Re: EPS / PLC

[stein@aps.anl.gov (S. Joshua Stein)]

I'd just like to clarify a few things:

Not to pick nits, but the GE system used for the APS PSS is the 90-70. To my 
knowledge there isn't a 90-50 series. Basically, as was mentioned before, the
difference between the '30 series and the '70 is that the 70 uses a VME (P1)
backplane, while the 30's is a custom GE thingy (I believe it's a 3U form factor).

Also, the way we are communicating status information into EPICS is actually
via RS-232. To borrow Pete's diagram:

PSS Chain 'B' (GE) -> GE Coprocessor (RS-232) -> Fiber modem -> Fiber -> Fiber
modem -> IP-232 -> MV162 -> MV167.

We're using the fiber due to some long runs.

With regards to the ongoing debate over Ladder logic vs. State logic:

 Right now I would have to say that AB's ladder logic/sequential function chart
paradigm is MUCH more robust than the GE/Fanuc State Logic model. I do think
learning/reading/programming state is many times easier than ladder, but there
are quite a few things about state as implemented by GE/Fanuc that show it's 
immaturity. I do correspond quite frequently with the people at Adatek (they
are the source of ECLIPS - the GE development platform for state) regarding
compilier screw-ups and whatnot. They seem receptive and willing to make changes
so there is hope.
  Don`t get me wrong tho, I wouldm't trade a day programming state for ladder
anytime soon!

<Josh>