Hi everyone,
Filler on line 2. PanelView Plus 7 running FactoryTalk View ME, CompactLogix 5370 L30ER behind it on V32. Operators type a fill setpoint on the Fill screen, the number takes, then about a second later it goes back to 50. Every single time. They've been running the line by holding the button down half a second early, which isn't great.
I power cycled the panel twice, once with the PLC as well, and that changed nothing, so then I checked the numeric input object and it does point at Fill_SP_1. Watching the tag online in Studio 5000 it goes to whatever they type and then straight back to 50, so the panel's writing it fine.
I think there must be a retentive setting I'm meant to turn on for that tag so it holds? Or is something in the program putting 50 back over the top of it every scan, because I'm not sure where else to look?
Design tab or runtime tab when you watched it? And is that a Numeric Input Enable or a Numeric Input Cursor Point? If FactoryTalk Security is on, which user is the runtime logged in as, and has that user got write.
Runtime, on the panel itself. Numeric Input Enable. Default user, no security set up on that panel as far as I know. The other setpoints on the same screen hold fine, it's only Fill_SP_1 and Fill_SP_2 that revert.
> it's only Fill_SP_1 and Fill_SP_2 that revert
That's your tell. The panel writes fine, then something in the PLC writes it back. Right click Fill_SP_1, Cross Reference, and look for anything with it as a destination. MOV, CPS, COP into a structure it lives in. It'll be in there.
It's a routine called Init_Values, 12 rungs of MOV with no conditions on them at all. Source 50, dest Fill_SP_1. Fill_SP_2 is the rung under it. The other setpoints on the screen aren't in there.
Looks like somebody's starting values from when the line was built.
Right. A rung with no conditions runs every scan, so every 10ms or so that MOV puts 50 straight back. The panel wins for one scan and then loses.
Two ways to fix it. Put S:FS in front of every rung in Init_Values, that's the Logix first scan bit, so the MOVs only run on the first scan after a download or a power up. On a Siemens box you'd put the same MOVs in OB100 for the same effect. Or take the JSR to Init_Values out altogether, because Logix tags keep their value through a power cycle anyway and the routine's only any use right after a fresh download. I'd do the S:FS and leave it, less arguing.
Put S:FS in front of all 12 rungs and downloaded at the shift change. Setpoints hold now and the operators are happy.
For anyone searching this later, it was an Init_Values routine with unconditional MOVs putting 50 back into the setpoints every 10ms. S:FS on each rung and it only runs on first scan.
One of those 12 rungs was also moving 3000ms into a timer preset for the capper, which explains why nobody's ever been able to change that one either. That's a job for next week.
Thanks jcasey, and hannah for ruling out the panel side first.
Always a routine called Init_ something. Glad it wasn't the panel.