2 LM in the same network

[emme]

Hi

I'm in the process to include serveral modbus fancoil in my organization, they are altready wired together, but I miss a client to role them all and read statuses 
the main LM, the BMS, is located at floor -1, the devices are at 4th floor and I cannot wire them.

My idea is to connect a new LM on 4th floor and use it as Modbus gateway to connect those fancoils.

My question is....
how the second LM can communicate with the first one?

in my intention I do need to read all registers and synch them to the first one as virtual objects. The BMS will also need to command them to start/stop and setpoint

I have LAN access available and I have no other ideas than http API (multicast is not an options)

is there another way? 

thanks
Marco