JPH10200602A - Master / slave communication system - Google Patents

Abstract

(57) [Problem] To provide a master / slave communication system with improved reliability and communication speed. A modem that operates under the command of a microprocessor, a communication control unit that controls the operations of the microprocessor and the modem, and a bus that measures the time from the start to the end of the communication and forcibly terminates the communication when a timeout occurs. In a master / slave communication system including a master communication device having a timer and a plurality of slave communication devices, a timeout signal from the bus timer is latched and notified to the communication control unit at the start of communication, and communication is started. A master communication device having a failure information storage unit that latches and stores a time-out signal to the communication control unit and the microprocessor when the bus timer times out after being started; It is a slave communication system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master / communication device having a master communication device and a plurality of slave communication devices.
In a slave communication system, the master / master has improved reliability and communication speed when a communication failure occurs.
The present invention relates to a slave communication system.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of the structure of a conventional example generally used in the prior art. In the figure, 1 is a master communication device, and 2 is a plurality of slave communication devices. Reference numeral 3 denotes a microprocessor (MPU) in the master communication device 1. Reference numeral 4 denotes a modem operated by a command of a microprocessor (MPU).

[0005] Reference numeral 5 denotes a communication control unit for controlling operations of the microprocessor (MPU) 3 and the modem 4. 6 is
The communication control unit 5 and the microprocessor (MPU) 3 measure the time from the start to the end of the communication and
And a bus timer for notifying the user.

In the above configuration, the master communication device 1
When performing communication with the slave communication device 2, since the response time of the slave communication device 2 is slow, it is necessary to perform the following control.

When the microprocessor (MPU) 3 in the master communication device 1 executes a communication activation command for the slave communication device 2, the communication control unit 5 sets WAITX = L.
To enable the modem 4 and instruct the microprocessor (MPU) 3 to wait in the current state. While WAITX = L, the modem 4 communicates with the slave communication device 2 and the microprocessor (MP
U) 3 keeps waiting in its current state.

When the communication is completed, the communication control unit 5
It outputs ITX = H, the modem 4 stops, and the microprocessor (MPU) 3 executes the next instruction. In performing this control, conventionally, the bus timer 6 is widely used to detect a failure between the master communication device 1 and the slave communication device 2.

The bus timer 6 measures the time from the start to the end of the communication, and when the time reaches a certain specified time or more (time-out), notifies the communication control unit 5 and the microprocessor (MPU) 3 of the communication, and communicates. The control unit 5 forcibly terminates the communication. Therefore, when one of the slave communication devices 2 fails, the master communication device 1 can be prevented from being unable to operate.

[0008]

In such a device, when the master communication device 1 communicates with the slave communication device 2 continuously for a specified number of times, one of the slave communication devices 2 In case of failure and communication failure,
The bus timer 6 in the master communication device 1 times out, and the corresponding communication is forcibly terminated.

However, in such an apparatus,
If there is no special means, the communication is repeatedly started with respect to the failed slave communication device 2 after that, and a timeout is waited. Since the time-out period is set to be longer than the time required for communication in the normal state, it takes a very long time, and it may be impossible to perform communication with all slave communication devices 2 within the specified time. there were. Further, there is a possibility that the communication is started many times with respect to the failed slave communication device 2 and erroneous data is obtained.

In order to avoid this, the microprocessor (MPU) 3 checks the timeout of the bus timer 6 each time communication is performed, and if a timeout occurs, the microprocessor (MPU) 3 controls the firmware so as not to start the next communication. I needed to.

For example, as shown in the flowchart of FIG.
Communication had to be controlled. In FIG. 2, when the microprocessor (MPU) 3 executes the communication start command,
The communication control unit 5 outputs WAITX = L, the modem 4 starts communication, and the microprocessor (MPU) 3
Keeps waiting until WAITX = H.

When the communication is completed normally, the communication control section 5 outputs WAITX = H. For example, when the slave communication device 2 fails and communication is disabled, the timeout of the bus timer 6 is notified to the communication control unit 5 and the microprocessor (MPU) 3, and the communication control unit 5
TX = H is output.

Next, the modem 4 stops, and the microprocessor (MPU) 3 checks the timeout of the bus timer 6. If the timeout has occurred, the communication is abnormally terminated, and thereafter, abnormal processing is performed.

If the timeout has not occurred, the communication is repeated until the communication with the slave communication device 2 is performed a specified number of times. In such control by firmware, it is necessary to check the timeout of the bus timer 6 every time communication is performed, so that the communication speed is reduced.

The present invention solves this problem. An object of the present invention is to provide a master / slave communication system capable of improving reliability and communication speed.

[0016]

In order to achieve the above object, the present invention provides a modem operated by a command of a microprocessor, a communication control unit for controlling the operation of the microprocessor and the modem, a communication start and a communication end. In a master / slave communication system including a master communication device having a bus timer for counting the time until the communication is timed out and forcibly terminating the communication when the timeout occurs, a time-out signal from the bus timer is transmitted. Failure information for latching and notifying the communication control unit at the start of communication and for latching and notifying the communication control unit and the microprocessor of a timeout signal when the bus timer times out after the communication is started. A master comprising a master communication device having a storage unit / Is obtained by constituting the slave communication system.

[0017]

In the above configuration, the microprocessor (M
PU) executes the communication start command, the communication control unit receives the output of the failure information storage unit, and if no timeout has occurred before, outputs WAITX = L so as to start communication, and the modem performs communication. And the microprocessor (MPU) keeps waiting until WAITX = H. For example, if the slave communication device breaks down and there is a timeout, the communication control unit does not start communication, and
Keep AITX = H.

Next, when the communication is normally completed, the communication control section outputs WAITX = H, the modem is stopped, and the microprocessor (MPU) can execute the next instruction.

