PLS8 prolonged higher current drain. | Telit Cinterion IoT Developer Community
November 18, 2020 - 11:37pm, 3755 views
Hi,
We are experiencing some strange behaviour with a tracking product we produce using the PLS8. In normal operation these trackers requires an average current of about 70 mA with the PLS8's GPS engine running. Current will peak to about 240 mA during network activity and then drop back to the 70 mA average. Under the operational state where we're seeing the problem, devices are simply connected to the cellular network waiting for any incoming SMS commands. Devices are not connected in any way to the internet in this state The microcontroller operating the PLS8 sends the AT command, "AT+CPMS?", periodically to check for incoming messages (we also have URC set to report incoming messages but found that to not be 100% reliable). Very occasionally, current will increase to about 240 mA during network activity but then stay at that level. Sending the device an SMS command causes the current drain to return to a normal 70 mA average as soon as the message has been received. It's as if the PLS8 starts some sort of continuous cell network activity. Would you have any idea what might be going on here please?
Thank you,
Ed Haslam
Hi Bartłomiej,
Thanks for your reply. results of the ATI1 command are:
Cinterion
PLS8-US R4
REVISION 04.004
A-REVISION 01.000.06
This phenomenon is observed sporadically whenever there is a valid APN name available. The problem never occurs when the device has an invalid APN. An A-GPS file download including creation of the socket to do that, does not need to happen for the problem to occur. Devices needn't have been involved in any sort of data services and can simply be operating SMS only. Also, this happens primarily with Bell Mobility although it does occur on occasion with other carriers. When a device is sitting idle, simply registered to the network and awaiting any SMS messages, why would current suddenly jump to a sustained 250 mA level for minutes to an hour or more in a random and only occasional fashion? Why would current then consistently return to the normal, 60 to 70 mA level for the next few hours or days, any time an SMS message is received and an acknowledging SMS sent? Why would devices not show anything unusual happening either in the diagnostics you've suggested we output or any URCs that happen to be generated while the elevated current consumption is occurring? This has now been observed with several devices. I feel like the clues are there but don't have the in-depth cellular knowledge to figure out what's happening. If there is no easy answer, could you please let us know your recommendations for the best way to configure the PLS8 for minimal current consumption while registered to the network and simply camped, waiting for an incoming SMS message?
Thanks much,
Ed
Hi Ed,
I haven't found any similar customer report.
For test you might also set a valid APN and force 3G or 2G with COPS command or even disable 4G bands with AT^SCFG command ("Radio/Band" parameter) and observe if this happens again or not.
On the other hand if you noticed that it is does not depend on the fact if there was a data transmission before or not, maybe this is somehow related to short messages then which are commonly used by your application, especially that you observe that SMS reception can stop this.
Please experiment with SMS settings. Please check AT+CGSMS setting - service preference for mobile originated short messages (PS or CS). Then please also check "SMS/4GPref" setting in AT^SCFG? output to check if SMS over IMS is enabled.
Best regards,
Bartłomiej