b54, it is determined whether the communication is completed. If communication has not ended, step b
Proceed to 49 to continue the interrupt communication process. When the communication is completed, the process proceeds to step b55, the normal communication state interrupted at step b48 is restored, and the process proceeds to step b44 to restart the normal communication process.

FIG. 17 is a flow chart for explaining the operation of the slave terminal device S in the third communication operation.
This flowchart describes a case where both the normal communication process and the interrupt communication process operate as a slave terminal device. At step c41, it is judged whether or not the communication from the serial data input terminal Sin0 is received. When the communication is received, the process proceeds to step c42, and it is determined whether or not the interrupt input terminal ASR0 has an interrupt. If there is an interrupt, the process proceeds to step c46 described below, and if there is no interrupt, the process proceeds to step c43.

At step c43, it is judged whether or not an error has occurred. If an error has occurred, the process returns to step c41 and communication is performed again. If no error has occurred, the process proceeds to step c44 to execute normal communication processing. That is, the request data from the master terminal device is received, or the response data corresponding to the request data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin0. At step c45, it is determined whether the communication is completed. If not completed, the process returns to step c42 to continue the communication process. When the communication is completed, the processing is ended.

At step c46, the normal communication process is interrupted, and at step c47, it is judged whether or not an error has occurred. If an error has occurred, step c53
In step c43, the normal communication process is restored, and the process returns to step c43 to restart the normal communication process. If no error has occurred, the process proceeds to step c48.

At step c48, it is judged whether or not the reception of the data of 1 byte is completed. If not completed, in step c49, the serial data input terminal Sin1 and the serial data output terminal Sout1 are put into the use state, and the process proceeds to step c51. If the reception of 1-byte data has been completed, the serial data input terminal Sin0 and the serial data output terminal Sout0 are set to the use state in step c50, and the step c5
Proceed to 1.

At step c51, interrupt communication processing is executed. That is, the request data is received or the response data is transmitted. Here, the response data is transmitted using the serial data output terminal Sout0, and the request data is received for the first 1 byte by the serial data input terminal Si.
n1 and the remaining byte data is performed using the serial data input terminal Sin0.

At step c52, it is determined whether the communication is completed. If it has not ended, the process returns to step c47 to continue the interrupt communication process. When the communication is completed, the process proceeds to step c53, the interrupted normal communication process is restored, the process returns to step c43, and the normal communication process is restarted.

FIG. 18 is a flow chart for explaining another operation of the slave terminal device S in the third communication operation. This flowchart describes a case where the normal communication process operates as a slave terminal device and the interrupt communication process operates as a master terminal device. In step d41, it is determined whether communication from the serial data input terminal Sin0 has been received. If received, go to step d42,
It is determined whether or not an interrupt communication request from the main control unit 11 has been received. If there is an interrupt communication request, the process proceeds to step d46 described later, and if there is no interrupt communication request, step d4.
Proceed to 3. In step d43, it is determined whether an error has occurred. If an error has occurred, the process returns to step d41 and communication is retried. If no error has occurred, the process proceeds to step d44 to execute normal communication processing. That is, the request data is received or the response data is transmitted. The reception of the request data here is performed using the serial data input terminal Sin0.

At step d45, it is determined whether the communication is completed. If communication has not ended, step d
Returning to 42, the normal communication process is continued. When the communication is completed, the processing is ended.

At step d46, the normal communication process is interrupted, and at step d47, interrupt communication is started. That is, the communication initial state for interrupt communication is set. In step d48, it is determined whether an error has occurred. If an error has occurred, proceed to step d55,
The normal communication process is restored, the process returns to step d43, and the normal communication process is restarted. If no error has occurred, the process proceeds to step d49.

At step d49, it is judged whether or not the transmission of 1-byte data is completed. If not completed, in step d50, the serial data input terminal Sin1 and the serial data output terminal Sout1 are put into use, and the process proceeds to step d52. If the reception of one byte of data has been completed, the serial data input terminal Sin0 and the serial data output terminal Sout0 are set to the use state in step d51, and then step d5
Proceed to 2.

At step d52, the interrupt communication process, that is, the request data is received or the response data is transmitted. Here, the request data is transmitted using the serial data output terminal Sout1 for the first byte, the remaining byte data is transmitted using the serial data output terminal Sout0, and the response data is received through the serial data input terminal Sin0. Using.

At step d53, it is determined whether the communication is completed. If communication has not ended, step d
Returning to 48, the interrupt communication process is continued. When the communication is completed, the process proceeds to step d54, the received response data is delivered to the main control unit 11, and the process proceeds to step d55. Thereafter, similarly to the above, in step d55, the interrupted normal communication process is restored, the process returns to step d43, and the normal communication process is restarted.

FIG. 19 is a flow chart for explaining in detail the processing when detecting the occurrence of an error. At step e1, it is determined whether or not an overrun error has occurred. At step e2, it is judged whether or not a framing error has occurred. Further step e
At 3, it is determined whether the detection potential levels of the serial data input terminals Sin0 and Sin1 are equal. If the potentials are equal, it is normal, and if the potentials are not equal, it is determined that an error has occurred.

In this way, in step e3, the data (detection potential) of the serial data input terminals Sin0 and Sin1 are compared and checked, whereby the input terminal and the buffer in the control circuit 2 can be checked.

