I'm working in a project where we must communicate an Omron CJ1 with a Siemens S7-300. The fist idea was using OPC connectivity by means of a bridge PC, in order to have a simple and fast system integration. Later, a Siemens technician told me that by using TCP/IP protocol by Ethernet, it was possible to directly exchange data between the PLC's.
As I know, Omron uses the propietary FINS message structure, while Siemens uses the Industrial Ethernet propietary message structure. So I suppose the communication is not direct and the programation has to decode each message in order to "understand" one each other. This implies a more difficult and long integration work than using OPC.
Am I right with this idea?