I have a linux system where I want to use an MC7354 to receive SMS messages . I have an application that opens the port (/dev/ttyUSB2) and sets they MC7354 to receive messages and send to the terminal in PDU format (at+cmgf=0 and at+cnmi=1,2).
This works using other modems from other vendors. It works for the MC7354 for 50 messages, and then the MC7354 stops notifying the terminal that any messages are received. I have also seen this with the MC7304, so I believe there may be some sort of common issue with this modem family.
Has anyone seen this sort of problem or know of a way to fix it?
I updated to the latest firmware (Build4544-Approved-7354-EXE) but doesn’t seem to fix the problem.
Hi,
I also faced the same issue with SMS on MC7304.This issue is observed only with at+cnmi=1,2 setting. with other settings it’s working fine.
I found that it’s because there is no eough memory.
The RAM can be release if you set up the testing with following steps.
at+cmgf=1
at+cnmi=1,2,0,2,0
at+csms=1 //this command tell the ME that the TE shall send an ACK to the ME when a SMS is received.
send the SMS to the modem.
Each time the SMS is recived input at+cnma to the modem, at+cnma tells the ME the SMS has been received by the TE please release the buffer.
You can see my AT log in attachment
-Alex ATlog.txt (3.86 KB)
I finally had time to get back to testing this. It appears that you found the solution. Sending an “at+cnma=0” allows the message to be acknowledged and I can continue to receive messages. I don’t think this should be required since I have “at+csms=0”, but it works so I can move on to other things. Thanks for your help and observations, this allows me to move past this problem.