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Hi, I am using 8051 to control teh GSM module. Both are working fine with the terminal commands. But when I send the same command from the controlle rto modem, modem is not responding. i iwant the information from teh modem. so first I send the command and then I activated the serial interrupt to recive the data from the modem. Some where I am missing it out. Can somebody help me in thsi regard.thank you
Search the forum for "GSM" or "GSM Modem" - it's all been said before!
...first I send the command and then I activated the serial interrupt to recive the data from the modem.
You should not wait until you have sent a command to the modem until you set up and enable your serial interrupt routine. You do that first of all, so it is ready to capture all data - including any possible echo from sending the command.
If using interrupts to receive data, it is often smart to use interrupts for sending data too. This leaves your application ready to process other I/O while the command is sent out.
"I send the same command from the controller to modem, modem is not responding."
There are many possibilities:
1. The controller never actually sent anything; 2. The controller sent something, but it was incorrect in some way; 3. The controller did send the correct command, but the modem never received it; 4. The controller sent the command, the modem received it, but didn't respond; 5. The controller sent the command, the modem received it, sent a valid response, but it never reached the controller; 6. The controller sent the command, the modem received it, sent a valid response, it reached the controller, but your software didn't correctly handle it.
You need to determine precisely what is & isn't happening.
Begin at number 1 above, and work your way through...
Note that, for most of it, it is irrelevant whether a modem or any other RS232 device is used - so test it with hypoterminal first...
Learn to debug - see: www.8052.com/.../read.phtml
There are very many things that can stop serial comms from working:
Software - including configurations of baud rate, parity, control signals, etc; Electronic hardware - including the RS232 transceiver; Other hardware - cables, etc.
You need to ensure that they are all correct & working!