TRB500 - Lock to cell problems

shoei600 · October 13, 2024, 8:36am

Please help. I’m having trouble getting cell lock to work on TRB500. I have two strong cells nearby that are slow and high latency, much faster cell tower further away with much faster speeds and lower latency.

The slow towers use band 3 and the fast tower uses 3, 7 and 20. Disabling band 3 allow connection to 7 and 20 on the desired tower but I need band 3 too as this is where the real speed and coverage is.

Some TRB500 responses:

root@TRB500:~# gsmctl -A 'AT+QNWLOCK=?'
+QNWLOCK: "common/4g",(0-10),<freq>,<pci>
+QNWLOCK: "common/5g",<pci>,<freq>,<scs>,<band>
+QNWLOCK: "save_ctrl",(0,1),(0,1)type or paste code here

**ERROR**
root@TRB500:~# gsmctl -A 'AT+QENG="SERVINGCELL"'
+QENG: "servingcell","NOCONN","LTE","FDD",234,30,33E305,260,1761,3,3,3,580D,-61,-10,-33,12,7,-400,-

root@TRB500:~# gsmctl -A 'AT+QENG="NEIGHBOURCELL"'
+QENG: "neighbourcell intra","LTE",1761,260,-10,-61,-34,-,-,-,-,-,-
+QENG: "neighbourcell intra","LTE",1761,259,-12,-63,-41,-,-,-,-,-,-
+QENG: "neighbourcell inter","LTE",1617,260,-10,-61,-30,-,-,-,-,-
+QENG: "neighbourcell inter","LTE",1617,259,-13,-66,-43,-,-,-,-,-
+QENG: "neighbourcell inter","LTE",1617,266,-20,-74,-47,-,-,-,-,-

*** +QENG: "neighbourcell intra","LTE",3179,271,-6,-101,-76,-,-,-,-,-,-                                                                                                                  
+QENG: "neighbourcell intra","LTE",3179,204,-6,-104,-89,-,-,-,-,-,-                                                                                                                  
+QENG: "neighbourcell intra","LTE",3179,189,-18,-115,-88,-,-,-,-,-,-                                                                                                                 
+QENG: "neighbourcell intra","LTE",3179,270,-20,-114,-84,-,-,-,-,-,-                                                                                                                 
+QENG: "neighbourcell intra","LTE",3179,206,-15,-113,-89,-,-,-,-,-,-                                                                                                                 
***+QENG: "neighbourcell inter","LTE",3350,271,-8,-102,-74,-,-,-,-,-                                                                                                                    
+QENG: "neighbourcell inter","LTE",3350,189,-20,-112,-82,-,-,-,-,-                                                                                                                   
+QENG: "neighbourcell inter","LTE",3350,204,-8,-106,-87,-,-,-,-,-                                                                                                                    
+QENG: "neighbourcell inter","LTE",3350,206,-12,-109,-87,-,-,-,-,-                                                                                                                   
+QENG: "neighbourcell inter","LTE",3350,213,-19,-118,-85,-,-,-,-,- 

root@TRB500:~# gsmctl -A 'AT+QCFG="NWSCANMODE",3,1'

I would like to connect to PCI 271 (shown as ***) with bands 3, 7 and 20 and have been using these commands:
gsmctl -A 'AT+QNWLOCK="common/lte”,2,1617,271,3350,271,3179,271’
gsmctl -A 'AT+QNWLOCK="common/4g”,2,1617,271,3350,271,3179,271’

The command line tool just returns > prompt and sits there forever until I break out, it seems not to recognise the command as complete. Please let me know what I should send.

Thank you.

Marija · October 14, 2024, 8:12am

Hello,

If you are comfortable using the device’s WebUI, I recommend locking the bands through it, as it is easier. To lock the bands, navigate to Network → Mobile → Connection in the WebUI and change the Band selection to Manual.

For more information, you can refer to our wiki: TRB500 Mobile Connection.

Best regards,

shoei600 · October 14, 2024, 8:17am

Hi, unfortunately I still need band 3 which is available from at least three towers buts its only one tower I need, the other two are slow and highly latent. I need to be able to lock the modem to a specific cell/tower and three bands.

Marija · October 14, 2024, 8:43am

Unfortunately, cell locking is not supported on the modems. However, if you understand the potential stability risks, you can check out the following posts for more information:

Best regards,

shoei600 · October 14, 2024, 9:29am

Hi Marija,
I understand it may not be fully supported officially but even the commands in this Teltonika guide are not working so who else can we turn to for support other than the authors themselves?

https://wiki.teltonika-networks.com/view/Locking_Devices_to_a_Mobile_Cell

**gsmctl -A 'AT+QNWLOCK=?'**
- returns, below which shows supported:
+QNWLOCK: "common/4g",(0-10),<freq>,<pci>
+QNWLOCK: "common/5g",<pci>,<freq>,<scs>,<band>
+QNWLOCK: "save_ctrl",(0,1),(0,1)

gsmctl -A 'AT+QCFG="NWSCANMODE",3,1' 
- returns 'error'

I had seen those guides but didn’t help my situation much, must the cells be visible in ‘neighbour cell’ search prior to locking to lock? they are swamped out by the local masts so I may have to take the modem next to the tower if that’s necessary.

Thanks.

Marija · October 14, 2024, 9:36am

As mentioned on the wiki page you provided, “If the model starts with EG, EC (Quectel), or SLM (Meig), and not RG (5G devices), this feature should work.” In your case, since you have the TRB500, which is a 5G device, that is why the commands provided are not working on your device.

I hope this clarifies things a bit.

Best regards,

shoei600 · October 15, 2024, 8:44am

No, not really. I did see that statement but both of the posts you linked to (and others) all show 5G devices having successfully employed cell lock, even the same TRB500 units.

Daumantas · October 15, 2024, 9:50am

Hello @shoei600 ,

The commands you’re executing are correct, but contain some syntax errors, mainly the different quotes at the beginning and end of the command. Additionally, the number after "common/4g” indicates the number of cells provided. Since you’re providing 3 cells (1617+271, 3350+271, 3179+271), the number in the command should be 3.

It should be noted, that this command only locks the device primary (PCC) cell, and secondary cells (SCC) cannot be controlled using cell lock. This should not be an issue, as the carrier configuration will likely only allow the device to connect to the cells with the same PCI. The TRB500 should also prefer higher bandwidth bands as long as they provide acceptable signal levels.

For a better experience, instead of using gsmctl utility, I would suggest entering AT commands into the Modem debug section in the web interface:

Using this utility, AT commands can be sent without any additional syntax. So in your case the command would be:

AT+QNWLOCK="common/4g",3,1617,271,3350,271,3179,271

As my colleague mentioned, and is added on the Wiki article, this feature is not officially supported neither by Teltonika, nor the modem manufacturer Quectel:

So if you experience any stability or performance issues, please disable cell locking by executing the following command:

AT+QNWLOCK="common/4g",0

Best regards,

shoei600 · October 15, 2024, 10:22am

Thank you, this is working.

I did try 3 initially thinking it was setting the number of parameters but then found the protocol from Quectel that was different.

This is working - thank you so much.

Daumantas · October 15, 2024, 10:26am

Glad to hear that!

system · October 17, 2024, 2:26am

This topic was automatically closed 40 hours after the last reply. New replies are no longer allowed.