Modbus configuration AC70 controller
Heres a link to the Manual -> https://library.e.abb.com/private/7e5...
Modbus is described in the AC70 Users Guide section 18.104.22.168 (3BUR000874)
Basically you configure a MODCHAN database element to set up the link and then pass data in the PARDAT elements. You will need to install the Modbus driver in the AC70 if it doesnt already have that option.
I have vague memories of configuring a MODBUS interface in the dim and distant past. IIRC it wasnt that hard, but perhaps time has dulled the memory :p