I am using the OPTO 22/Modbus TCP protocol with a Direct Logic 06 PLC. My application is very old. They used B1 and B2 OPTO cards with OPTO I/O and the DL06 PLC. They used LabView to tie it all together. I am trying to convert it to PAC Control and PAC Display. I have upgraded the B1 and B2 boards to E1 and E2 boards. I can read the data fine. I am having trouble writing data. Working on that now.