Compact Logix - Launch SFC Routine in Power-Up Handler?

Hello, I'm new here and new to AB programming. I come from the land of DeltaV

I have a CompactLogix 1769-L1, and found out how to programatically reset fault code 01, and type 01 after a power failure by reading the AB manual. I did this with a ladder routine and GSV/SSV instructions like they show in the manual. I added another routine to the Power-Up Handler that is an SFC, and have the ladder JSR to the SFC after the power-up fault is reset. My problem is the SFC starts and the first step completes, but it won't transition to the next step (even if I try and force the transition.) Do you know if the routines in the Power-Up Handler only execute for a single scan, or something like that? When do Power-Up Handler routines stop executing? It looks like both the ladder and SFC are active when I go online because they have green borders around them.

Welcome to the PLCTalk forum community !

The power-up handler does execute just once. LD and ST routines are the most appropriate for execution in that task.

I'm not sure if you could execute an SFC with a FOR instruction instead of a JSR and get the behavior you expect, or not. In general, SFC transitions are based on changes and time, and a routine that executes just once isn't an ideal place for that.

In general SFC actions are ST anyhow, so I would simply call those ST routines one after another with JSR's from a main ladder (or another ST) routine.

The "green borders" just mean the controller is in RUN mode; they don't indicate that the routine is actually executing.

Thanks Ken! I thought that's what was happening (executing once then stopping). I was able to use just LD to get it working. I hadn't thought of using ST, but I'll keep that in mind next time. Also, thanks for explaining what the green border indicates. Much appreciated!