IDEC CLIP Software Question

[T Gibbs]

I have a machine with an IDEC FA1 Jr PLC. I'm looking at putting in a more modern processor. I was looking at the ladder and I understand the addressing other than some rungs like this:

[F 200]-----------------------------------------------------------------------(654)
3

[F 200]-----------------------------------------------------------------------(640)
10

I can't figure out what the F200 is. There is also F201, F202, F203, and F204.

 

[T Gibbs]

:beer:OK. Had a brain ****. That's a counter accumulator. I see it now.