Control Logix no more RIO?

We are looking at replacing a PLC5/40E system that has 3 remote I/O racks, in separate MCC's, with a Control Logix setup. All chassis, currently with Remote I/O ASB adapters, will be replaced with Control Logix.

My distributor is telling me that we will have to move away from the existing blue hose, as RIO is not used in Control Logix. I find that hard to believe? AB offers 1756-RIO and DHRIO modules. They seem like current offerings.

Are these modules only for migration purposes? ie mixed PLC5 I/O with a CLX processor?

Regardless, is there a compelling reason to move away from RIO anyways?

cncsparky said:

We are looking at replacing a PLC5/40E system that has 3 remote I/O racks, in separate MCC's, with a Control Logix setup. All chassis, currently with Remote I/O ASB adapters, will be replaced with Control Logix.

My distributor is telling me that we will have to move away from the existing blue hose, as RIO is not used in Control Logix. I find that hard to believe? AB offers 1756-RIO and DHRIO modules. They seem like current offerings.

Click to expand...

I think your distributor is right. Now if you wanted to keep the 1771 I/O and control it with RIO, you could do that with the aforementioned modules. But the RIO protocol can't support Logix5k I/O data, so if you use 1756 I/O in the remotes, you need a different network media and protocol.

cncsparky said:

Regardless, is there a compelling reason to move away from RIO anyways?

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Only because the hardware that uses it is going bye-bye. I like RIO and DH+; it is simple and robust, but it is going to be hard to get replacement modules in the future.

What sort of cable lengths are you dealing with?

Thanks Okie,

OkiePC said:

But the RIO protocol can't support Logix5k I/O data, so if you use 1756 I/O in the remotes, you need a different network media and protocol.

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http://www.ab.com/en/epub/catalogs/...ata-Highway-Plus-and-Remote-I-O-Networks.html

I don't see anything here that indicates RIO doesn't work with control logix remote chassis. Looks like the opposite based on the graphic at the bottom of the page. Where could I find more info?

May give Tech Connect a call tomorrow.

Even if you can do RIO to a remote CLX chassis why on earth would you do that? CLX doesn't have native btw/btw instructions you have to mimic those using MSG instructions.

The compelling reason to move away from It is so 10 - 15 years from now someone doesn't question your sanity or your companies frugal spending. Also will anyone be left with knowledge to support it?

Contrologix Plc to contrologix remote racks over RIO is not a supported solution and will not work for several reasons.

Why would you want to do that anyway? If you are replacing all the IO the only thing left is to change the media from RIO to Ethernet or ControlNet.

Even if it would work it would be just plain stupid. Replacing the media is the easy part.

cncsparky said:

Thanks Okie,



http://www.ab.com/en/epub/catalogs/...ata-Highway-Plus-and-Remote-I-O-Networks.html

I don't see anything here that indicates RIO doesn't work with control logix remote chassis. Looks like the opposite based on the graphic at the bottom of the page. Where could I find more info?

May give Tech Connect a call tomorrow.

Click to expand...

Well, maybe you can use the 1756-RIO as an adapter. I am not familiar with that module. I would still lean toward a more modern network unless there is a compelling reason to keep the blue hose.

Good eye on that diagram, but it's just showing that the 1756-RIO does have an Adapter Mode. You must have a CPU in the chassis to make use of it, and it's a very uncommon use of the module.

I've been answering this question since 1997. You can't use 1756 series I/O chassis by themselves as adapters on A-B Universal Remote I/O networks.

For a three-rack system, you should simply replace the RIO wiring, especially considering its probable age.

Unless it runs through a Class 1, Div 1, Federally-Protected Desert Newt Preserve and is cemented into conduit buried beneath the Tonopah Test Range, the cost of pulling a sturdy Ethernet or ControlNet cable should not be prohibitive.

Thanks guys! That clears things up.

For what it's worth, I'm in the middle of a PLC5 to CLX migration. Due to downtime limitations, we've had to convert in stages. I added the converted PLC5 program to an existing 1756 processor and placed a 1756-DHRIO card in that rack. Now, we are converting the 1771 racks one by one to 1756 racks with 1756-EN2T cards for Ethernet comms. Not ideal, but it does the job.

The hardware the connects with blue hose will continue to get more expensive, so the upgrade is of value, imho.