As described above, according to the embodiment of the present invention, when the interrupt communication process having a higher priority than the normal communication process is executed during the execution of the normal communication process, the normal communication process is executed. The second data that is different from the first data that is used when performing is performed. The third potential V3 forming the second data is the second potential V2 forming the first data.
If the first data and the second data overlap, the first data will be destroyed, but the second data will be destroyed even if part of it is destroyed. Can receive interrupt data without any effect. This greatly improves the reliability of data communication.

Even if the interrupt communication process with a higher priority is interrupted by switching the interrupt communication process to the first data and executing the interrupt data, the interrupt data with a higher priority is destroyed. You can send and receive without doing. This greatly improves the reliability of data communication.

Further, as described above, by switching the interrupt communication processing to the first data from the middle, the terminal device is
When you need to prepare a transmission circuit and a reception circuit for transmitting different types of data, and a circuit for transmitting and receiving multiple types of data according to high priority data. Compared with, the configuration related to data transmission and reception can be downsized, and further cost reduction can be realized.

[0072]

As described above, according to the present invention, it is possible to reliably transmit and receive high-priority interrupt data without destroying it, and the reliability of data communication is significantly improved.
Further, the interrupt communication process and the normal communication process can be smoothly performed, and the reliability of data communication is improved.

Further, according to the present invention, even when a plurality of interrupt data with a high priority are overlapped, the interrupt data with the highest priority is not destroyed and the interrupt data with a high priority is Data can be reliably transmitted and received, and reliability in data communication is significantly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a data communication device 1 which is a premise of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of terminal devices M and S.

FIG. 3 is an embodiment of the present invention, in which the terminal devices M and S
3 is a block diagram showing a specific configuration example of the communication circuit 10 of FIG.

FIG. 4 is a time chart showing a configuration example of message data transmitted and received by the data communication device 1.

FIG. 5 is a waveform diagram showing data used by the data communication device 1.

FIG. 6 is a flowchart illustrating an operation performed by the control circuit 2 when receiving data.

FIG. 7 is a time chart illustrating a first communication operation performed by the data communication device 1.

FIG. 8 is a flowchart illustrating an operation executed by the master terminal device M in the first communication operation.

FIG. 9 is a flowchart illustrating an operation performed by the slave terminal device S in the first communication operation.

FIG. 10 is a flowchart illustrating another operation performed by the slave terminal device S in the first communication operation.

FIG. 11 is a block diagram for explaining another embodiment of the present invention.

FIG. 12 is a time chart illustrating a second communication operation performed by the data communication device.

FIG. 13 is a flowchart illustrating an operation performed by master terminal device M in a second communication operation.

FIG. 14 is a flowchart illustrating an operation performed by the slave terminal device S in a second communication operation.

FIG. 15 is a flowchart illustrating another operation performed by the slave terminal device S in the second communication operation.

FIG. 16 is a flowchart illustrating an operation performed by master terminal device M in a third communication operation.

FIG. 17 is a flowchart illustrating an operation performed by the slave terminal device S in a third communication operation.

FIG. 18 is a flowchart illustrating an operation performed by the slave terminal device S in a third communication operation.

FIG. 19 is a flowchart illustrating in detail a process when detecting whether or not an error has occurred.

[Explanation of symbols]

 1 data communication device 2 control circuit 3 connection terminal 4 data transmission circuit 5 data reception circuit 6,7 switch 8,9 comparator 10 communication circuit 11 main control unit 12 communication control unit K communication line M master terminal device S (S1 to Sn) Slave terminal device R1 to R5 resistance B power supply potential Sin0, Sin1 serial data input terminal Sout0, Sout1 serial data output terminal ASR0 interrupt input terminal P1, P2 connection point V1 first potential V2 second potential V3 third potential Vth1 First reference potential Vth2 Second reference potential

Claims (5)

[Claims] 1. A main terminal device connecting a plurality of terminal devices with one communication line in which a predetermined first potential is in a standby state, and a main terminal device selected from the plurality of terminal devices requests another terminal device. In a data communication device that transmits data and another terminal device transmits response data to the request data in order according to a predetermined priority order that determines the order of data transmission to the main terminal device, each terminal device is a communication device. The potential of the line is switched to the first potential and a predetermined second potential lower than the first potential to create and transmit the first data, and the potential of the communication line Second data transmitting means for switching between the first potential and a predetermined third potential lower than the second potential to generate and transmit the second data, and detecting the potential of the communication line. First and second Data reception means for receiving data, and when performing a normal communication process consisting of request data transmission by the main terminal device and response data transmission by another terminal device, the first data The second data is used when performing an interrupt communication process for transmitting interrupt data prior to the normal communication process during normal communication process. . 2. Each terminal device interrupts the normal communication process when the interrupt communication process interrupts during the normal communication process,
The data communication device according to claim 1, wherein the main terminal device retransmits the requested data in the interrupted normal communication process after the interrupt communication process is completed. 3. Each terminal device interrupts the normal communication process when the interrupt communication process interrupts during the normal communication process,
The data communication apparatus according to claim 2, wherein the interrupted normal communication process is restarted after the interrupt communication process is completed. 4. The terminal device switches to the first data and performs the interrupt communication process after the transmission and reception of the first at least 1-bit data of the interrupt communication process is completed. The data communication device according to claim 1. 5. The data receiving means includes first potential detecting means for detecting whether the potential of the communication line is higher or lower than a first reference potential selected between the first and second potentials. A second potential detecting means for detecting whether the potential of the communication line is higher or lower than a second reference potential selected between the second and third potentials, each terminal device comprising: 4. The data communication device according to claim 3, wherein it is determined that an error has occurred when the detection results of the first and second potential detection means do not match.