I bought on taobao is the most common kind of module, also pick up on line, a serial port can open, is sent AT later don't get any data, online said work normally on a red light blue and I are normally on the lights!

CodePudding user response:

TXD and RXD two cable for try!

CodePudding user response:

Check the wiring is correct, it is TTL or rs232, baud rate and parity, instruction is correct