I found a great powerpoint by Frank Petruzella,
Frank Petruzella wrote:
"The main difference between the two is the SQC instruction is considered to be an output element in an SLC 500 program, whereas, the SQI is considered to be an input element in a PLC-5 program. Unlike the SQI instruction the SQC increments its position when its control logic goes from false-to-true. Since an output element cannot be used to control another output element, an additional status bit, called the found bit (FD) has been added to the control element for an SQC. The FD bit goes true when the source input pattern matches the sequencer file word pattern that it is being compared against, and false if the words don't match. The FD bit can be examined in the control logic that increments the SQO and SQC so that they increment together..."
This is good information. It looks like the SQC is used like an SQI but instead the FD bit is used to increment the SCQ instead of just the SQI and SQO working together.
This helps me ALOT. My big question now. Is there any difference with the function of the PLC5 SQI and the CLX SQI instructions.