First pass

[Narlin]

Is there any RSLogix 500 instruction to tell a running processor that we need to start as if we had just powered up.

I need the 1st pass instructions to run after a power outage, even though a UPS kept the PLC from ever seeing the outage.
I can easily detect the outage as a certain combination of alarms all occurring at once, and the program has a whole set of 1st pass instructions that go around those alarms and get everything rolling again.

narlin

[dmroeder]

I believe it would be S:1/15

[Mickey]

If you can detect the power outage, then simply use the power coming back on to create a one-shot. Then put that in parallel with the first -pass instruction.

[MasterBlaster]

If I read the O/P correctly, he can detect loss of commercial power as a function of certain alarms activating. But restoration of power will certainly occur before those alarms can be cleared.

What I do is wire commercial power to a digital input, and use the state of that input to determine several things, one of which is to initiate "first scan" functions.

Bill

[Narlin]

masterblaster! That sounds like a plan. I will give it a try.
Thanks

narlin

[Lancie1]

Narlin,
For one system with emergency backup generator power (date on program 2005, how time flies!), I used a timer to deternmine if the power outage was serious enough to do an Emergency Shutdown. You easily change the Emerg Shutdown Relay to perform whatever functions you need to do if utility power is lost.