I had a module here. direct read from the local Q PLC is very fast. 50000 Datawords to a DB2 Database is less than a second. If I read 50 000 DW from a connected Siemens PLC it takes me 2 sec from the Siemens CPU port. To read the 50 K from a connected Siemens interface is 8 sec. To read the 50000 DW with a OPC server (from the Siemens) will take 10 sec. and I don't have the store and forward function, that means in case of IT problems the datas are gone. The module is very fast to learn and I have a demo module with all drivers. Siemens, Rockwell, Mitsubishi. It make it very easy and flexiable to communicate to other PLC systems. Do someone has experience with the Rockwell driver?