PLC5 remote I/O expertise!

My experience with the RB Module in a remote rack (done by others) was "don't do that!"

It worked fine for 12 years until after a plant shutdown it decided that nah, we're just not going to let those integers block transfer across from this module anymore. The RB module was reading barcodes up until that day and controlling a tire sorting line. We worked on that mess for two days while the operators manhandled the tires since the sorter no longer worked. New chassis, new blue hose, new PLC-5, different adapter module, I think we got partial success by changing the hardware revision level of the chassis. We finally got a true A/B guru on the phone who said that RB module must be in the main chassis with the PLC-5. We had to rewire two slots of digital I/O and edit the program in order to move the RB module (all three racks were in the same panel, so not too terrible) and after doing that and adjusting the BTR/BTW addressing to match, we got it to work again.

This is just my only anecdote about the RB module and it is an old memory from around 2001, so keep that in mind.

OkiePC said:

My experience with the RB Module in a remote rack (done by others) was "don't do that!"

It worked fine for 12 years until after a plant shutdown it decided that nah, we're just not going to let those integers block transfer across from this module anymore. The RB module was reading barcodes up until that day and controlling a tire sorting line. We worked on that mess for two days while the operators manhandled the tires since the sorter no longer worked. New chassis, new blue hose, new PLC-5, different adapter module, I think we got partial success by changing the hardware revision level of the chassis. We finally got a true A/B guru on the phone who said that RB module must be in the main chassis with the PLC-5. We had to rewire two slots of digital I/O and edit the program in order to move the RB module (all three racks were in the same panel, so not too terrible) and after doing that and adjusting the BTR/BTW addressing to match, we got it to work again.

This is just my only anecdote about the RB module and it is an old memory from around 2001, so keep that in mind.

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Thank you for sharing your story. In my case the RB module is in the last Remote rack on the link ( I believe it is #7)). Can I do that rack on a separate link to the same controller remote I/O port. Its gonna be two separate branches ( links). First one - all racks without RB module , Second one - just rack with RB module. Controller port set up as a scanner. Or it MUST to be one link ( branch)

celichi said:

99% of the times I have had problems with DH+ or RIO, it was wiring. The shield would barf up one stand, and it would be touching something it shouldn't be.

The other time it was a ground loop being caused by some no-no's in panel design.

Wow, I still remember the old "Blue on 2" saying for DH+.

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Hello. Thank you for responding.
I find out some information that operating voltage of RIO network is 8-12V p-p.
When I am checking voltage at some RIO network connections it shows me 0V in any combination.
But sometimes the voltage Blue-GRD, Clear-GRD fluctuates 0.6-2 VAC.
Not sure how the scanner of controller works. It definitely generates some voltage. Why it is 0 ? Is that related to resistor 150Ohm?

Ivan86 said:

Thank you for sharing your story. In my case the RB module is in the last Remote rack on the link ( I believe it is #7)). Can I do that rack on a separate link to the same controller remote I/O port. Its gonna be two separate branches ( links). First one - all racks without RB module , Second one - just rack with RB module. Controller port set up as a scanner. Or it MUST to be one link ( branch)

Click to expand...

In the 20 year old case I was dealing with, we had to move it to the same chassis with the PLC-5. I am not sure if that requirement is documented anywhere or if it is specific to a particular hardware combination. I have a vague memory of having to use a certain series chassis in the remote rack we were trying to get it to work in and that yielded partial success.

Bear in mind that it worked for a decade with no known hardware changes while mounted in the remote rack. Then the plant was shutdown and that machine powered off for a few days and when it came back up, the RB module would no longer communicate with the PLC-5 (Errors on the block transfers). After a lot of parts swapping including the remote chassis, we got the messages to complete, but the data in the most important BTR block was all zeroes.

I looked for a manual, but not finding the exact right book online. This was one of those books that we kept a paper copy. I seem to recall having a pdf version of it way back then, but it was one of those that was scanned and not searchable and that was 20 years ago. That module was discontinued in 2011.

My story is anecdotal at best and probably not 100% accurate memory!

Rockwell still has Tech Notes available on the RB module. They mention local or remote is acceptable.

But when it is in a remote chassis the update speeds are going to be slower since the data has to be sent over RIO. There are also buffer limits on the RIO network. I think your AB guru knew better from having actually used it in real applications. They knew that RIO was not a good idea and that it should instead only be used in the local chassis.

The Tech Support site has a dead link to the manual. It might be floating around somewhere still.

OG