SLC 500 - Removing and Inserting Modules

[fredm54]

We had a bad OB16 module with a blown output transistor today. The SLC 500 rack has a 1746-P2 power supply and a 5/03 processor. One of my co-workers went to remove the bad OB16 and I reminded him he should turn off power to the SLC-500 rack first. He said "It's designed to be able to do that" I said, "I don't believe so" He said (with 100% assertiveness) "Yes you can"

So, as I watched I knew the CPU would have to fault and it did. When he replaced the OB16 (he actually put a OW16 relay output in) the power supply went out! He now thinks the power supply blew because he put the wrong module in. I told him it blew because you left the power on when you inserted the module.

We installed a new 1746 power supply and the correct OB16 and after using RSlogix to reset the fault (actually had to reload from eprom) all is ok now!

What I'm looking for and I searched the Rockwell Automation somewhat, is a PDF file or document number where it states whether or not power must be turned off when removing and inserting modules in a SLC-500 system.

Any thoughts?

thanks!

Fred

 

[Mickey]

You are right. You can do that with some controlLogix modules but not SLC500 modules. see PDF

 

[Operaghost]

Here is a link to the SLC 500 Modular Style User Manual. Look on page 103.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1747-um011_-en-p.pdf

OG

 

[Ken Roach]

You were right.

Because ControlLogix is so similar in size to SLC-500, I have seen other people assume they are the same backplane architecture.

Of course they're not; ControlLogix removal-and-insertion-under-power (RIUP) was a major nifty feature when the product line was introduced. SLC will always fault if you remove a module under power, and you have a high probability of damage if you insert a module under power.

A few years ago I watched an A-B product manager running on only a few hours of sleep pop an SLC-5/05 out of a running SLC rack on the Automation Fair show floor and illustrate something about the controller to a customer. I intercepted it before he could plug it back in, preventing both damage and embarassment.

Your co-worker gets style points for his assertion of a false premise.

 

[John Soltesz]

I think your co-worker needs a week of cleaning toilets and reading equipment manuals in his spare time.

We had one of electrical guys do the same thing with a 5/04. He only hosed the program. Then no one knew where the current program was. This dept has multiple laptops and of course multiple program versions. Yes it took 2 tries to get the correct version. Poor leadership in that dept. All that because they didn't pull a disconnect switch.

 

[fredm54]

Thank you so much for that information and link. I'll show it to my co-worker today and see what he says!

Fred

 

[brucechase]

Do you think his response will be "You were right and I was wrong", or do you think he will come up with some excuse and claim he's seen it done plenty of times?

From your first post it sounds like the latter. If so, I would definately use this as a learning experience about his knowledge and abilities. People like this can get you in trouble or even killed when dealing with electricity.

My 2 cents (and I'm sure it's worth much less than that)

 

[SLC_Integrator]

A good customer of ours learnt this the hard way.

They have a SLC5/05 that controls a pretty critical process. They wanted to use a ProSoft card that had been been installed in it some while ago but it was pinned RS323 instead of 485. Their guy popped the card out under power, changed the jumper and popped it back in. The CPU faulted and he couldnt get it to restart. They called us out at 8pm on a friday :angr: to see what was wrong.
In this case it toasted the CPU completely and we ended up replacing it, reloading the program and setting up his Prosoft.

Lesson learnt I guess.

 

[dmroeder]

Do you think his response will be "You were right and I was wrong", or do you think he will come up with some excuse and claim he's seen it done plenty of times?

From your first post it sounds like the latter.

I've worked with one of them. Typically, you can't convince them and they always have an answer.

 

[fredm54]

He read the information and he agreed it's always better to power off before removing or inserting modules. BUT, he swears he read it somewhere, got some training years ago where he heard that these new SLCs support removing and inserting with power!!!

He proceeded to go thru our manuals looking for something but all he found was what just what you all have said. BUT, he still thinks plugging in a OW16 instead of an OB16 was the thing that fried the power supply. YIKES!!!

Anyway, I think he learned his lesson and I don't think he'll do that again!

Fred

 

[TConnolly]

Thanks for the update.

...these new SLCs support removing and inserting with power!!!

NEW SLCs?

Theres a big clue right there. I bet that your cow-orker is confusing the SLC with the ControlLogix. In the CLX you can insert and remove under power, but the backplane architecture is completely different.

 

[fredm54]

He meant WHEN the SLC was fairly new.

Just when did AB introduce the SLC line?

Back in 1982 we installed 2 Allen Bradley PLCs. Just that: P L C !!! These used core memory (Three 4k core memory boards for 12k of ram for each PLC) We had a dedicated AB terminal attached for monitoring. Then in 1984 or 85 we installed about 8 PLC-2's.

All that is gone now, we now have about 60-65 SLC-500's using 5/02, 5/03 and 5/04 CPUs. About a dozen PLC-5's. No ControlLogix at all. Also have 45 CPM and DCM cards in most of all those SLC racks. All other modules are pretty standard I/O stuff.

thanks again!

Fred

 

[fredm54]

Oh, I mentioned Control Logix and got the "Deer in the headlights" look !!!

Now I have heard of Control Logix but never saw one in person.

Fred

 

[TConnolly]

Think of a new chrome Harley Electra Glide -vs- 25 year old kick start Yamaha 125 with a bent foot peg.

 

[curlyandshemp]

Think of a new chrome Harley Electra Glide -vs- 25 year old kick start Yamaha 125 with a bent foot peg.

ooooh, shiny black and chrome?