I/O System Recommendations

dmargineau said:

A Point I/O 'Rack' could contain up to 99 modules (792 I/O) which can be 'split' in up to 5 banks using Expansion Power Modules (1734-EP24DC) and 3 or 9 foot Expansion Cables (1734-EXT1-3); several adjacent enclosures should be able to mitigate any cabling/wiring installation issues.

Click to expand...

I thought the limit was 63 digital IO modules, less if you add analogs...?

Yes you are correct; no more than 63 modules of any type.
The AB Architecture Builder will 'let' you add 99 PIO sockets, however, will allow only 63 modules to be 'inserted'; again, Analog modules will not alter the maximum permitted modules count.

There is a caveat if there is more than one device that needs to talk to the rack with analog and other specialty modules, George can explain it better than I can... http://www.plctalk.net/qanda/showpost.php?p=618700&postcount=6

tl;dr...

My personal 'record' is 53 Point I/O modules within a Remote Rack...45 Digital and 8 Analog...It's been smoothly running 24/7/365 for almost five years...L72 controller-EN2T EIP bridge.

I have also seen 63 modules PIO racks, some fully digital, some mixed, digital, analog or HSC...

If you need to cram the most I/O within a given 'space' you cannot beat Point I/O...Yes there were hardware issues when the 1734 line came out, however, haven't heard of any lately...And a 1734-AENT costs less than $400...You could always add another EIP node at minimum costs.

Thanks all for the suggestions/advice.

Some further testing revealed that the valves are not AS-I ready, so I am leaning towards a discrete I/O solution. It is possible that we will replace the valve head and controls, depending on if the how many valves' current electronics are functional, at which point I'll revisit the AS-I option. I do personally think this would be the cleanest solution with the least wiring. Fortunately, the complexity of the install was not lost on management, so I have some additional planning time for the project.

That said, for the discrete I/O I am leaning towards POINT for the following reasons informed by the info provided here:
-Compatibility with 1756
-Personal familiarity
-Uniformity with the rest of the facility
-Smaller footprint than compact i/o
-Lower cost
-I have settled on using POINT IO for the tanks

I will need 90 modules total, not including spares. I have not used the extension cables before, and have some questions. I tried looking it up for myself, but the only description I found was on page 49 of the selection guide.

-Even with the cable, the module limit for one AENTR is 63 modules?
-The cable only serves as a means of organizing, it does not change the functionality, correct? E.g. 40 modules on one AENTR is equivalent to 20 modules on an AENTR with another 20 on the extension cable?
-Are the power requirements different due to the cable run, or am I overthinking this?

I will do some rack length calculations today. We have a 60" by 36" enclosure that we would like to use for this, but cramming all the wiring into one space might be the limiting factor here. Perhaps multiple panels as others suggested will be necessary.

Dryhops said:

-Even with the cable, the module limit for one AENTR is 63 modules?

Click to expand...

Yes, Point I/O 'racks' support a maximum of 63 modules.

Dryhops said:

-The cable only serves as a means of organizing, it does not change the functionality, correct? E.g. 40 modules on one AENTR is equivalent to 20 modules on an AENTR with another 20 on the extension cable?

Click to expand...

That is correct; you could start another PIO 'row' or continue into another enclosure without modifying any configuration and/or functionality.

Dryhops said:

-Are the power requirements different due to the cable run, or am I overthinking this?

Click to expand...

No you are not; bus and device power requirements are very important; some modules need less and some need more supply current and/or different voltages.

I find the RA Integrate Architecture Builder (IAB) utility tool very useful when designing any Logix system; you could build your Point I/O 'Rack' with one or up to five 'banks' of PIO sockets and then start adding I/O modules; the utility will automatically add the required 1734-EP24V DC power expansion modules depending of the number and type of the preceding I/O and/or the eventual 1734-EXT1(3) extension cables presence or their lengths.

https://www.rockwellautomation.com/global/support/product-selection-configuration/overview.page

https://www.youtube.com/watch?v=-VWWYH0S0HY

I know you have chosen point (which is a good choice), but just to throw this in the mix...

on my current project I am using SMC (pneumatics) EX600 bank, the SI (e/ip) sits in the middle with the pneumatic valves on the right, and on the left I have several 8x M8 3-pin digital in's and 2 x M12 analog in's... saves a lot of wiring just use pre-made sensor cables. One power cable (4 wire, 2 x bus power and 2 x safety dropped voltage), One ethernet cable.