JPH11239197A - Communication controller and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an equipment capable of transferring data without being conscious of the bus state of duplex buses by connecting a master station and a slave station by the duplex buses, simultaneously sending out the command frames of the same contents from the master station to the duplex buses, performing a self matching inspection to the two received contents and performing the next processing corresponding to an inspected result. SOLUTION: In the master station 1, a processor 11 is in charge of the control of the entire master station 1. A sequencer 12 is connected through bus interfaces 131 and 132 to buses 21 and 22. A communication means 121 inside the sequencer 12 simultaneously sends out the command frames of the same contents to the buses 21 and 22 and an inspection bit is added to the command frame. The sent-out command frames are passed through the buses 21 and 22, repeaters 31 and 32 and the buses 41 and 42 and arrive at the slave station 5. In the slave station 5, the communication means 521 receives the command frames.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device and a communication control method for connecting a master station and a slave station by a duplex bus and controlling communication between these stations.

[0002]

2. Description of the Related Art In communication between a master station and a slave station, in order to increase the reliability of communication,
Buses connecting stations may be duplicated.
In such a duplicated bus system, when both buses are normal, communication is performed using the duplicated buses alternately. When one of the buses fails, communication is continued using a normal bus, and communication for checking whether or not the failed bus has been recovered is performed.

[0003]

However, in the above-described conventional example, the processor on the master station side does not communicate between the master and slave unless the bus state of the duplex bus is considered. That is, it is necessary to be aware of which of the redundant buses is the working side and which is the standby side. When one of the buses fails, control must be performed to switch the bus to be used.

Inspection of the integrity of transfer data has been performed by adding a check bit to the transfer data. However, the inspection using the inspection bits can check the soundness of the data on the bus, but cannot check the soundness of data other than the bus, for example, the parts such as the bus interface, the bridge, and the repeater.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and simultaneously transmits command frames of the same content to a duplex bus regardless of the status of the duplex bus.
The processor on the master station performs data transmission between the master and slave units without having to be aware of the duplex bus status by determining whether communication is correct based on whether the received contents match on the receiving side. It is another object of the present invention to provide a communication control device and a communication control method capable of checking the soundness of data in parts other than the bus.

[0006]

SUMMARY OF THE INVENTION The present invention provides a communication control device and a communication control method having the following configurations.

(1) In a communication control device for connecting a master station and a slave station via a duplex bus and controlling communication between the stations, a processor for controlling the entire master station and a master bus for the duplex bus are the same. A command frame of the content is transmitted at the same time, a first communication means for adding a check bit to the command frame, and a check bit is used for the two received contents received by the slave station via the duplex bus. A communication control device, comprising: first communication procedure control means for performing a self-alignment check, checking whether two received contents match, and performing the next processing according to the check result. When a command frame determined to be normal by the check bit is received from the buses on both sides, and the two received contents match, the operation is performed according to the command contents, and a normal end response having the same contents is returned to both buses. When a command frame determined to be normal by the check bit is received from one of the buses, the operation is performed in accordance with the content of the command, and a normal end response is returned only to the bus that has received the command frame determined to be normal by the check bit. If a command frame determined to be normal by the check bit is received from both buses, and the two received contents do not match, the command contents are ignored and an abnormal end response having the same contents is returned to both buses. . If a command frame determined to be normal by the check bit is not received from either bus,
No response is returned to either bus.

(2) A response frame is transmitted from the slave station to the duplex bus, a second communication means for adding a check bit to the response frame, and a response from the slave station is monitored. (2) The communication control device according to (1), further comprising second communication procedure control means for performing the processing of (1). If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents are a normal end response, the processor notifies the processor of the normal end of access. If the response frame determined to be normal by the check bit is received from the one-side bus and the received content is a normal end response, the normal end of access is notified to the processor. If the response frame determined to be normal by the check bit is received from both buses, and if the two received contents do not match, the response frame determined to be normal by the check bit is received from both buses, and If the two received contents are an abnormal termination response that matches, or a response frame determined to be normal by the check bit is received from one bus, and
If the received content is an abnormal termination response, the processor is notified of the abnormal termination of the access. If a response frame determined to be normal by the check bit is not received from either bus, an abnormal termination of access is notified to the processor.

(3) The communication control device according to (2), further comprising a notifying means for notifying the processor which of the above-mentioned cases the access to the slave station is completed.

(4) In a communication control method for connecting a master station and a slave station via a duplex bus and controlling communication between these stations, a command frame having the same content is simultaneously transmitted from the master station to the duplex bus. A check bit is added to the command frame, and the slave station receives the command frame sent via the duplex bus, and uses the check bits to check the received contents of the two received contents for self-alignment. A communication control method comprising: performing a check, checking whether two received contents match, and performing the following processing according to the check result. When a command frame determined to be normal by the check bit is received from the buses on both sides, and the two received contents match, the operation is performed according to the command contents, and a normal end response having the same contents is returned to both buses. When a command frame determined to be normal by the check bit is received from one of the buses, the operation is performed in accordance with the content of the command, and a normal end response is returned only to the bus that has received the command frame determined to be normal by the check bit. If a command frame determined to be normal by the check bit is received from both buses, and the two received contents do not match, the command contents are ignored and an abnormal end response having the same contents is returned to both buses. . If a command frame determined to be normal by the check bit is not received from either bus,
No response is returned to either bus.

