First, to increase your understanding of AT commands in general, read the V.250 specification. That will go a long way in making you an AT command expert. Then for the actual implementation, I do not know Codesys, so the following is pseudo code of the structure you should have for handling AT commands: the_modem = … Read more
Blog post Serial RS232 connections in Python import time import serial # configure the serial connections (the parameters differs on the device you are connecting to) ser = serial.Serial( port=”/dev/ttyUSB1″, baudrate=9600, parity=serial.PARITY_ODD, stopbits=serial.STOPBITS_TWO, bytesize=serial.SEVENBITS ) ser.isOpen() print ‘Enter your commands below.\r\nInsert “exit” to leave the application.’ input=1 while 1 : # get keyboard input input … Read more
You should never, never, ever use sleep as a substitute for waiting for the Final result code from the modem. Just as you would not write a http client that completely ignores all responses from the http server, you should not send AT commands to a modem and completely ignore the responses it sends back. … Read more