Channel Failure warnings

[Scot]

Is there a common wiring method to prevent the "Channel Failure" warning in Do-More for analog inputs that are not in use? I don't want to disable inputs with jumpers because that would require a shutdown if another input is needed later.

[willpoll]

Not sure what hardware you're referring to specifically, but if you're using a F2-8AD4DA1 on H2-DM1, you can set unused channels to 'disabled' in software under 'module configuration'.

-Will

[Scot]

These are F2-08AD-1 cards. I have quite a lot of them in service but with Designer 2.5.2 I get a warning panel every time I connect to one of the PLCs now about the issues reported in the I/O system.
I can see where that could be useful. It would show if a channel really had a problem. But only if all channels are fully populated and the warning wasn't ignored because it appears every time. It's like the warning that cried wolf.

The only thing the manuals for F2-08AD-1 cards say about unused channels is to change jumper settings, which is foolish unless the PLC is on a simple little device that can be shut off whenever you want. You can't just shut off a PLC that's operating a plant to change jumpers.

I doubt I'm the only one with this problem, so I thought there might be a standardized solution. It doesn't appear that way, so I'll have to just connect some 5k resistors between 24v+ and the card inputs giving me just over 4ma on the unused inputs.

[BobO]

We fixed a bug or two that were preventing the warnings already being generated by some modules from propagating, so there are definitely ones showing up that were always there before.

A bit of a no-win for us on this though; some were concerned that the warnings weren't showing up, others annoyed that they are now. In the end, reporting them is the most correct answer, but we will definitely look at ways to disable/suppress for new development.

[Bolt]

I'm also in the category of being annoyed by the warnings that started showing up in about 2.2 or 2.3.  I understand the logic of it's a warning, it's active so should be displayed.  But I look at more like the Xnn bit will be set if there's an analog input failure, and it will qualify for that, so that's enough for me.

You can't just shut off a PLC that's operating a plant to change jumpers.

For me, with a BRX, disabling them in the software is the same problem, you can't just shut off the PLC to change the module configuration settings.  I also don't think I can disable channels selectively, say disable 1 and 5, not just enable the first 6 out of the 8 channels?  Maybe I'm wrong?

[BobO]

For me, with a BRX, disabling them in the software is the same problem, you can't just shut off the PLC to change the module configuration settings.  I also don't think I can disable channels selectively, say disable 1 and 5, not just enable the first 6 out of the 8 channels?  Maybe I'm wrong?

For internal channels, setting them to anything but 4-20ma should eliminate warnings from disconnected channels. For -1 expansion modules I would think setting them to 0-20ma, instead of the default 4-20ma would do it. Not sure where -2B expansion modules park when undriven, but worst case you could set them to a wide bipolar range and I think that would work.

[BobO]

I'm also in the category of being annoyed by the warnings that started showing up in about 2.2 or 2.3.  I understand the logic of it's a warning, it's active so should be displayed.  But I look at more like the Xnn bit will be set if there's an analog input failure, and it will qualify for that, so that's enough for me.

It wouldn't have been an issue if it was working as originally intended from the start, since you would have resolved it during initial development. After deployment, the warnings would give you potentially critical information, which you would then be happy about. We knew it would be an issue for some, but felt that fixing it was the right thing to do.