HL6: AT+CMGS returns ERROR several times before succeeding

IoT Modules Legacy HL Series
1

Below you can see the communication between the MCU and the HL6. It appears that sending the SMS fails several times before it works. I see no reason why it shouldn’t work the first time. The retry count is in the area of 10 - 40, sometimes lower. I checked the SMS PDU with the online tool available here http://www.diafaan.com/sms-tutorials/gsm-modem-tutorial/online-sms-pdu-decoder/. SIM unlocking and attaching to the network work fine. I have the *PSNTRG URC enabled so I always know whether I am able to send or not.

22.04.2015 15:57:16.002 [COM24] - AT+CMGS=137<CR>

22.04.2015 15:57:16.004 [COM17] - <CR><LF>
> 
22.04.2015 15:57:16.535 [COM24] - 0011000D91945137245350F60000AA8BC2B75BFDAECB41CDB09C9E768358206519D42ED3E7207619347CB7C569D0BC2E07B5C3F231BACC02D1CB6D78411EA6D7E56510B90C1ABFDDF3F4D95D06C9664316C85E76D3D3EC30BD5C9783AC452795052A87EBA0A7D1C80285EDE531E818D6BB40D330BB4E0FD3D36FF79C05B2BFE9F23228ED2CD341C2371E<SUB>
22.04.2015 15:57:16.547 [COM17] - <CR><LF>
ERROR<CR><LF>

22.04.2015 15:57:48.543 [COM24] - AT+CSQ<CR>

22.04.2015 15:57:48.550 [COM17] - <CR><LF>
+CSQ: 18,99<CR><LF>
<CR><LF>
OK<CR><LF>

22.04.2015 15:57:48.559 [COM24] - AT+CMGS=137<CR>

22.04.2015 15:57:48.566 [COM17] - <CR><LF>
> <CR><LF>
ERROR<CR><LF>

22.04.2015 15:57:49.095 [COM24] - 0011000D91945137245350F60000AA8BC2B75BFDAECB41CDB09C9E768358206519D42ED3E7207619347CB7C569D0BC2E07B5C3F231BACC02D1CB6D78411EA6D7E56510B90C1ABFDDF3F4D95D06C9664316C85E76D3D3EC30BD5C9783AC452795052A87EBA0A7D1C80285EDE531E818D6BB40D330BB4E0FD3D36FF79C05B2BFE9F23228ED2CD341C2371E<SUB>AT+CSQ<CR>

22.04.2015 15:58:21.112 [COM17] - <CR><LF>
+CSQ: 18,99<CR><LF>
<CR><LF>
OK<CR><LF>

22.04.2015 15:58:21.118 [COM24] - AT+CMGS=137<CR>

22.04.2015 15:58:21.128 [COM17] - <CR><LF>
> 
22.04.2015 15:58:21.653 [COM24] - 0011000D91945137245350F60000AA8BC2B75BFDAECB41CDB09C9E768358206519D42ED3E7207619347CB7C569D0BC2E07B5C3F231BACC02D1CB6D78411EA6D7E56510B90C1ABFDDF3F4D95D06C9664316C85E76D3D3EC30BD5C9783AC452795052A87EBA0A7D1C80285EDE531E818D6BB40D330BB4E0FD3D36FF79C05B2BFE9F23228ED2CD341C2371E<SUB>
22.04.2015 15:58:21.656 [COM17] - <CR><LF>
ERROR<CR><LF>

22.04.2015 15:58:53.661 [COM24] - AT+CSQ<CR>

22.04.2015 15:58:53.674 [COM17] - <CR><LF>
+CSQ: 18,99<CR><LF>
<CR><LF>
OK<CR><LF>

22.04.2015 15:58:53.677 [COM24] - AT+CMGS=137<CR>

22.04.2015 15:58:53.690 [COM17] - <CR><LF>
> 
22.04.2015 15:58:54.211 [COM24] - 0011000D91945137245350F60000AA8BC2B75BFDAECB41CDB09C9E768358206519D42ED3E7207619347CB7C569D0BC2E07B5C3F231BACC02D1CB6D78411EA6D7E56510B90C1ABFDDF3F4D95D06C9664316C85E76D3D3EC30BD5C9783AC452795052A87EBA0A7D1C80285EDE531E818D6BB40D330BB4E0FD3D36FF79C05B2BFE9F23228ED2CD341C2371E<SUB>
22.04.2015 15:58:59.173 [COM17] - <CR><LF>
+CMGS: 125<CR><LF>
<CR><LF>
OK<CR><LF>
2

Can you set AT+CMEE=1 and see what exact error is coming?

3

I started using a new SIM card from the same provider and the problem is gone. It appears that the SIM card was worn out due to many slot-insertion cycles. At least that is my theory. Indeed ony I was encountering the issue. Testers didn’t see the problem although I gave them a heads up.

BTW… I double checked the prepaid balance. That wasn’t the issue.

I think here are some people that have used a GSM modem a couple of times more often than I have. Is this a plausible explanation? The SIM card may have been inserted and ejected about 3000 times during the last half year.

4

Again, AT+CMEE=1 to see the precise error code would give more information to go on.

SIM cards are certainly not designed for that kind of service :exclamation:

:open_mouth: