It is possible to get RSSI information from both modems, however, the process is not straightforward.
The first thing you need to check are the id numbers of modems in your router. To do so, login to the router via SSH and enter command
- ubus call gsmd get_modems.
This will output modem details, including the id of each one. Next, to retrieve the RSSI value associated with the modem, you need to write the modem id into the registers starting with the number 329.
Considering that the ids are provided in an ASCII format and the MODBUS request testing functionality only accepts integer values, I suggest using QModMaster app for local testing to write the modem id register value, which accepts hexadecimal input. To convert ASCII to hexadecimal, you can use this online converter.
By replacing id number you can now get the RSSI of a secondary modem by reading 2 registers starting from register number 4.