Q: How to find and solve modem connection failures
A: Four possibility’s:
- (1) The modem has gone defect
- (2) SIM problem
- (3) Problems logging in to the server <TCP, FTP, HTTP, MQTT, EMAIL>
- (4) Provider selection problems
When the “Send interval” arrives, the modem is fired-up, registered on Internet and data is send (using the chosen protocol) to your Server.
If data is no longer retrieved and the data logger can’t be reached using remote connection scheduling to connect to the data logger, USB (physical) or BLE (local area on-line) access is needed.
Check for system messages to pinpoint the problem:
- (1) IMEI_CHECK The modem has gone defect or the modem flash memory has become corrupt.
- (2) SIM_DETECT The modem is unable to communicate with the SIM card.
- (3) ERR <protocol>; WDT; <Server or Network related information>
- (4) AT+CEREG=2;+CEREG?; +CEREG:2,2;ERR; <Network registration error>
T: (1) IMEI_CHECK:
Flash memory corruption can be prevented by installing a firmware version equal or higher than V5.1 B1. From this version (and up) modem voltage dip and over temperature protection is enabled.
Modem flash corruption can be repaired by re-flasing the modem. (Only if the data logger is still under warranty. To verify, drop a call to support with data logger type and serial number).
If the modem chip has died, the data logger can’t be repaired.
T: (2) SIM_DETECT:
Check for contact problems (card and cage) or replace the SIM card.
T: (3) ERR;<protocol> + WDT;<info>:
Read this FAQ on network connection problems if that applies to the error message.
T: (4) ERR;<Network registration error>:
Since 2G support is ending, 4G with LTE-M is preferred.
Sometimes, NB-IoT will be used (as a backup or alternative). Be aware that NB-IoT has to be used with a fixed Provider in the modem settings (PLNM code). This will speed-up registration, roaming problems are avoided and switching between available providers is prevented. (The strongest provider signal will be selected).