Logix5000 CIP

daba · Nov 27, 2016

Does anyone know how I can programmatically disable forces in a Logix5000 controller.

I have a client who believes that forcing is the devil's work, and wants it killed instantly.

I am assuming it might be done via a CIP message to self, because the programming software can do it.

Operaghost · Nov 27, 2016

I've used the GSV to detect forces and to turn on a bit when it happens. But, I had asked one of the product guys a few years back if there was a way to do something like what you are asking. He had said that while it was probably possible, they had not exposed the necessary pieces internally to make it work. Maybe that has changed since then and someone can fill us both in.

OG

Archie · Nov 27, 2016

Try a generic CIP message using service code 4e, class 69, instance 0

Triggering that MSG instruction will remove all forces. I have only tested it on V24, so I can't guarantee it will work on other versions.

daba · Nov 28, 2016

Archie said:
Try a generic CIP message using service code 4e, class 69, instance 0

Triggering that MSG instruction will remove all forces. I have only tested it on V24, so I can't guarantee it will work on other versions.

That is excellent Archie, works a treat ... thanks very much.

ASF · Nov 28, 2016

That's a neat trick...thanks Archie!

daba said:
I have a client who believes that forcing is the devil's work, and wants it killed instantly.

Side note: all I could think of when I read that was this...

robertmee · Nov 28, 2016

^ Forcing, foosball and facebook....all the devils to me.

daba · Nov 29, 2016

daba said:
That is excellent Archie, works a treat ... thanks very much.

Just need to find a way to kill SFC forces as well.....

Archie · Nov 29, 2016

daba said:
Just need to find a way to kill SFC forces as well.....

Very similar, except using class 0x68

daba · Nov 29, 2016

Archie said:
Very similar, except using class 0x68

Thanks Archie - where are you getting these from ? Is there a publication ?

Archie · Nov 29, 2016

daba said:
Thanks Archie - where are you getting these from ? Is there a publication ?

I have a lot of it in my notes from years of reverse engineering. Very little is publicly documented. I decided to start publishing it as people ask for it:

http://advancedhmi.com/documentation/index.php?title=Class_Codes_for_ControlLogix

daba · Nov 29, 2016

Archie said:
.. Very little is publicly documented....

It does seem odd that something as fundamental as ensuring forces cannot be applied isn't included in the sparse documentation. Everything must be "get-at-able", because the programming software can do it, so why aren't we allowed the information to "undo" anything that a tired and unwary maint. tech. might do inadvertantly.

I would have thought that "regulated" industries would absolutely require that functionality.

Archie · Nov 29, 2016

daba said:
It does seem odd that something as fundamental as ensuring forces cannot be applied isn't included in the sparse documentation. Everything must be "get-at-able", because the programming software can do it, so why aren't we allowed the information to "undo" anything that a tired and unwary maint. tech. might do inadvertantly.

I would have thought that "regulated" industries would absolutely require that functionality.

AB seems to be quite secretive about many details of their software and hardware. I'm not sure if they are trying to protect things by only allowing them to make software with these capabilities or if they consider some of these things a security risk. If you really think about it, a hacker or disgruntled employee could really do some major damage to a company if they knew how to do some of these things, especially if all of their machines are networked together.

daba · Nov 29, 2016

Archie said:
..........If you really think about it, a hacker or disgruntled employee could really do some major damage to a company if they knew how to do some of these things, especially if all of their machines are networked together.

We are talking about the sort of things that can be done by RSLogix/Studio5000... something a hacker or disgruntled employee could get easy access to.

Perhaps they think that holding back these "under-the-hood" details will help them sell hundreds of licenses for AssetCentre, but that doesn't protect from hackers or disgruntled employees.

If I were a disgruntled employee, I could put code in my PLC to overwrite I/O tag values in all the PLCs on the network, that would cause huge problems, but I can't disable forces before they take effect .... go figure....

JasonTheSparky · Dec 3, 2016

Very interesting....Archie, is it possible to trigger a bit if someone is online with a processor? Specifically, start a routine if someone is connected?

Archie · Dec 3, 2016

JasonTheSparky said:
Very interesting....Archie, is it possible to trigger a bit if someone is online with a processor? Specifically, start a routine if someone is connected?

I haven't found any way of doing that yet. I thought maybe looking at the instance count on the connection object, but the attribute seems to be inaccessible.

Logix5000 CIP

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