correct I/O Installation

exiled · Oct 31, 2006

Hi guys
what is the correct way to install cards into a rack.
ie
i have a SLC503cpu, 1746-OB16, 1746-OW16, 1746-NI4, 1746-NI8, 1746-IM16, 2X 1746-ITB16
Do i put the analogues first then the outputs or inputs before eveything.
the above is Bradley example we also have mitsubishi and omron (****)
I have heard different stories off different sparkies/engineers

thanks

Ken Moore · Oct 31, 2006

Doesn't really matter as long as you use good wiring/grounding practices, and use shielded cable for the analogs.
I try to group like modules together, all the AC discrete, then the DC discrete, and finally the analog modules.

Doug_Adam · Oct 31, 2006

With some PLCs, you can only put special types of cards in certain positions on the racks.
For example, many PLCs have the rule that interrupt cards must be placed in the same rack as the CPU.
For many PLCs, it does not matter. You have to check the manual for each PLC and each type of card.

On the other hand, for neatness people usually like to line up all the cards of one type, so you may get, for example, Comms Cards, Specials, Analogue inputs, Analogue outputs, Digital inputs then Digital outputs in that order.

Ken Roach · Oct 31, 2006

For the SLC-500 series of controllers, there is no restriction on what type of module may be placed in each slot of the controller chassis.

Of course, only the CPU fits in the left-most slot.

When a Remote I/O adapter (1747-ASB or 1747-ACNR) is used, data management and compatibility get more complex. But with ordinary 4, 7, 10 or 13 slot chassis (up to 30 slots with interconnected chassis) there is no logical restriction.

I agree that most users separate by voltage or signal type, but that is their choice and not dictated by the chassis.

scottmurphy · Nov 1, 2006

Depending on your IO requirements, we sometimes set up DOL or Valve groups, ie. Slot 1 = DO, slot 2 = DI ( DOL Group )
Slot 3 = DO, slot 4 = DI, slot 5 = DI ( Valve Group ), this makes fault routines tidier and easier, and also coding ( in the bit world ( non CLX ) of addressing )

It can be preference as well, depends how tidy and structured you want to be, and of course, how much IO you have to play with.

ChuckM · Nov 1, 2006

Years ago we were told by the Omron didributer that we bought from to put analog cards closest to the CPU, then discreet inputs and the outputs. Now that we use A/B we still do that even though it isn't necessary (and I doubt it was back then).

I did play with an Automation Direct unit a while back and thought there were some specs on layout but I don't really recall.

memberpeace · Nov 1, 2006

I used to work as a contractor. I saw all sorts of installations in different plants. So there is not any rule for it.

For my opinion I think electrically it is better to install the units at the beginning (1,2,..) which take bigger current. You can have that current figures from their catalogs, paper work.

gphillips · Nov 1, 2006

It looks like I might be alone but I always put discrete inputs in first, then analog inputs, then outputs. That way when I look at my i/o legend the i's are on the left and the o's on the right. Guess I could do it backwards and make an o/i legend.

hd_coop · Nov 1, 2006

I'm currently working on my first ControlNet project, is there any truth to this (from the ControlNet Adapter User Manual):

To optimize ControlNet network bandwidth, place the

devices in the following order (left to right on the chassis):

· 1747-ACNR15 adapter

· Discrete input modules

· Discrete output modules

· Any intelligent and/or analog I/O modules that you want

to establish individual module connections to

Freak · Nov 2, 2006

I do it like gphillips, doesn't really matter but it makes sense to me. Remeber if you have spare slot's on the rack to leave a spare between different types of cards if possible, otherwise it will get messy later.

correct I/O Installation

exiled

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Freak

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