RonJohn said:

For what it's worth, I'm in the middle of a PLC5 to CLX migration. Due to downtime limitations, we've had to convert in stages. I added the converted PLC5 program to an existing 1756 processor and placed a 1756-DHRIO card in that rack. Now, we are converting the 1771 racks one by one to 1756 racks with 1756-EN2T cards for Ethernet comms. Not ideal, but it does the job.

The hardware the connects with blue hose will continue to get more expensive, so the upgrade is of value, imho.

Click to expand...

Out of curiosity, are you using the IO conversion kit to go from 1771 to the 1756 racks? If so, how do you like it? A few years back I thought of doing this, but the control panel could not accommodate the height increase. I found that I could configure PointIO to fit in the same footprint as the 1771 rack. It cost much less than the conversion kit and still minimized the electrical work required.

I've done a few 1771 to 1756 conversions. We priced the kit once and it was expensive. IMO it leaves you with a panel that is kind of still a mess. The marketing video that shows the time lapse comparison to the kit has the tech re-terminating the PLC loom wire by wire, which is the hard way.

I pigtail and wire number the 1756 IO CTB in advance with wire long enough to reach the panel field terminal strips. On swap day lift the wires at the terminals. Remove the entire swing arm from the 1771 chassis with wire attached and pull it and all the wires to the terminal out of the duct. Swap chassis, plug in the pigtailed CTBs, and then lay wire bundles back into duct and land the wires at the terminals. (Hint: use a lightweight electric screwdriver such as a Milwaukee 2101, it really speeds termination). If you are well prepared, it goes really fast.

The last one I did just a couple of months ago was a 1771 twelve slot chassis with 11 IO cards. I stared at about 9:30 and had it done before lunch.

Of course systems that do not have field terminals in the PLC cabinet will take longer.

I'm not a big fan of the conversion kits, but in certain cases the time savings makes the difference between upgrading and not. One of our customers (a 24/7/365 operation) has a large number of PLC5s each with several remote I/O racks. They only have short outages from time to time, most on the order of 10-12 hours. We have been using the conversion kits there. With proper pre-assembly and staging, two people can change out a dozen 16 slot 1771 racks before lunch using the kits. There is almost zero chance of a wiring error.

There are several things not covered in the sales literature.
1. The catalog numbers for the conversion parts are confusing and easy to mix up.
2. Every darn little piece comes in a box or plastic bag. It takes quite a bit of time just to unpack and assemble everything (something we do ahead of time).
3. The swing arm adapters are sometimes frustrating to get snapped properly into the conversion chassis.
3. The resulting assembly is wider and deeper than the 1771 chassis. If there is wire duct near the sides of the chassis, the CLX chassis will hang over the duct. If the cabinet door is close to the front of the 1771, it might not shut with the new assembly in place.
4. If you damage a part during installation it's unlikely that the local AB distributor will have a replacement on the shelf.

OkiePC said:

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Only because the hardware that uses it is going bye-bye. I like RIO and DH+; it is simple and robust, but it is going to be hard to get replacement modules in the future.

What sort of cable lengths are you dealing with?

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Well, that's the magic question, now isn't it?
WHEN will AB 'Sliver' 1771 I/O?
The chassis are already discontinued, and most of the processors.
The ThirdMarket is awash with old modules, but, at some point the pricing will essentially cause end users to move away.
Just like they did on the brick-SLC's many years ago.

danny.michael said:

There is almost zero chance of a wiring error.

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We had a vendor in to do a PLC5 -> CLX conversion about two years ago. They used the migration kit. Two of the 1492 cables that came with the kit had wiring errors. After many calls to AB, they were able to secure a wiring pinout for the cables and had to swap some pins. Needless to say they were behind schedule!

Paully's5.0 said:

Out of curiosity, are you using the IO conversion kit to go from 1771 to the 1756 racks? If so, how do you like it? A few years back I thought of doing this, but the control panel could not accommodate the height increase. I found that I could configure PointIO to fit in the same footprint as the 1771 rack. It cost much less than the conversion kit and still minimized the electrical work required.

Click to expand...

We did not use the conversion kit. Ran across one as an integrator a few years back that someone else installed in a different plant. I recall that I didn't like the lack of accessibility to all termination points,plus I thought it looked a bit goofy.

We're using straight up 1756 racks, changing out one at a time. Good idea on the point I/O; I'll need to consider that in the future. Was it time consuming converting the I/O tags over to Point?

danny.michael: thanks for the sales literature "addendum"