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Poll

Which PLC/IO form factor do you like best?

Modular
61 (59.8%)
Brick
25 (24.5%)
Stackable
13 (12.7%)
Other (please comment below)
3 (2.9%)

Total Members Voted: 72

Author Topic: Poll: PLC and I/O form factors...please vote!  (Read 59549 times)

BobO

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Poll: PLC and I/O form factors...please vote!
« on: June 11, 2008, 06:15:29 PM »
Hey ya'll, we were chatting about which is the best form factor for a PLC system. Clearly there is really no right or wrong answer, just opinions...however...would you help us out by telling us which you like (or use) the most? I used pretty broad catagories on purpose, but if there is one you think I should add, please PM me. Feel free to elaborate on your choice...or defend it...with a comment below. Discussions are good!

Thanks a bunch!
« Last Edit: June 13, 2008, 06:47:19 PM by BobO »
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

b_carlton

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Re: PLC and I/O form factors
« Reply #1 on: June 11, 2008, 07:04:33 PM »
As far as stackable - if I correctly understand the term - the AB CompactLogix/ML1500 I/O can be the most confusing expecially when mounted on DIN rail. The modules APPEAR to be connected but unless the electrical connection tab is flipped over properly, they aren't. Forgetting the termination end plate can be frustrating also.

All form factors have their advantages somewhere.
An output is a PLC's way of getting its inputs to change.

BobO

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Re: PLC and I/O form factors
« Reply #2 on: June 11, 2008, 07:14:14 PM »
Clearly they all have advantages...which is why they all exist...but I am trying to get a clue as to what our customers like best. Us product design engi-nerds have our own opinions...which while interesting, are substantially irrelevant. Folks that actually buy controls, on the other hand, have opinions that should be forcefully considered.

Actually Bernie, I'm trying to get a fight started...makes for lots of site activity. The next poll will involve politics. ;)
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

Controls Guy

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Re: PLC and I/O form factors
« Reply #3 on: June 11, 2008, 07:26:33 PM »
Looks like a three way tie, so you'll have to make at least one piece of each!  I **strongly** dislike stackables for reasons I've already outlined.  Completely modular ala DL205 is my favorite, but for small projects I certainly don't mind the expando-brick like the 06 or the early SLC's.

I like the idea of the a number of different slot-count bases, like the 205/305/405, etc.  The only advantage (other than potentially cost) to the stackables is finer granularity of I/O count vs. cubic and square inches of panel space, and if you have 4/6/8 slot bases, at worst only 1 empty slot is forced upon them except in extremely small jobs.  And don't forget, space for future expansion is generally considered an advantage, not a disadvantage.

I once had a guy from Grayhill trying to sell me on why it was good to use 1 or 2 point modules because you could build the machine with the exact I/O count.  (Even though their cost/point was enough higher that all the money saved went to Grayhill, not to me, and at the cost of shafting my customer.  They never seemed to notice that point.)  Then they came out with 16-point modules.  I asked (already knowing what answer I would get) why they thought 16-point modules would be a good idea.  He said that the the cost/point was enough lower that I could save money overall, even if it meant I had to ship machines with unused I/O points.  I asked him if this meant his competitors had had a superior product all along.

He said that no, low density modules were still superior to your high density ones, or AB's, due to their low point count, but that HIS multipoint ones had advantages over his low density ones, because of their higher point count.  I went for a shovel.
« Last Edit: June 11, 2008, 07:41:55 PM by Controls Guy »
I retract my earlier statement that half of all politicians are crooks.  Half of all politicians are NOT crooks.  There.

BobO

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Re: PLC and I/O form factors
« Reply #4 on: June 11, 2008, 10:21:05 PM »
Hmmm...have to think upon the dis-logic of the Grayhill chap. Methinks he may have gotten hold of some bad juju... ::)
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

ATU

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #5 on: June 17, 2008, 06:04:57 PM »
I selected all of the above because, you have to "make the shoe fit".  Application, price and size constraints choose which one to use.  My preference is a card based system, zip link type IO with expandable racks. I think it provides the most flexibility, highest reliability in the smallest space. Stackable systems are ok if you follow the rules.  With the CLX system, you have to careful about power supply sizing and  where it goes. Adding a module in the middle may not be so easy with the wiring. They sell a blank module to hold that space open, but if you are doing that, what's the advantage? The connectors can be a reliablility issue too. A long while ago, I used to use the Omron S6, which was stackable and it would really act funky sometimes if there was a poor connection in the module chain. Also it was tough to replace one in the middle. The CLX solves that, but as b_carlton stated, its not always easy to see when something is not properly connected.  With a rack system, it's usually pretty obvious if the card isn't seated and the power supplies increase with the rack size and you don't have to think about it most of the time. Also, The cost of a larger rack is usually minor. You only have to make sure to provide the space and for additional racks if required.  Bricks are great in their place, but blow one output and you have to replace it all. I think the 06 was a nice fit to take care of applications that are more than a brick, not quite justified for a rack based system, but provides some expansion at an affordable cost.
« Last Edit: June 17, 2008, 06:31:06 PM by ATU »

