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Firmware (TRB2_R_00.02.04.1) 

In Modbus TCP Slave mode, many of the dynamic registers cannot be read.
Basic value registers such as "System Host Name" and "System Uptime" can be read, but the "Modem ID" and most importantly the "IMSI" cannot be read. 

We need to be able read the IMSI out of the device to identify it. 

Only about half of the advertised registers are able to be read successfully. 

None of the Modem parameters can be read. 

This may be linked to the fact that GSMCTL commands do not work in the CLI (which these registers may require??)

1 Answer

+1 vote
by anonymous

I did not test the function but from memory, if the SIM card is not active (or not inserted), then Modbus requests to the registers concerning this one are rejected (Operator name, RSSi ...)

It would be really good if they are not, even if it means returning a "N/A" value because it crashes the n-words read requests.

For example Function Code FC3 - Register 2 - Length 6 registers

Uptime / RSSi / Temperature.

If the SIM is not inserted, then the whole query is rejected and it must be split into 2 queries

- Uptime (Register 2 - Lenght 2 registers)

- Temperature (Register 6 - Length 2 registers)


Hi Goderef

The SIM is definitely inserted, and the router is connected to the cellular network (Cat-M1), has an IP address, and is connected to the internet (eg it is using the SIM card so has definitely been read and the modem is definitely able to communicate).

We have set up the Router as a Modbus TCP Slave.

We query these registers from our remote server (TCP CLI client connected over an IPSec tunnel)

We can read some of the basic registers. 

Reading any of the "Modem" registers crashes the TCP CLI client. 

It seems that the Modem can't be found. 

GSMCTL commands run locally on the Router also fail for any of the Modem reads. I have also raised this issue at:

Hopefully someone can shed some light on this.

Test on TRB145 - All working perfectly

Test on TRB255 - All broken

The SIM is there, the router is using it, but it is not available to the user interface, or the CLI, or the Modbus TCP Slave registers.