The Application of Modbus TCP in Universal Testing Machine

Aiming at instability and low speed of longdistance communication with serial links in traditional universal testing machine, a universal material testing machine controller based on Modbus TCP is designed. The hardware circuit of the controller is designed with STM32 microcontroller as the core and also includes signal acquisition circuit, servo driver circuit and communication circuit. Depend on the programmable ADC chip, the offset compensation and channels gain can be programmed through software. The Freemodbus protocol stack and LWIP protocol stack are transplanted based on RT-Thread to communicate by Modbus TCP. The test results show that the universal testing machine controller has the characteristics of strong real-time performance, convenient correction of system parameter, and stable communication.