Am I right in saying that currently there are only drivers for Modbus TCP which means both the PLC and HMI need to have an ethernet port?
Does this also mean that the HMI needs to support Modbus TCP?
You are correct, the ModbusTCP driver only works over an Ethernet connection and the PLC must support the ModbusTCP protocol.
If you are using an Allen Bradley PLC or Beckhoff TwinCAT PLC, there are specific drivers for those.
This is probably a very dumb question but what is/are the operating systems of HMI's or are they software independant? Can you simply write the program and load the .exe onto the hmi?
AdvancedHMI requires a Windows XP/7/8 operating system. The proprietary HMI panels (e.g. PanelView, C-More, EZ-Panel, Red Lione G3, etc.) run their own operating system and require their proprietary software to program the HMI.
The is one of the selling points of AdvancedHMI. If your hardware running AdvancedHMI goes bad, then anything that runs Windows can be used to replace it. If one of the proprietary systems have a hardware failure, you are locked in to getting a replacement of the same piece of hardware.