Slc 500 communicating with RIO

[Asset1452]

I’ve searched the internet for answers on how to do this. But I’m in need of some help. I have a slc 500 connected to a RIO. There are two racks in the RIO cabinet. I want to add an analog card to the second rack, but I’m unsure how to add in the card and receive information from the analog card. I added the card 1749-if8ih to the 3rd place on the second rack and the ok flashes. Do you have to configure these cards?

 

[Ken Roach]

Welcome to the PLCTalk forum community !

You should have a 1747-SN Scanner module in the chassis that has the SLC-500 CPU in Slot 0.

>1749-IF8IH

That isn't a correct part number, which creates some confusion.

Follow that blue cable from the 1747-SN to the other network adapters. Are they in a chassis like the one that houses the CPU and the Scanner ?

Or are they smaller modules snapped together on a DIN rail, with a 1794-ASB "FLEX I/O" adapter ?

If the module is a1794-IF8IH, then that's a pretty sophisticated module. It has a HART modem integrated into it, making the configuration and operation a lot more complicated than ordinary analog modules.

And a quick check of the Installation Instructions confirms my recollection: I don't think this module can be used with a 1794-ASB (classic A-B Universal Remote I/O), but only with a ControlNet or EtherNet/IP adapter.

So let's go back and examine that SLC-5/0x (which model number exactly ?) and the Scanner module to see if it's a 1747-SN with the twisted-pair blue RIO cable, of a 1747-SCNR with ControlNet co-ax connectors.

 

[Asset1452]

Thank you! Excited to be here and further my knowledge.

Sorry it is was 1794-if8ih, unfortunately that is what the customer supplied instead of the 1794-if4 that was in the top rack. Knowing this I can suggest getting the 1794-if4 like we were suppose to.

The cpu is a slc5/04 with a 1747-sn with the twisted pair blue Rio cable connecting to the 1794-asb.

 

[Ken Roach]

Thank you for that clarification !

My source for the compatability of the 1794-IF8IH isolated HART analog input module with only ControlNet and EtherNet/IP adapters came from the Installation Instructions for that module (right on the first page):

https://literature.rockwellautomation.com/idc/groups/literature/documents/in/1794-in115_-en-p.pdf

There is also a Knowledgebase document, QA13153 (Access Level: Everyone) that describes the specific firmware of the CNet and EIP adapters that are compatible with that module.

>1794-IF4

There is a non-isolated 1794-IF8 module, and an isolated 1794-IF4I module. Check very carefully to see what you have, if you're going to apply it to similar circuits.

When you do get the correct module, you should be able to examine the existing Block Transfer logic for the other modules in the system and duplicate and adapt it for the new one. Examples are also available in the User Manual (updated just two years ago !) for the 1794 FLEX Isolated Analog Input modules:

https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1794-um008_-en-p.pdf

If your controller is very old and does not support the BTR and BTW instructions, then you're going to have to take a deep breath and get your hands dirty examining the old M-File data buffer methods used to make 1747-SN Series B scanners perform block transfers.

They work, but they're a trip back to the 90's.

 

[Asset1452]

Thank you for this information and resources!! And unfortunately the rest of the program uses the m files to pull data from the other 1794-if4 cards so I assume that’s what I need to learn. I’ve tried to follow it, but looks very… elaborate. Unfortunately this is an upload from the slc 5/04 so the details are gone.

 

[Ken Roach]

Get some graph paper and strap in.

Can you Zip and post the *.RSS file and some information on the 1794-ASB's and the I/O modules attached to them ? The DIP switches set up the Rack/Group information and they differ between hardware Series of 1794-ASB a little.

The secret that clarified the M0/M1 file logic for me was that there are 32 BTR or BTW "buffers" that the 1747-SN can process. I think they're 64 Words each.

Instead of being carefully packed into 64-word boundaries, they're numbered M1.100, 200, 300, 400, 500.... 3200. That's why the M0 and M1 files need to be expanded to 3300 total words when you use block transfers.

The analogy I used when I taught programming classes was that the M0/M1 files are like the pass between a greasy-spoon diner kitchen and the table servers: you load up a transaction into the desired buffer and hit that bell: ORDER UP, BUFFER 100 !

 

[JeffKiper]

Man this bring backs sime nightmares. I remember making excel sheets with all the mapping back and forth for thr M0/M1. It was brutal until I realized its just a BLOCK of data going back and forth. I even had the M0/M1 data number of the elevtricsl prints so you could look at the physical layout and see how the memeory was used to pass info. That is what helped me many many years ago. A lot of reverse engineering of working systems and the light bulb finally went on as to how.