Equipment phases on AB Logix controllers

[piratedan200]

Has anyone used the equipment phase program type on AB Logix controllers? It seems like it's more geared towards programming in SFC, but you can use LD or ST too. Just curious if it's worth spending time looking into it as a programming method.

 

[Paullys50]

They are used primarily for batch process and working with ISA-88 concepts however I use them all the time for anything that requires a state machine and sequence. Makes it easy to standardize on keeps things modular.

 

[cardosocea]

I've started looking at this as I have a batch process to automate and I think what gears the SFC programming is really the sequencing. Instead of writing a sequence in ladder with bits in a DINT for steps, it displays nicely with indication of where the process is at.

If used with PlantPAx elements or process strategies it's even cleaner as a lot of the code is "hidden" away in a sub-routine.

The Equipment phase helps to have dedicated code that runs in different stages. You'll notice as well that if you were to code the Holding, Stopping or Resetting stages you probably wouldn't use SFC as a lot of times there won't be a sequence as such and it's more of a single waiting state for valves to close and motors to stop rather than a sequence.