SLC Remote I/O Comms With 1794-ASB

Looking for some help on two different matters with a new SLC remote I/O network I just setup using two 1794-ASB modules and a 1747-SN/B module. I search the forum and found lots of information but after two weeks I'm still no further ahead. I do have all manuals and referred to them.

Some background on my setup; I have the 1747-SN module in slot 12, the last slot of my processor rack. I have two remote I/O stations on this where I have the dip switches set to communicate at 115.2 kbs. My first remote I/O rack is a 1794-ASB/E and my second remote rack, the last rack, is a 1794-ASB/D. I have a 150ohm resistor on both ends of the network.

I set my G file up to look at rack 0,1/2,group 0 for the 1st ASB and the second at rack 0,1/2, group 4 and I set the ASB dip switches to match this setup.

My 1st problem is that I can get communication with the 2nd remote I/O station ASB/D but I can't achieve communication
with the first remote I/O station ASB/E. It seems to be a problem with the series E module as I swapped locations and set the dip switches and the series D worked in the 1st remote I/O location and the Series E would not work as the last rack. Does anybody know of any issues with the the Series E module in the setup I have or have any suggestions.

My 2nd problem is for the rack that is communicating, the last rack assigned as rack 0, starting group 4. I have an OA16 in the first base next to the ASB module and I have an IR8 in the next base so when setting up my BTR/BTW for the IR8 analog module in the 2nd base how should my BTR and BTW be configured. I currently have the BTR as rack=0, slot=4, group=0, MI:12.300, length 13 and the BTW as rack=0, slot=4, group=0, MO:12.400, length 3. But this is not working!

I appreciate your help!

Ken Roach, I see you have a lot of replies with similiar concerns, do you have any suggestions for me?

It turned out that i have a bad ASB/E module as i tried another and it worked fine!

Still trying to setup the BTR/BTW's with my IR8 modules if anybody has any input! See attached .jpg for current configuration!

I think I have a lot of posts on this because I'm patient. Since RIO, especially with SLC's and FLEX, requires a good deal of detailed information to make it work and most folks who go to a forum like this for their technical support aren't up to the task of posting thorough and clear information.

Present company excluded, of course !

RIO addressing uses the Rack / Group / Slot (R/G/S) nomenclature. The easiest way to use FLEX is to use Standard addressing mode, which makes each FLEX module a Group.

First Adapter
RGS 000
RGS 010
RGS 020
RGS 030

Second Adapter
RGS 040 OA16
RGS 050 IR8
RGS 060
RGS 070


From your screenshot, you've already seen that the second slot of the second adapter is Rack 0 Group 5. Because S1-1 must be ON, the analog modules are "Slot 0".

FLEX doesn't use the "Last Chassis" function, so that's not causing your problem.

Hmm.

Your screenshot shows you're using the conditions of the Block Transfer /ER and /DN bits both being false to trigger the Block Transfer instruction, which is classic continuous logic.

I'm not sure if the 1794-IR8 module will handle both BTR and BTW continuously.

At the least, you should alternate the BTR and BTW instructions. Use an XIO instruction for the /EN bit (.15) from the OPPOSITE instruction in each instruction's preconditions.

Good examples of BT logic can be found in RA Knowledgebase ID# 18461.

I don't have a 1794-IR8 manual handy to see if it has a "powered up but not configured" bit in the BTR data. And for the first time I've ever seen it, the RA PDF server is down.

Check also the Firmware revision for the 1794-ASB/E. There was a PSA a few years ago for a particular firmware version that could corrupt BTR data in some cases. It wouldn't cause your BT's to not work, but you should at least check for it just in case.

Thanks for your help Ken! I was able to configure the BTR/BTW with the information you supplied on the RIO addressing and also it seemed to be critical that you call for the proper length, for the IR8 it was 3 for the BTW and 11 for the BTR.