母板通过FR232R芯片及其外围电路实现USB接口转UART（TTL电平）接口，并提供自定义的双列插针扩展接口；功能子板则分为RS232接口和TTL接口两种，并可根据需要设计RS485/RS422/CAN总线接口。-Motherboard chip by FR232R USB interface and its peripheral circuit switch UART (TTL level) interface, and provide a custom double-row pin exp