Interface Productivity P2 and Weintek HMI

First time with Automation Direct Productivity. Using P2-550.
1) How do I interface to a Weintek HMI? Model MT8101ie. It has drivers for CLICK, DIRECT, DO-MORE, and ETHERNET. If Modbus is the best way, please give details on addressing.
2) How do I see the "C" address assignments on internal tags? I see them when I export tags.

Response from AD Tech Support:
"...Productivity CPUs support Modbus RTU (from the RS232 and RS485 ports), Modbus TCP from the Ethernet port and Ethernet/IP also from the Ethernet port. The easiest way to communicate to a Productivity CPU from a 3rd party HMI would be Modbus RTU or Modbus TCP with the Productivity as a slave. In the productivity suite software go into the tag database. From here you can assign Modbus registers to individual tags. If you want to group them then use arrays and assign the array a group of Modbus registers/coils..."

I set Weintek for Modbus RTU. Read and writes both starting with 0x. Seems to be working so far. Easy.