JPH01149111A - Communication method between programmable controller and host cpu - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication method for mutually exchanging data between a host CPU and a plurality of programmable controllers (hereinafter referred to as PCs).

[Conventional technology]

Conventionally, the communication procedure between a PC and a host CPU is based on commands,
A communication method with half-duplex response was used.

The operation of the PC and the host CPU is as follows (see Figure 3).When the host CPU becomes ready for communication, it issues the command FCMD.
Create and send command CMD to the PC. When the host CPU completes sending the command to the PC, it enters a state in which it waits for a response R3P from the PC. When the PC receives the command CMD from the higher CPU, it processes the command CMD, creates a response R3P, and sends it to the higher CPU. When the PC completes sending the response to the upper CPU, it enters a command waiting state. Upper CPU is PC
When the response RSP is received from the server and processed (displayed, etc.), it becomes communicable.

[Problem that the invention seeks to solve]

In the conventional communication method described above, the host CPU sends a command to the PC and then waits until a response is returned from the PC. If it is not completed, it takes a long time for the PC to send a response, it takes a long time for the response to return to the upper CPII, and the upper CPU
The disadvantage is that the waiting time in communication processing increases and the efficiency of communication processing decreases. This problem becomes particularly noticeable when a plurality of PCs are connected to a host CPU as slaves.

[Means for solving problems]

In the communication method between the programmable controller and the host CPU of the present invention, when the PC receives a command from the host CPU, the PC returns a reception confirmation response to the host CPU before processing the command, and then a polling command is sent from the host CPU. If the command processing is completed, the PC returns the original response to the upper CPU.

[Effect]

Therefore, while the PC is processing a command, the host CPU can communicate with other PCs without waiting for a response, and can improve the efficiency of communication with a plurality of PC slaves.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the programmable controller of the present invention and the upper C
FIG. 2 is a sequence diagram of an embodiment of a communication method between PUs, and is a system configuration diagram consisting of a host CPU and a PC.

The upper CPUI creates a command CMD and sends it to the PC2. When the host CPUI completes sending the command to the PC2, it enters a state where it waits for a response R3P from the PCZ. When the receiving unit 3 receives the command CMD from the upper cptri, the PC 2 analyzes the command CM in the command analyzing unit 4.
D is analyzed, the response creation unit 6 creates an "ACK" response, and before the command CMD is processed by the processing unit 5, the response creation unit 7 sends an "ACK" response to the upper CPUI.
The upper CPUI returns an “ACK” response.
When received, communication becomes possible. PC2 is ACK”
After returning the response, the processing unit 5 starts processing the received command CMD. The upper CPUI requests “P” to request a response RSP to the original command FCMD.
OLL" = +ff is created and sent to PC2.

When the receiving section 3 of the PC 2 receives the "POLL" command, the response generating section 6 adds the original response RSP to the response and sends it back to the higher-level CPUI from the transmitting section 7. Upon receiving the response R3P, the upper CPU performs processing (display, etc.) on the response R3P,
Return to communicable state.

〔Effect of the invention〕

As explained above, the present invention allows the PC to send a confirmation response back to the upper CPU before sending the original response,
After that, when a polling command is sent from the upper CPU, by sending the original response, the upper CPU
Since the PU is in a communicable state while the PC is processing commands, it can communicate with other PC slaves, which has the effect of increasing the efficiency of communication with multiple PC slaves.

[Brief explanation of the drawing]

FIG. 1 is a sequence diagram showing an embodiment of the communication method between a PC and a host CPU of the present invention, FIG. 2 is a system configuration diagram of a PC and a host CPU, and FIG. 3 is a sequence diagram showing a conventional method. DESCRIPTION OF SYMBOLS 1... Upper CPU, 2... PCl3... Receiving section, 4... Command analysis section, 5... Processing section, 6... Response creation section, 7... Transmission section. Patent applicant Yaskawa Electric Co., Ltd. Agent
Patent Attorney Tadaaki Wakabayashi CPUI PC2 No. 1
Cause

Claims (1)

[Claims] When the programmable controller receives a command from the host CPU, it returns a reception confirmation response to the host CPU before processing the command, and then when the host CPU sends a polling command, the programmable controller returns the A communication method between a programmable controller and a host CPU that returns a response to the host CPU.