AB PLC5 Upgrade to Control Logix

[delta_nsw]

We have a client who wants to upgrade from a PLC5 installation to Control Logix. They have four 5/80E processors with about 6 to 8 remote racks per processor each rack has about 16 cards (common digital and analog I/O) in it. I think that the best alternative would be to replace the 5/80E with Control Logix, keep the existing I/O racks and link to these racks via the existing Remote I/O links (add one to replace the processor). I know that technically this is possible but I would like to find out what potential pitfalls or drawbacks there may be. The I/O is all in good shape, and is made up of commonly available cards.

 

[JaxGTO]

I would push to replace the IO. Even tho is simple IO you still cant get them anymore.
And what ever you do, don't use that conversion cables and IO, it's junk, and you still have to use the original swing arms.
Best to just bit the bullet and do it right IMO.

 

[delta_nsw]

I would push to replace the IO. Even tho is simple IO you still cant get them anymore.
And what ever you do, don't use that conversion cables and IO, it's junk, and you still have to use the original swing arms.
Best to just bit the bullet and do it right IMO.

Thanks for the response. It is good to get some feedback on the conversion cables. My thoughts are, that the installed I/O cards are all pretty standard and robust, spares to last 50 years can be bought via a surplus dealer or eBay for a small cost.

 

[delta_nsw]

Thanks for the response. It is good to get some feedback on the conversion cables. My thoughts are, that the installed I/O cards are all pretty standard and robust, spares to last 50 years can be bought via a surplus dealer or eBay for a small cost.

Certainly, the conversion cable sounds like it could be a problem since it would replace 1 connection (swing arm to card) with 3.

 

[Fyfey96]

You could use AB's Integrated Architecture Builder Software to build the system and it will show you an upgrade path recommendation with BOM and costs.

 

[Aardwizz]

For a "quick and dirty" solution, you can buy a new CLX process and a DHRIO card, put the PLC-5s into "Scanner Mode" (effectively turning them into ASBs), run the conversion tool, and you're up and running.

Or walking, at any rate.

The system wouldn't be easy to work with / troubleshoot. And the aging 1771 hardware could be problematic. But if uptime is important, this gets you started to modernize with minimal effort. And if something isn't right in the conversion, you can easily revert to the existing system since no wires have be cut and all the pieces are still in place.

Later, you can update the code to get rid of all of the N7[0] and B3[0] addressing giving them real tag names, and rack-by-rack, replace the 1771 I/O with your preferred style of I/O (Point, Flex, or CLX).

This may wind up costing more in the end, but the risks are less and downtimes more manageable / coordinated with routine PM shutdowns.

It's an idea. {Note the lack of adjectives: "good", "bad", "clever", "crazy", etc. Akin to the adject-free phase "Sounds like a plan"}

 

[Keystone]

You could try a staged approach. We did this with some of our large complex pieces of equipment when we did a conversion. I am glad we did it this way! On one conversion we had to revert back to the PLC-5, take a step back, fix somethings and do it again. We only had the machine down for an extra hour. While I was then able to calmly address the issues over the next two days while the machine calmly ran on the old PLC5 for another week till we converted to the CLX processor again and everything took right off.


Similar to what Aardwizz suggested:

Stage 1:
Convert the program and -use alias- for the I/O from the RIO racks.
Get rid of N7 and B3.
Remap the HMIs to the new alias names and converted N7 and B3s - this way you will not have to make changes in Stage 2 to the HMI.
Use a CLX processor and DHRIO card and ENet card for comms and HMIs.
Replace the processor with a ASB card and treat the PLC5 rack as another remote I/O rack.

Stage 2:
Remap the aliases to the new CLX rack address (using an Ethernet card in slot 17)
Use the AB 1771 to CLX rack adapter solution - cost money but a lot less rewire time and less trouble shooting.
Replace any RIO peripherals (HMI, Scale Controllers, etc) to IP based solutions.

Yes, like Aardwizz said, there is more programming and intermediate work involved but with such a large system it gives you the change to "revert" back to PLC-5 if you find major issues with your converted program. It gives you a fail safe, but cost you more time. It could avoid uncomfortable "it should have worked" conversations after you landed all those wires to new CLX IO and find some major problems and have no recourse but to push on and loose sleep and have angry customers.

