Watch the EGCP2 units. If I remember correctly, they list the words a being type 3 but they are really type 4 (read only). I think it is the usual confusion with Modbus/Jbus and addressing starting at either 0 or 1. The word type is pretty easy to change on line though. That is a blessing.
I know with Omron for some reason I often get words/bytes swapped. Just watch for that also. You really hjave to know what you are looking for in the way of a response. Say it is voltage, if the bytes/words are swapped, it is pretty easy to figure out. If it is varying current, then that is another story. Once you sort out one value you generally have no problems sorting out the others as they will be identical.
Some slave devices have a "big endian" "little endian" function. That is a huge help. I do not think the EGCP2 has that facility.