Extended bus system

Abstract

The invention provides an extension bus system for a programmable logic controller, which comprises a bus for a main central controller module of the programmable logic controller and a bus for one ormore extension modules, and the extension modules are serially cascaded through the extension bus system. The expansion bus system comprises an expansion bus signal and a low-voltage differential signal so as to realize point-to-point or point-to-multipoint connection, and has the advantages of low power consumption, the low bit error rate, low crosstalk and low radiation.

Description

technical field [0001] The invention relates to the field of automatic control, in particular to an extended bus system. Background technique [0002] In the field of automation control, due to the number of control objects and the requirements of functional diversity, it is usually necessary to support multi-level expansion modules on the basis of the central processing unit module. The existing programmable logic controller (Programmable Logic Controller (PLC)) expansion bus or backplane bus system can generally be divided into two categories. One is that for medium and large PLCs, etc., a high-performance main control chip (for example, a central processing unit (Central Processing Unit (CPU)) etc.) plus an application specific integrated circuit (Application Specific Integrated Circuit (ASIC)) protocol chip and / or The field programmable gate array (Field Programmable Gate Array (FPGA)) is used to connect and communicate between the main CPU module and the expansion modu...

AI Technical Summary

Problems solved by technology

Therefore, the number of connections, functions, performance, etc. of the expansion modules will be limited accordingly

Some higher-speed bus interfaces of the MCU, such as the Serial Peripheral Interface (SPI), can be used for relatively high-speed data transmission, but the signal is usually used for short-distance transmission on the printed circuit board, which is not suitable for Bus connection between CPU and expansion modules of industrial control equipment such as PLC with long distance and poor electromagnetic environment

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