RS485 communication circuit

Abstract

The invention relates to a RS485 communication circuit which can be used for enhancing the anti-interference capability and drive capability of RS485 communication and uses a sending signal to indirectly control the receiving / sending direction to lead a main control chip not to independently process the control of data stream direction. The circuit comprises a power supply isolation module (10), the main control chip (20), a signal photoelectric isolation module (30) and a communication interface module (40); wherein, the power supply isolation module (10) generate 5V isolating power source which is used for supplying power for the communication interface module; the signal photoelectric isolation module (30) includes a data receiving signal optical isolation circuit (31) and a data sending signal optical isolation circuit (32), wherein, the data receiving signal optical isolation circuit (31) is respectively connected with the main control chip (20) and the communication interface module (40), and the data sending signal optical isolation circuit (32) is respectively connected with the main control chip (20) and the communication interface module (40); the communication interfacemodule (40) comprises a receiving signal shaping drive circuit (41), a data sending control circuit (42), a RS485 communication interface chip (43) and a bus interface circuit (44).

Description

technical field [0001] The invention relates to an RS485 communication circuit, more specifically, relates to an RS485 communication circuit applied to an intelligent automation device in the field of industrial automation monitoring. Background technique [0002] Usually, in the field of industrial automation, such as in the substation monitoring system, the terminal data acquisition block usually adopts a distributed acquisition method, and the measured data, such as voltage, current, power, etc., are generally connected to the background monitoring system through the field bus. There are many types of fieldbus at present, such as RS485 bus, CAN bus, Profibus bus, DeviceNet bus, Longworks bus and so on. Among them, the RS485 bus is widely used in intelligent automation devices in the field of industrial automation monitoring because of its low hardware cost, easy implementation, and good reliability. [0003] The RS485 bus is a half-duplex bus. It is used in industrial si...

AI Technical Summary

Problems solved by technology

[0005] The shortcomings of the current technology are as follows: firstly, because the device is used in industrial occasions, there are a large number of electromagnetic interference signals around the device, including some interference signals introduced from the RS485 bus, and the interference of the internal circuit of the device, making the bus communication capability of RS485 Actual performance reduction, e.g. shortened communication distance, reduced number of connected nodes on the bus

Secondly, the main control chip and the communication interface chip need to be connected with three signal lines to realize RS485 communication. Among them, the receiving / sending direction control line (Control) needs the main control chip (CPU) to perform program control according to the current direction of the data flow. cumbersome

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