Dear All, I'm using the s7plc driver to monitor and control an RF modulator which has a PLC sending a 253byte data array and receiving a 16byte data array to/from my IOC. I did some test using the PLC server emulator (server.tcl) which was into the s7plc folder and all is nice and working right! I obtain the right process variable (PV) values I expect!!! But when I connect my IOC to the real PLC I have problems with the PVs. The PV values sometimes are correct and often wrong! Do you have any idea about the possible causes? Thanks in advance. Regards, Gianluca