Eric Nelson
Lifetime Supporting Member + Moderator
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:
Module 2:
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
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