If the bus timer times out after the communication is started, the failure information storage unit latches and stores the time out, and the communication control unit and the microprocessor (M
PU). The communication control unit is WAITX
= H is output, and the communication is forcibly terminated.

The above operation is repeated until the communication with the slave communication device reaches a specified number. As described above, the microprocessor (MPU) executes the next communication start instruction, but as long as the failure information storage unit has the latch storage, the communication control unit does not start communication with the slave communication device, and the microprocessor (MPU) No extra wait time occurs. Hereinafter, a detailed description will be given based on embodiments.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part of an embodiment of the present invention, FIG. 2 is a detailed view of a specific main part of FIG. 1, and FIG. 3 is an explanatory view of an operation of FIG. In the figure, the configuration of the same symbol as FIG. 4 represents the same function. Hereinafter, only differences from FIG. 4 will be described.

In the figure, reference numeral 11 denotes a master communication device 1
And latches and stores the timeout signal from the bus timer 6 to notify the communication control unit 5 at the start of communication, and latches and stores when the bus timer 6 times out after the communication is started. , A failure information storage unit that notifies a timeout signal to the communication control unit 5 and the microprocessor (MPU).

In the above configuration, when the microprocessor (MPU) 3 executes the communication start command, the communication control unit 5 receives the output of the failure information storage unit 11 and starts communication if there is no timeout before. WA
ITX = L is output, the modem 4 starts communication, and the microprocessor (MPU) 3 sends the WAITX =
Keep waiting until it becomes H. For example, slave communication device 2
Has failed and a timeout has occurred, the communication control unit 5
Does not start communication and keeps WAITX = H.

Next, when the communication is normally completed, the communication control unit 5 outputs WAITX = H, the modem 4 stops, and the microprocessor (MPU) 3 can execute the next instruction. .

If the bus timer 6 times out after the communication is started, the failure information storage unit 11 latches and stores the time out, and notifies the communication control unit 5 and the microprocessor (MPU) 3 of the time out. Communication control unit 5
Outputs WAITX = H and forcibly terminates the communication.

The above operation is repeated until the communication with the slave communication device 2 reaches a specified number. As described above, the microprocessor (MPU) executes the next communication activation instruction. However, as long as the failure information storage unit 11 stores the latch, the communication control unit 5 does not start the communication with the slave communication device 2 and the microprocessor (MPU) starts the communication. No extra wait time of the processor (MPU) 3 occurs.

In the conventional example shown in FIG. 4, it is necessary to check the failure information a predetermined number of times. However, according to the present invention, the check may be performed once at the end of the communication.

When the microprocessor (MPU) 3 instructs the failure information storage unit 11 to clear the latch storage, the timeout latch storage is cleared.

In short, the present invention relates to a communication device comprising a master communication device 1 and a plurality of slave communication devices 2,
In consideration of the operation at the time of failure between the master communication device 1 and the slave communication device 2, a failure information storage unit 11 for timeout of the bus timer 6 is provided, and communication control for the slave communication device 2 is performed by hardware based on the failure storage information. It is something to do.

As a result, (1) when a failure occurs in the slave communication device 2 and once the failure is detected by the timeout of the bus timer 6, the communication with the failed slave communication device 2 is repeatedly executed, and the timeout is waited. As a result, a master / slave communication system that does not degrade performance is obtained.

(2) The failed slave communication device 2
In contrast, a master / slave communication system with improved reliability can be obtained in which the risk of acquiring communication data by starting communication many times is reduced.

(3) Conventionally, such communication control can be realized by a firmware of the microprocessor (MPU) 3, but the present invention provides a microprocessor (MPU)
3 can be performed without relying on the firmware, and a master / slave communication system capable of increasing the communication speed can be obtained.

(4) In the prior art, the check of the fault information had to be performed a prescribed number of times. However, according to the present invention,
This has the advantage that it only needs to be performed once at the end of the communication.

[0034]

As described in detail above, according to the present invention, (1) when a failure occurs in a slave communication device, if a failure is detected by timeout of a bus timer, communication with the failed slave communication device is performed. Is repeatedly executed, and a timeout is not waited, so that a master / slave communication system which does not degrade the performance is obtained.

(2) A master / slave communication system with improved reliability can be obtained in which the communication with the failed slave communication device is started many times and the risk of acquiring erroneous data is reduced.

(3) Conventionally, such communication control can be realized by a firmware of a microprocessor (MPU), but the present invention makes it possible to perform the communication control without relying on a firmware of a microprocessor (MPU). Things,
A master that can increase the communication speed
A slave communication system is obtained.

(4) In the prior art, the check of the failure information had to be performed a prescribed number of times. However, according to the present invention,
This has the advantage that it only needs to be performed once at the end of the communication.

Therefore, according to the present invention, a master / slave communication system with improved reliability and communication speed can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a detailed explanatory view of a main part of FIG. 1;

FIG. 3 is a flowchart illustrating the operation of FIG. 1;

FIG. 4 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

FIG. 5 is a flowchart illustrating the operation of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master communication device 2 Slave communication device 3 Microprocessor (MPU) 4 Modem 5 Communication control part 6 Bus timer 11 Failure information storage part

Claims (1)

[Claims] 1. A modem which operates under the command of a microprocessor, a communication control unit which controls the operation of the microprocessor and the modem, and a time from the start to the end of the communication is measured and the communication is forcibly terminated when a timeout occurs. In a master / slave communication system including a master communication device having a bus timer and a plurality of slave communication devices, a timeout signal from the bus timer is latched and notified to the communication control unit at the start of communication, and communication is performed. A master communication device having a failure information storage unit that latches and stores a time-out signal to the communication control unit and the microprocessor when the bus timer times out after the start of the operation. / Slave communication system.