The DF1 protocol with a simple modification to make it work on WinCE has now been used in an actual application.
You can read a little about it at:
http://www.plctalk.net/qanda/showthread.php?t=32269.
Protocol was tested over DH485 using a 1770-KF3 from Allen Bradley. Works without a problem.
Simply change the TargetNode property to the node of the PLC you want to read/write and it works nicely.
Control was very easily ported to work on compact framework. I have tested it to work nicely on a Windows CE device and on a Pocket PC (Compaq IPAQ).
Look for future release of utilities to read and write PLC data tables from a Pocket PC.
