Track Changes to Rslogixs Plc Progran?

MountainGoat

Member
Location
Utah
Occupation
Process Engineer
Need to see exactly where the guys on days are making changes to Plc programs because they never let anyone know what they done and leave issues to be fixed and waiting.

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ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
Fire one or two of them.
Keep backup copies. My days of programming are getting more distant but backups were automatically generated at set intervals IIRC. Even for the small projects I did, looking back was a pain. Do you have a Compare utility that lists the differences?
 

MountainGoat

Member
Location
Utah
Occupation
Process Engineer
We have Rslogic compare tool. I was looking around for the counter I usually fix when the company software doesn't update counts on the displays via data concentrator......

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tom baker

First Chief Moderator
Staff member
Rockwell makes a program that keeps track of changes, designed for just the situation you describe.
I believe this works best in a server enviroment
f you are using RSLogix 5000 you can do an upload and get the most current. RSLogix 500 you have to keep the off line version to get all the edit comments.
W
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I find it offensive that people make seemingly random changes to my programs that don't actually fix anything.

Often they seem to be made so that instead of fixing something simple (like a bad limit switch) they can just make the system limp along without it.

Get about 5 or 10 of those kind of changes to a typical program and often it won't run at all after a while.

I get that production is important but at some point fixing the actual problem ought to be something that someone takes seriously.

The other thing I hate is changes made to the sequence of operation in the dead of night without any clue as to how it might affect other things. I have had interlocks taken out with other pieces of equipment and then there are collisions that somehow are a software problem. It is not a software problem. It is a third shift electrician problem.

And no one bothers to put a comment in there explaining who did what and why. Makes me crazy. I always try to put a dated comment with my initials in when I change something on a system that has been running. That way people looking at it can see who changed it and why. The midnight program editors never seem to do that. it is a mystery as to who or why.
 

paulengr

Senior Member
Rockwell makes a program that keeps track of changes, designed for just the situation you describe.
I believe this works best in a server enviroment
f you are using RSLogix 5000 you can do an upload and get the most current. RSLogix 500 you have to keep the off line version to get all the edit comments.
W
It only works if you work through the modified version of RS-Linx which means removing the regular version off every laptop. Actually RS-Linx IS the security system. Just one serial cable and a direct link to the processor and your security is almost totally bypassed.

You can pay though for automatic backup in the same software. The server goes out checking every processor and makes automatic backups. Doesn’t stop it but it does track the changes. And you can do a one click revert to the original program.

I’m all for just issuing maintenance versions of RS Logix. You can look, you may or may not do forces, even variable edits are OK. But no rung editing allowed. And the licenses are roughly equal to about 10 copies for one copy of the programmer versions. Let’s maintenance do their jobs.

The issue here is the same as changing overloads and fuses, installing jumpers and bypasses, and all kinds of creative hacks. For testing and troubleshooting software and hardware bypasses are not only useful but often a necessity. The problem comes in that when the job is “done”, all the bypasses must be removed. But it’s so easy to bypass say a faulty safety that it becomes permanent. Then it becomes routine practice pretty quickly. The only way to change the behavior is to treat it like a LOTO violation. It’s just another form of cutting corners and leads to equipment damage and eventually someone is injured or killed.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Things that are actual safety issues should never be handled in software that can be readily changed.

Issues of damage to the machine are not safety problems, although they are often treated like they are.
 

paulengr

Senior Member
Things that are actual safety issues should never be handled in software that can be readily changed.

Issues of damage to the machine are not safety problems, although they are often treated like they are.
So tell me the difference between a software and a hardware jumper? If I jumper out an interlock, does it matter what the mechanism is?

And to your point does it matter if it it is an input to a PLC or a hard wired series connection?

I would argue there is a huge difference. When PLCs replaced relay logic reliability took a massive leap forward, like an order of magnitude. Arguing software vs. hardware is stupid. The difference in reliability is proven. In a PLC circuit typically every interlock involves just three parts: power source, interlock sensor, and PLC input. Every input is independent. I don’t have to sort through a half dozen series devices, never mind trying to catch things “in the act” in the relays. I can right click and create a trend chart in anything. And I can troubleshoot every input independently. And issues with loose wires and failing contacts don’t cause intermittent problems with a half dozen other devices.

Otherwise we would never have used PLCs. And to go a step further a standard high quality PLC can be used for SIL 2, and so-called safety PLCs with safety inputs and outputs (no single points if failure) achieve SIL 3. It is possible but highly impractical to build a SIL 3 system never mind SIL 2 in relay hardware.

Abs with all that being said, you can bypass your relay system for $8.99 on Amazon.


Never mind tricks with cardboard, coat hangers, and string. And those safety inputs have some evil tricks that make jumpers fail.

The issue with PLCs is that it is very easy to write very poor code. It is very easy to make it almost unreadable. PLC programmers don’t typically get formal training on good programming practices and professional programmers don’t understand ladder logic. And they don’t get trained in things like Mealy-Moore logic and state transition vs. level based logic. So no training in race conditions or logic hazards. So PLC programmers often don’t understand why their code turns into race conditions, logic hazards, or why it is difficult to “reset” or crashes when an input becomes intermittent. Of all things this kind of training is only routinely taught in classes on digital logic for building digital electronics. Good code is very obvious, easy to read, and largely if not entirely race condition and logic hazard free.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
It is not easy to bypass actual safety functions in a safety plc.

Typical interlocks on a plc or any control system are not safety functions. They protect the machine or the product. Safety functions protect people and should not be readily bypassed. If they can be readily bypassed pretty much by definition they are not safety functions.
 
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