SARA-R42 - Application note
UBX-20050829 - R02
Monitoring module status
Page 38 of 58
C1-Public
9.2
Full-stack watchdog: how to react to unexpected conditions
The application shall properly handle communication or connectivity problems that can arise when using the module in the cellular mobile
environment.
When a problem at a specific level is encountered, the countermeasure for that level should be tried and, if that does not resolve the issue, then
proceed with the solutions for the lower levels.
shows a full-stack watchdog for monitoring SARA-R4 series modules.
Level
Problem
Countermeasure
AT commands / actions Notes
Socket/dial-up
Cannot send/receive data
Close and re-open socket
AT+USOCL=<socket_id>
AT+USOCR=<protocol>
AT+USOCO=…
Disconnect and re-connect dial-up
Send
+++
/ Move DTR
ATD*99***<cid>#
IP/PDP
Cannot get an IP address;
cannot establish dial-up
Detach/re-attach
AT+CFUN=0
AT+CFUN=1
Consider possible restrictions to multiple <cid>s
active for APN.
If IPv6-only PDN is set in Verizon Wireless MNO
setting, detach/deactivation may be caused by failing
IPv6 acquire by SLAAC. The retry is managed
automatically based on VZW DR logic. Automatic
deactivation does not apply if UL data is disabled via
+UMNOPROF: 9,0.
Deactivate/re-activate context (<cid> != 1)
AT+CGACT=0,<cid>
AT+CGACT=1,<cid>
Network registration Cannot register
Detach/re-attach
AT+CFUN=0
AT+CFUN=1
AT+CFUN=0/1 has to be preferred for registration
cycles.
Moreover AT+CFUN=0/1 is faster than
AT+COPS=2/0.
RF
Cannot register
Disable/re-enable RF functionality
AT+CFUN=0
AT+CFUN=1
AT+CFUN=4 is NVM persistent, better to use
AT+CFUN=0.
Module FW
Cannot register
Soft reset
AT+CFUN=15
AT interface
No response from module
HW switch off
GPIO power control
See the SARA-R4 series system integration
manual
for details and alternatives.
Table 11: Full-stack watchdog for SARA-R4 series modules
