Remote IO With PLC5

All,
I have a PLC5 80/E that has an existing Remote IO network running on it. Today we tried to add 4 powerflex 700 VFD drives to the network at racks 24 and 25 (Octal) using the 22-Comm-R modules, where each drive is a 1/2 rack. When trying to do the auto-configure on the PLC5, it would pick up the existing racks, but it does not see the new racks at 24 or 25. If I try to add them in manually, I get the error 'Configuration edits not accepted by PLC'. I looked on the AB knowledge base for this error, and the two suggestions they had did not look like they are the reason. Currently the RIO network has nodes 0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 20, and 21 on it, so 17 racks. Under the channel 1B properties in Logix 5 there are 38 devices listed under whichever rack they are associated with. All the dip switches on the 22-Comm-R modules were checked and looked correct, as well as the wiring going to each drive. These were inserted into the middle of the network, so none of them will be the last rack. Is the network telling us that it is full and that no more devices can be added, or is there something else that we could possibly be missing?

This is from memory, I haven't use a PLC5 in years. Is the I/O table in the processor big enough? What I mean is "Does the I/O addresses that you need exist in the I/O table? The I/O table may have to be expanded.

Thanks for the reply.

From what I remember when I was looking at it today, while I was online with the PLC, the I1 table only went to I:237, along with the O0 data table. So the PLC5 doesn't automatically add these new registers in when you try to add the new remote IO racks into the scan list (while in remote program mode), or if you add the rack into the I/O configuration as another chassis?

It's been awhile but I remember some things can only be done in full program mode (a drag if people don't like the PLC to be offline). I/O config may be one of those.

Yes, if the I/O tables are not big enough they will need to be expanded. You can't do this when the processor is in run mode. I don't remember if the I/O is expanded automatically even if it's in program mode.

From what I recall...

The PLC5 IO table is automatically set by the processor type (you can neither add not delete IO from the IO tables). I think a PLC5/80E would have Inputs and Outputs 0-277 or more - but that is per my memory. So adding hardware as rack 24 and 25 shouldn't be an issue.

If you have tried an autoconfig, I assume you have had it in program mode b/c I think it will only autoconfig in program mode. You can manually add things in run mode (I think). It would a t least need to be in remote Run mode (keyswitch cannot be set to run).

If you are looking at the channel configuration for the RIO channel these connect to and you are seeing 38 devices - that may be an issue. Even if a processor has IO space for more devices, there is a limit on the number of physical devices PER CHANNEL. If you have hit this limit, you would need to setup another channnel as RIO Scanner and wire to this channel.

Don't know if that is your issue, but 38 devices sounds high to me for one channel.

It's been a long time, but isn't there a limit of rack numbers / devices per channel?
Max of 16 rack numbers / 32 devices per channel comes to mind.

How is your local rack defined? Size and addressing?
Wouldn't at least rack 0 be local ?

That sounds famililar - 16 logical racks but a limit of 32 physical devices - PER CHANNEL.

The PLC can have more overall racks and devices, but they must be on other channels.

just as a test ...

if you can shut down for a while - unplug everything else - and then try to AutoConfigure the new stuff ... that will at least tell you something ...

Scooby1 said:

Thanks for the reply.

From what I remember when I was looking at it today, while I was online with the PLC, the I1 table only went to I:237, along with the O0 data table. So the PLC5 doesn't automatically add these new registers in when you try to add the new remote IO racks into the scan list (while in remote program mode), or if you add the rack into the I/O configuration as another chassis?

Click to expand...

You are adding in racks 24 & 25, thus your I/O table will have to go above 237. You will need to go to program mode to add 240-247 and 250-257. Hope this helps.

It has been a few years, but I don't recall ever having to "blow out" the data table for I/O on a PLC5. I thought they were all just there. Also, why autoconfigure? That is just a luxury for a RSLogix5 file as long as what you download is right. You know what you have, set it accordingly, download and then troubleshoot it if there are errors.

Thanks for all the replies.

Once we get the chance, we are going to isolate the 4 new drives just to make sure we can see them without anything else on network to see if we set up the 20-comm-r cards correctly and to narrow it down.

I have put the program in a test PLC5 and it shows the I/O data tables go all the way up to 277, I'm not sure why with the running one, that it only goes up to 237 registers.

I've tried both adding the new racks manually in remote program and offline with a download. When I manually try to add them in remote program mode I get the error 'Configuration edits not accepted by PLC'.
If I try to add them offline and then download, when it goes back online, the newly added racks are not in the scanlist table anymore under the channel 1B tab, like they just magically got deleted out of there.

There is only one channel that we are running this RIO network on, with the 38 items in the scanlist and 17 racks, this is kind of why I'm thinking that the RIO network can't handle anymore devices and won't even let me add them manually.

I will keep testing different things and see what happens, we can only be down for about an hour a day, and that hour varies, so it makes it tough to do testing and the such since the PLC needs to be in remote program.

I appreciate all the help!

We finally got the chance to do some more testing on the drives. We set up a network with a spare PLC5 that we had laying around. We connected just the 4 drives to the test Remote IO network and I was able to auto-configure the drives and see them in the PLC5, so it seems like everything on the 20-Comm-R is set up correctly. So, the only thing I can think of is that the existing Remote IO network is full and will not let me add any more devices to it. I am hoping to use channel A as another Remote IO network for the 4 new VFDs

We finally just ended up using Channel A of a different processor to communicate with the VFDs. The only thing that we could really think of that might have been the problem was that the Remote IO network on the other PLC was completely full and that's why it wouldn't let us add any more devices, because on the other PLC, the 4 VFDs came in and communicated just fine. Thanks everyone for the help!