Yes, I want to use the PIC as the I/O, the code is what I am worried about. I have been doing tons of reading on this and I am just not sure were to start. Do I use the shiftin/out, SPI, etc...I have the circut, with out the pic, only the shift registers and timing circuits breadborded and connected to the PLC backplane, it works and can view the input/output, It is an 8 bit input and 8 bit output on one card. I am useing an Agilent MSO6104A, mixed signal scope with 16 pin logic analizer built in. I can see timing and can show post the jpg of it if needed as well as the schematic in autocad, if that would help in the programming. I am just stuck and need some direction. I didn't want to have to bother the form with all this. But I guess I will have too.