使用“ GNET”协议与USB设备进行串行通信

Question

I have a USB device with the following specification . Page 22 describes the GNET protocol that should be used to interact with the device.

The connection is fine but the device just doesn't give me any response, so I think I am not sending the correct data to it, maybe missing the handshake?

From Specification

Support TTY (TELE TYPE) OPERATION - Use TTY to send commands and messages

Use ASCII value for each field and use Separator "," between two Fields.

connect_and_send.py

import serial

port = "COM3"
baud = 9600

ser = serial.Serial(port, baud, timeout=1)

if ser.isOpen():
    print(ser.name + ' is open...')

# STX, N, CR
to_send = b'\x02\x4e\x0d'
print "Sending {}".format(to_send)
ser.write(to_send)
out = ser.read()
print('Receiving...'+out)

COM3 is the correct port:

Any help and guidance would be greatly appreciated.

Answer 1

You have never​ to use \\x4e , this is the Negative Acknowledge from the device.
Try

to_send = b'\x02F\x0d'

to get Firmware Version

Answer 2

I contacted the supplier in the end and the issue was setting to wrong baud rate. Changing from 9600 to 19200 resolved the problem.