You can always give both options to your client and see if they want to safe or cheep.

 

[arpus4KM]

Thanks for the response. It is good to get some feedback on the conversion cables. My thoughts are, that the installed I/O cards are all pretty standard and robust, spares to last 50 years can be bought via a surplus dealer or eBay for a small cost.

I'm usually pretty on board with not changing things unless necessary, and the PLC5 are very robust.

but you are talking things that could be as old as 1986. by the time 40 more years pass you are looking at 70+ year old electronics.... It was time to swap it a while ago, if not for the sake of staying closer to todays standards, then for that fact that the hardware will be good to go in 25 years, but the people working on it are going to be completely out of touch with how the old hardware was configured and used.

 

[robertmee]

Swap them...Do not rely on PLC5 I/O. The IC chips in every one of them have a finite lifetime. 40 years, youre on borrowed time. You can buy parts on eBay, sure, but they have the same 40 year old chips in them, and are subject to random failures that will drive technicians crazy.

 

[Corsair]

I have a friend that worked for a supplier of custom power supplies for the military. One of the issues was a long required shelf life - accounting for capacitor aging. It varies with the type and quality of the capacitor. I suspect this is especially true with linear supplies.

When we used to use the old Symax stuff a friend told me that if you had intermittent problems change out the supply - he was frequently right. The same thing is often true with today's laptops.

The I/O cards may not have large electrolytics - but the supplies are another thing.

Get the old stuff out of there ASAP.

 

[Ken Roach]

I agree with Keystone that staged migrations bring you the least risk of downtime, at the expense of engineering time.

My experience with 1756-DHRIO modules has been mixed. If you have more than about sixteen block transfer devices in the system, you're probably going to have to do some buffer management which is a pain. Better to use an AN-X4-ABRIO bridge module as the Scanner for the RIO, and connect to it from the ControlLogix.

Those bridges (built by QTS in Florida, sold and supported by Prosoft worldwide) also give you some more flexibility and opportunity. I think they still support "ghost mode" where you can use them to listen in on RIO traffic, so you can run your ControlLogix code in parallel with the PLC-5 and compare the outputs.

The 1771 to 1756 conversion swingarms are really pretty good, and RA has had a long time to get the kinks out. I wouldn't do conversion swingarms attempting any other kind of I/O platform: I'd re-wire everything.

 

[lmscar12]

My experience with 1756-DHRIO modules has been mixed. If you have more than about sixteen block transfer devices in the system, you're probably going to have to do some buffer management which is a pain. Better to use an AN-X4-ABRIO bridge module as the Scanner for the RIO, and connect to it from the ControlLogix.

Keep in mind that there's a difference between 1756-DHRIO and 1756-RIO modules too. The 1756-RIO is purpose built for remote I/O and does the BTW/BTRs natively rather than requiring the PLC to do it. Every time I've done blue hose remote I/O on ControlLogix, I've done it with the RIO card, not the DHRIO card. Biggest project was 8 racks of PLC5 I/O, with no issues.

 

[jstolaruk]

If a decision is made to use the existing I/O with the 1756-RIO or 1756-DHRIO, have a plan in place to swap the I/O to new stuff, at least incrementally. Those 2 modules are end-of-life and will be discontinued at the end of the year 2025 and 2024. ( Ken's recommendation to use the Prosoft Gateway is the best choice ).

 

[delta_nsw]

I'm usually pretty on board with not changing things unless necessary, and the PLC5 are very robust.

but you are talking things that could be as old as 1986. by the time 40 more years pass you are looking at 70+ year old electronics.... It was time to swap it a while ago, if not for the sake of staying closer to todays standards, then for that fact that the hardware will be good to go in 25 years, but the people working on it are going to be completely out of touch with how the old hardware was configured and used.

The hardware was installed around 1998 I am not too sure how long they expect to run it but it would probably be more like 10-20 years. The I/O are all common cards and in good shape.

 

[BobB]

I am looking at replacing an old SLC500 system on a generator system in a data centre. Cost id frightening!!!!! And AB cannot guarantee that it will rok. Be careful. There is Modbus, CAN you name it. Looking very painful!!!!