Modbus poll on subnet with Metz-connect modbus slave

I have a Nano with a 4 output Triac module connected on modbus on subnet
The network ID a and baud rate are predefined on the module by rotary switch
The discovery is not working ( never showing that an external slave is present)
The modbus poll is not able to reach the module through the Nano.
Could it be that the nano is routing modbus request only whe the slave is in its child on the three.
If yes, how can I add an external module manually and define his property?
The module detail documentation can be found in Metz-connect website

Thanks for help

For now, T3000 doesn’t show 3rd party devices in the Tree. We’re working on it but for now you have to rely on this ‘Network Points’ screen, any external points you use in your program will show up here along with the current status for those items.

But my question is:
How can the nano do its routing between ip and rs485 if the slave is not in its child list?
How can I test manually with modbus poll if the nano does not route the modbus request to the RS485.
Do I need to buy a usb /rs485 converter to connect directly to the slave for testing?

The nano will do a little scanning in the background for new devices. Not as thorough as the magnifying glass at all protocols, all baud rates, but it listens for bacnet packets and polls at the current baud rate in the case of modbus.