Controls Guy

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #6 on: June 17, 2008, 08:16:00 PM »
After reading your type by type critique, I still can't figure out the scenario when you would find a stackable the best choice.  All the stackable-specific comments seem to be negative.  If I'm reading you wrong, try explaining in smaller words and then I'll probably get it.   8)

And as far as bricks go, if you're using a brick with every last output used, you've already set yourself up for trouble in the first place, so no, that particular brick is not a good choice for that particular project.
« Last Edit: June 17, 2008, 09:42:55 PM by Controls Guy »
I retract my earlier statement that half of all politicians are crooks.  Half of all politicians are NOT crooks.  There.

BobO

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #7 on: June 17, 2008, 08:23:37 PM »
I selected all of the above because, you have to "make the shoe fit". 

I think that was the answer.

But what I also heard was...given the choice, he'd prefer modular...so in this context, I'd have to add an extra half vote to modular.
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

Controls Guy

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #8 on: June 17, 2008, 09:38:48 PM »
Well, he said "make the shoe fit" but failed to describe the foot that would be best fit by a stackable, only feet belonging to modulars and expando-bricks as I did.  Maybe you should rewrite the poll to allow votes for more than one type without voting for "all of the above".  It also occurred to me that this is exactly the type poll you might find in Control Design or Control Engineering to use as a proxy if you're having trouble getting a statistically significant sample, but I did a quick search and didn't turn any up.  Anyway, just my $0.000002 worth.

I hopped over to Control.com and didn't find any there either (didn't expect to, it's more of a Q&A forum), but I posted a thread asking for links to existing polls or failing that, for everyone to get over here and vote.
« Last Edit: June 17, 2008, 09:58:58 PM by Controls Guy »
I retract my earlier statement that half of all politicians are crooks.  Half of all politicians are NOT crooks.  There.

ATU

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #9 on: June 17, 2008, 10:29:49 PM »
Stackables make sense if the design is set in stone. Once the control package is produced, then it would never be altered. For instance, a standard piece of production machinery, ie. CNC, Molding, Stamping, PC board assembly, packaging etc.  Machines like this are highly competitive and proprietary. The end user would not have access to the program, so it would never be changed. If you want something different, you have to order it special from the factory and that would be a different model.  If you are a builder of this type of equipment then you want only exactly what is needed, spare slots are wasted space. The more compact the control panel is, the smaller the footprint which makes it more atractive. Floor space is money.

BobO

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #10 on: June 18, 2008, 12:15:58 AM »
Yeah, I guess I could change it to checkables. In truth, I wasn't looking for anything scientific...more just a general sense of how AD/Host customers feel about the problem. It is so easy to sit in our ivory towers (actually it's a 2 storey brick building on 50 acres of pasture in the foothills of the Smoky Mountains...not a tower in sight) and choose what people will like...or as they said at Siemens, 'vill like'. And it is equally easy to ask the marketing guys at AD what they think, and then drink the coolaid without question...and BTW, I like coolaid. However, I really want to balance my opinions and the opinions of AD with the opinions of our customers. Since I am stuck in the ivory tower...er, pasture...this forum is a great way to get a sanity check from actual users of our products.

So com'on...fight, argue, let the fur fly!! Express your opinions. We'll break into religion and politics shortly... ;D
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

BobO

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #11 on: June 18, 2008, 12:24:14 AM »
Ok...made the poll checkable...and removed 'all of the above', which kinda doesn't make sense with checkable. So if you 'all of the above' folks can re-vote...kinda like they do in Chicago...that'd be great.

Thanks!!
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

Controls Guy

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #12 on: June 18, 2008, 01:03:48 AM »
I tried to vote, but I got confused and voted for Buchanan. But my vote should still count, right?
I retract my earlier statement that half of all politicians are crooks.  Half of all politicians are NOT crooks.  There.

BobO

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #13 on: June 18, 2008, 01:06:36 AM »
Yes. For Buchanan. And don't even bring up that Chad guy... ;)
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

Controls Guy

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Re: Poll: PLC and I/O form factors...please vote!
« Reply #14 on: June 18, 2008, 01:18:20 AM »
I was working with a guy named Chad in Nov-Dec 2000 and we made sure he was always referred to as "Hanging Chad", "Swinging Chad", "Dimpled Chad" or best of all, "Pregnant Chad".
« Last Edit: June 18, 2008, 01:30:34 AM by Controls Guy »
I retract my earlier statement that half of all politicians are crooks.  Half of all politicians are NOT crooks.  There.