Our base model ConnectPort Display has support for Elo USB touchscreens, via a firmware update. The Elo driver is not required on the Host PC in this situation and the calibration is handled by the ConnectPort Display. I can send you the respective firmware if needed.
The newer model ConnectPort Display M22 does not yet have support for Elo USB touchscreens, although this is a high priority so I expect it to be added soon. This will also be achieved via a firmware update.
Both model ConnectPort Displays support any kind of RS-232 (serial) touchscreen. The Digi RealPort driver would need to be installed on the Host PC to allow the Host PC to interact with the touchscreen in this case.
Let me know if you have any further questions.