1794-ASB DIP Switch Settings...

I added two 1794-ASB modules to an old PLC5/40 a few weeks back. Both nodes have the same set of I/O modules on them. One 1794-IB16, and one 1794-OB8. These modules are daisy-chained on the end of an existing RIO network.

They are addressed as rack 14 as you can see in my attached screenshot (the faults you see are other stuff that's unplugged). Up until now, I was not using the outputs on the first module. Now that I want to use them, I realize they don't work. The outputs on the second module work fine, as well as the inputs on both modules. I have a feeling I just don't have the DIP switch setting correct. These are the dip switch settings:

Module 1:

   SW1  SW2

   ---  ---

8  ON   OFF

7  ON   ON

6  ON   ON

5  ON   ON

4  OFF  ON

3  OFF  ON

2  ON   ON

1  ON   ON

Module 2:

   SW1  SW2

   ---  ---

8  OFF  OFF

7  ON   ON

6  ON   ON

5  ON   ON

4  OFF  ON

3  OFF  ON

2  ON   ON

1  ON   ON

The only difference being SW1-8

This is where they show up in the PLC:

Module 1 Inputs: I:140/0 thru I:140/17
Module 1 Outputs: ???? (Not working)

Module 2 Inputs: I:142/0 thru I:142/17
Module 2 Outputs: O:142/0 thru O:142/7

I would expect Module 1 outputs to be O:140/0 thru O:140/7, but toggling those bits has no effect. I also tried all the 'unused' bits between 140 and 142, but nothing makes those outputs turn on.

I tried swapping the OB8 and mounting base, but the same problem remains, so it doesn't appear to be a hardware issue.

Any ideas????



-Eric

Eric did you auto config it?
I don't have the manual infront of me.

JeffKiper said:

Eric did you auto config it?

Click to expand...

I didn't configure the PLC5 end. Their programmed added them for me. The PLC end looks right to me though. I don't want to mess with their setup because this PLC is running a giant production line. I have my own dedicated subroutine I'm using to control our stuff. Keeps me from screwing up the line...

If I need to change something on the PLC communication end, I'll wait until tomorrow and have their guy change it. I thought maybe I had a DIP switch set improperly and could solve it myself. Yes, I'm on site on a Sunday...

Thanks for the reply!... :site:



-Eric

Do you Have the manual with you if not I will get on my computer and see if I can help.

If you Google '1794-ASB manual', the PDF is like the first or second hit.



-Eric

I wanted to make sure you had it.

Eric, the ASB manual is the 2nd Google hit.
Page 2-8 shows that switches S1-7 and S1-8 set the module starting I/ Group location. S1-7 ON and S1-8 OFF (as your working Module 2) is module group 2 location. Both ON means the module Starting I/O Group 0 location.

Starting I/O Group​

The starting I/O group is the first group of input and output circuits
that correspond to one word in both the input and output image
tables. These starting I/O groups are numbered 0, 2, 4 and 6. In​

FLEX I/O, one I/O group corresponds to one I/O module.

Click to expand...

Also, it has been a long time ago, but A/B has changed the functions of some of those dipswitches, so make sure of the hardware series vs. the manual. IIRC, I got bit between versions B and C or D...

The most common problem I see with flex I/O is a bent pin or otherwise faulty connector between the terminal bases and/or the modules themselves.

JeffKiper said:

I wanted to make sure you had it.

Click to expand...

Yeah, I misread your post...

--------------------------------------------------------------------------

I thought I had it correct, Paul. The first module is set to group 0, and the second module is set to group 2. That should match the current settings for Channel 2B in the PLC5. Group 0 is 140, and group 2 is 142. As I said, the inputs work as expected (both groups). What I find strange is that the outputs for group 0 don't work, while the outputs for group 2 do. I would expect either BOTH not work, or group 2 to have the issue..



-Eric

No luck getting this working today. They had to run production, so I couldn't investigate. You bring up a good point about the bent pins, Paul. While troubleshooting this yesterday, I had swapped the output module and TB3 base, but the connector on that base is female, so the male pins on the first TB3 base may very well be bent.

I'll get another crack at it this weekend when they're shut down.

Thanks guys!



-Eric

OkiePC said:

The most common problem I see with flex I/O is a bent pin or otherwise faulty connector between the terminal bases and/or the modules themselves.

Click to expand...

Hey Paul, guess what it was? A bent pin!...

It was at the interconnect between the two bases (the slide-in connector). I had replaced the right side base, but the male pins on the left side base were the culprit.

Thanks to all!... :site:



-Eric