Cold starts

Hi,

I'm trying to figure out the cold start parameters my compactlogix controller is using. Where do I find this in RSlogix5000?

Thank you!

personally, I'm not sure what you mean by "cold start parameters" ...

please give us some more information about what you're trying to accomplish ...

I'm just guessing here - but maybe you're interested in how the processor starts up in a "go to run" situation ... example: the power was OFF - the processor was shut down - the power comes back ON - the processor goes into the RUN mode ...

which leads to your question: "how does the program react?" ...

am I even close? ...

I guess he´s referring to data used or manipulated when first scan bit is set.

Yeah, I want to better understand what happens if control power is lost. I know they have a battery in the processor that holds the states of the memory. Isn't the first scan bit just the first rung of your program main?

The 'First Scan' is ON all the way through the first regular scan of the logic.

But there is also a 'pre-scan' which happens between turn-on and the first scan mentioned above. Most of the instructions, in their 'help' explanations, define what happens during the 'pre-scan'. One item to note is that locations targeted by an OTE instruction will be turned OFF during the pre-scan. But items referenced only by OTL/OTU instructions retain their condition from the power down state.

There is also a 'power up' routine which has nothing in it by default which can be used.

Where is this "power up" routine? I do not see it?

Isn't the first scan bit just the first rung of your program main?

Click to expand...

with the ControlLogix and CompactLogix platforms it can get a LOT more complex than that ...

the "first scan" bit that you obviously have in mind is addressed as S:FS in the RSLogix5000 software ...

basically it will have a status of ONE for only the FIRST PASS that its PROGRAM gets scanned ... so far – no issues ... in simplest terms, an XIC addressed to S:FS will be TRUE on the first pass that its PROGRAM gets scanned ...

but ... (this gets tricky) in a CompactLogix system, the PROGRAM may (or may NOT) get scanned as soon as the processor first goes into the RUN mode ...

(this gets even trickier) ...

you can have MANY bits with the address S:FS – and they can all "fire" at DIFFERENT times ...

I'm betting that you've previously worked with RSLogix500 or RSLogix5 software – in which there is only ONE "first pass" bit ... that would be S:1/15 ... (ah, the good-old days) ...

but ...

in the "new and improved" RSLogix5000 software each PROGRAM can have its very own S:FS bit – and due to the way various PROGRAMS can be SCHEDULED for scanning by various TASKS, then each PROGRAM's "first scan" bit could be scanned at varying times ...

secret handshake: the word PROGRAM in RSLogix5000 doesn't mean the same thing as the same word PROGRAM in RSLogix5 or RSLogix500 ... in RSLogix5000 you can have MANY different "programs" within your one "application/project" ...

that's a fundamental difference in the older platforms and the newer RSLogix5000-type platforms ...

is that enough to answer your question – or do you need more detail to get started? ...

TIP: if you're asking this type of question for a specific reason, then you should also read up on PRESCAN and how it affects the systems that you're working with ...