Question on upgrading system

[Bendanator 0]

Hello everyone,

 

I have a question on a upgrade we had done at our factory. We had a older slc 500 running and pvc power transfer system and was asked to upgrade. I recommend a compact logix plc to replace but somewhere along the line I was out voted(not saying that was the wrong move at all just need more knowledge on the topic). Instead they installed a compact logix processor to the older slc still using the slc plc? If pricing was not a concern would it have been better to just remove the slc altogether? I know we use 1746-ow16 cards and wondering how long this system will be serviced by Allen Bradley or was using the slc a good move? Thanks for all the knowledge in advance!👍🏻

[Michael Lloyd 85]

Whatever answer you get here will be right. Ie it's just an opinion.

Personally... I would have just installed a complete CLX box. BUT... I don't know anything about your system.

Things like - how long can you be down for cutover? How much IO is there? - play into the discussion. If downtime is a problem then wiring in a new rack full of cards may be prohibitive.

Relay output cards have a finite number of cycles, at some point individual points start to fail. Depending on the service of the card(s) (cyclic vs non-cyclic) that could be a factor in the decision to do the upgrade. If it's a low cycle installation then they are probably fine (or not :) ). One thing that nobody considers is the longevity of the components on individual cards. Electrolytic and Tantalum capacitor have a service lifespan specification (typically no more than 10,000 hours max but higher is sometimes available for a cost). 10,000 hours is not very long. If the equipment is in operation 24/7 10,000 hours is a little over a year. I think most people think of electronic devices as either disposable or eternal. I prefer think of them as repairable or about to fail :)  

I'd have swapped the entire rack and card assembly...

[pcmccartney1 141]

Remember, it is all about who's budget the monies comes out of, maintenance or capitol expenditures.  Questions regarding how long you want to extend the life cycle of the machine or process are a factor.

I've done upgrades with CLX where we would put a 1734-AENT in the spot of the SLC, simplifies conversion effort and reduces rewiring.

Given sufficient budget, I would have completely eliminated the SLC and it's IO Rack.  Obsolescence of the SLC, rack and io modules will eventually force full upgrade.