COM port of 1 The PC is RS232 level, not TTL level, and the levels are incompatible.

2. Baud rate and communication format. It should be set to serial communication with level change, so that MSComm can receive valid data, but a simple 5V is not enough.

Solution:

If you just judge whether the peripheral is powered on, just take a light-emitting diode and have a look.

If you must look through the serial port on the computer, add a small device, and the peripheral has electricity to send an agreed data according to the serial port data communication. MSComm in VB can be used to receive and judge.

If you need help, please email me Billy @163.com.