A dynamic adjustment circuit, system and method for a pull-down bias resistor on a 485 bus

Abstract

The application belongs to the technical field of RS-485 bus design, and provides a dynamic adjustment circuit, system and method for pull-down bias resistance on a 485 bus, which adopts a structure of photoelectric coupler and resistance in series to replace a traditional fixed resistance value resistance, adjusts the resistance value of the photoelectric coupler, in the system initialization stage, the program step adjusts the resistance value of the photoelectric coupler, scans and records the resistance value setting interval of normal communication and communication failure of the equipment one by one, and during the normal operation of the system, the optimal resistance value configuration can be dynamically switched according to the communication requirements of different equipment, and the optimal resistance value setting of the corresponding equipment is adopted when each equipment is accessed. This design realizes real-time adjustment of the RS-485 bus bias resistance, and significantly improves the compatibility of the system to different equipment.

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