(5) A response frame is sent from the slave station to the duplex bus, and a check bit is added to the response frame. The master station monitors the response from the slave station, and responds to the monitoring result according to the monitoring result. (4) The communication control method according to (4), wherein If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents are a normal end response, the normal end of access is notified to the processor of the master station. . When a response frame determined to be normal by the check bit is received from one bus and the received content is a normal end response, the processor notifies the processor of normal end of access. If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents do not match, a response frame determined to be normal by the check bit is received from both buses, and If the two received contents are an abnormal termination response that matches, or a response frame determined to be normal by the check bit is received from one bus, and
If the received content is an abnormal termination response, the processor is notified of the abnormal termination of the access. If a response frame determined to be normal by the check bit is not received from either bus, an abnormal termination of access is notified to the processor.

(6) The communication control method according to (5), wherein the processor is notified of which of the above cases the access to the slave station is completed and ended.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention. In FIG. 1, duplex buses 21 and 22 are connected to the master station 1, and the buses 21 and 22 are connected to the relay device 3.
The buses 41 and 42 are connected to the duplicated buses 41 and 42 via the buses 1 and 32, and the buses 41 and 42 are connected to the slave station 5. The relay devices 31 and 32 are, for example, bridges and repeaters. Note that the relay devices 31 and 32 need not be provided. In this case, buses 21 and 22 and buses 41 and 42
Will be the same bus.

In the master station 1, the processor 11
Controls the master station 1 as a whole. The sequencer 12 is connected to buses 21 and 22 via bus interfaces 131 and 132. The sequencer 12 includes a communication unit 121, a communication procedure control unit 122, and a notification unit 1.
23 are provided, and these operations will be described later.

In the slave station 5, a slave device 51
Is a device that operates under the command and control of the master station 1, which is a memory in the example of FIG. The sequencer 52 is connected to the buses 41 and 42 via bus interfaces 531 and 532.
It is connected to the. Communication means 521 is provided in the sequencer 52.
The communication procedure control means 522 is provided, and these operations will be described later.

The operation of the communication control device shown in FIG. 1 will be described. The communication means 121 in the sequencer 12 simultaneously sends command frames having the same contents to the buses 21 and 22. Check bits are added to this command frame. The transmitted command frame is transmitted to the buses 21 and 22 and the relay device 3.
1 and 32, and reach the slave station 5 via the buses 41 and 42.

In the slave station 5, the communication means 5
21 receives the command frame. The communication procedure control means 522 processes the received command frame.

FIG. 2 is an explanatory diagram of the operation of the communication procedure control means 522. The communication procedure control means 522 includes the buses 41 and 42
The self-alignment is checked using the check bits for the two reception contents received by the slave station via the STA, and the two reception contents are checked whether they match,
The following processing is performed according to the inspection result. Inspection of whether or not there is an error in the received content is performed by, for example, CRC (Cyclic Redun
(dancy check).

When a command frame judged to be normal by the check bit is received from the buses on both sides, and when the two received contents match, the operation is performed in accordance with the command contents, and a normal end response having the same contents is sent to both buses. return it. When a command frame determined to be normal by the check bit is received from one of the buses, the operation is performed in accordance with the content of the command, and a normal end response is returned only to the bus that has received the command frame determined to be normal by the check bit. If a command frame determined to be normal by the check bit is received from both buses, and the two received contents do not match, the command contents are ignored and an abnormal end response having the same contents is returned to both buses. . If a command frame determined to be normal by the check bit is not received from either bus,
No response is returned to either bus.

Here, the reception of the command frame determined to be normal by the check bit indicates that the command frame is received and the check result by the check bit is normal.

On the other hand, the communication means 521 sends the response frame of the communication procedure control means 522 to the buses 41 and 42. A check bit is added to this response frame. On the master station 1 side, the communication procedure control means 1
Reference numeral 22 monitors a response from the slave station 5. FIG. 3 is an explanatory diagram of the operation of the communication procedure control means 122. The communication procedure control unit 122 monitors the response from the slave station 5 and performs the following processing according to the monitoring result.

A response frame determined to be normal by the check bit is received from both buses, and
If the two received contents match, the processor 11 notifies the processor 11 of the normal end of the access. If a response frame determined to be normal by the check bit is received from one bus and the received content is a normal end response, the processor 11 is notified of the normal end of access to the processor 11. If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents do not match, a response frame determined to be normal by the check bit is received from both buses, and If the two received contents are an abnormal termination response that matches, or a response frame determined to be normal by the check bit is received from one bus, and
If the received content is an abnormal end response, the processor 11 is notified of the abnormal end of the access to the processor 11. When the response frame determined to be normal by the check bit is not received from either bus, the processor 11 is notified of the abnormal termination of the access to the processor 11.

