Communication method for programmable logic controller and extension module

An expansion module and programming logic technology, applied in the field of communication between programmable logic controllers and expansion modules, can solve the problems of poor anti-interference ability, inflexible use, low efficiency, etc., achieve strong anti-interference ability, improve real-time performance, The effect of enhancing reliability

Inactive Publication Date: 2009-12-02
SHANGHAI ELECTRICAL APPLIANCES RES INSTGROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method of selecting a group of address lines to transmit addresses is inflexible in hardware design. The maximum number of address lines determines the maximum number of expansion modules. Different programmable logic controller PLC host models have different numbers of address lines. The number of hard-connected cables may be different, and the cables connected to the side are not universal; and this method is essentially time-sharing transmission of addresses, commands and data. The address lines are parallel and the anti-interference ability is poor, so a group of addresses is selected. There are also major disadvantages of the line method
In addition, it is not flexible to use the method of setting the address by dialing

Method used

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  • Communication method for programmable logic controller and extension module
  • Communication method for programmable logic controller and extension module
  • Communication method for programmable logic controller and extension module

Examples

Experimental program
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Embodiment

[0026] In the communication method between the programmable logic controller and the expansion module of the present invention, the programmable logic controller PLC mainframe 1 and the expansion module 2 are connected to each other through a serial communication line using a side-by-side connection mode, and the expansion module 2 is connected to each other through communication The protocol state machine controller 21 identifies the aperiodic state data frame sent by the programmable logic controller PLC host 1, and sends a notification to the I / O refresh state machine controller 22 to request the I / O refresh state machine controller 22 to respond Received state data frame; the expansion module 2 recognizes the I / O refresh data frame sent by the programmable logic controller PLC host 1 through the I / O refresh state machine controller 22, and automatically responds to read and write data.

[0027] Such as figure 1 Shown, according to the PLC system structure diagram that the ...

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Abstract

The invention provides a communication method for a programmable logic controller and an extension module. A communication protocol state machine controller and an I/O refresh state machine controller recognize periodic I/O refresh data frames and nonperiodic state data frames, can instantly send notification to the I/O refresh state machine controller to require the I/O refresh state machine controller to respond to the received state data frames when recognizing the sent nonperiodic state data frames, and can automatically respond and perform data read-write when recognizing the sent I/O refresh data frames so as to lighten the load of the I/O refresh state machine controller and improve communication speed and efficiency; meanwhile, the communication method adopts serial communication lines for connection, has few lead wires and low cost, saves capital goods resource and achieves the aim of the invention.

Description

technical field [0001] The invention relates to a communication method of a programmable logic controller (Programmable Logical Controller, PLC), in particular to a communication method between a programmable logic controller and an expansion module. Background technique [0002] Programmable Logical Controller (PLC) is an electronic device that provides input signals and executes user programs to control output signals and mechanical actions. The number of I / O terminals of existing PLC hosts is Fixed, when more I / O terminals need to be expanded, various expansion modules need to be added to increase the number of I / O terminals. [0003] Existing programmable logic controller PLCs are generally composed of programmable logic controller PLC mainframe plus expansion modules. The connection methods of expansion modules include backplane connection and side step-by-step connection. Since the backplane connection occupies more hardware resources, large installation space and hig...

Claims

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Application Information

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IPC IPC(8): G05B19/05
Inventor 琚长江陈平应成侯金华
Owner SHANGHAI ELECTRICAL APPLIANCES RES INSTGROUP
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