The notifying means 123 notifies the processor 11 of which of the above-mentioned conditions (1) to (5) has been completed.

The communication procedure control means 122 sets a status flag indicating [the state of the bus 41, the state of the bus 42, and the consistency of the received contents]. The processor 11 checks the status flag when diagnosing the state of the bus.

[0025]

As described above, according to the present invention, the following effects can be obtained.

According to the first to fourth aspects, the following effects can be obtained. Data exchange and control of the redundant bus can be separated. As a result, the processor on the master station side can exchange data between the master and slave during normal access without being aware of the bus state of the duplex bus. Both the master station and the slave station receive data from both buses, and if the check result by the check bit is normal for the two received contents but the two received contents do not match, it is determined to be abnormal. . As a result, the soundness of the received content can be checked even for a portion where an error cannot be detected by the check bit, for example, a bus interface, a bridge, a repeater, and the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master station 5 Slave station 11 Processor 21, 22, 41, 42 Bus 121, 521 Communication means 123 Notification means 122, 522 Communication procedure control means

Claims (6)

[Claims] 1. A communication control device for connecting a master station and a slave station via a duplex bus and controlling communication between the stations, wherein a processor for controlling the entire master station and the same content from the master station to the duplex bus. And the first communication means for adding a check bit to the command frame, and using the check bit for the two received contents received by the slave station via the duplex bus. A communication control device, comprising: first communication procedure control means for performing a matching check, checking whether two received contents match, and performing the next processing according to the check result. When a command frame determined to be normal by the check bit is received from the buses on both sides, and the two received contents match, the operation is performed according to the command contents, and a normal end response having the same contents is returned to both buses. When a command frame determined to be normal by the check bit is received from one of the buses, the operation is performed in accordance with the content of the command, and a normal end response is returned only to the bus that has received the command frame determined to be normal by the check bit. If a command frame determined to be normal by the check bit is received from both buses, and the two received contents do not match, the command contents are ignored and an abnormal end response having the same contents is returned to both buses. . If a command frame determined to be normal by the check bit is not received from either bus,
No response is returned to either bus. 2. A response frame is transmitted from the slave station to the duplex bus, a second communication means for adding a check bit to the response frame, and a response from the slave station is monitored. The communication control device according to claim 1, further comprising a second communication procedure control unit that performs a process. If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents are a normal end response, the processor notifies the processor of the normal end of access. If the response frame determined to be normal by the check bit is received from the one-side bus and the received content is a normal end response, the normal end of access is notified to the processor. If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents do not match, a response frame determined to be normal by the check bit is received from both buses, and If the two received contents are an abnormal termination response that matches, or a response frame determined to be normal by the check bit is received from one bus, and
If the received content is an abnormal termination response, the processor is notified of the abnormal termination of the access. If a response frame determined to be normal by the check bit is not received from either bus, an abnormal termination of access is notified to the processor. 3. The communication control device according to claim 2, further comprising: a notifying unit that notifies the processor which of the above cases the access to the slave station has been completed in one of the above cases. 4. A communication control method for connecting a master station and a slave station with a duplex bus and controlling communication between these stations, wherein a command frame having the same content is simultaneously transmitted from the master station to the duplex bus, and A check bit is added to the frame, and the slave station receives the command frame transmitted via the duplex bus, and performs a self-alignment check on the two received contents using the check bit. And checking whether the two received contents match, and performing the following processing according to the check result. When a command frame determined to be normal by the check bit is received from the buses on both sides, and the two received contents match, the operation is performed according to the command contents, and a normal end response having the same contents is returned to both buses. When a command frame determined to be normal by the check bit is received from one of the buses, the operation is performed in accordance with the content of the command, and a normal end response is returned only to the bus that has received the command frame determined to be normal by the check bit. If a command frame determined to be normal by the check bit is received from both buses, and the two received contents do not match, the command contents are ignored and an abnormal end response having the same contents is returned to both buses. . If a command frame determined to be normal by the check bit is not received from either bus,
No response is returned to either bus. 5. A slave station sends a response frame to a duplex bus, a check bit is added to the response frame, and the master station monitors a response from the slave station.
The communication control method according to claim 4, wherein the following processing is performed according to the monitoring result. If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents are a normal end response, the normal end of access is notified to the processor of the master station. . When a response frame determined to be normal by the check bit is received from one bus and the received content is a normal end response, the processor notifies the processor of normal end of access. If a response frame determined to be normal by the check bit is received from both buses, and if the two received contents do not match, a response frame determined to be normal by the check bit is received from both buses, and If the two received contents are an abnormal termination response that matches, or a response frame determined to be normal by the check bit is received from one bus, and
If the received content is an abnormal termination response, the processor is notified of the abnormal termination of the access. If a response frame determined to be normal by the check bit is not received from either bus, an abnormal termination of access is notified to the processor. 6. The communication control method according to claim 5, wherein the processor is notified of which of the above cases the access to the slave station has ended and has been completed.