Panelview w/ Devicenet

Hi Everyone,

I've got a job in progress that requires me to use a Panelview 550 with Devicenet interface. For some odd reason, our costumer demanded a Panelview with devicenet interface, that's all that will be on this particular network, just a panelview.

On to the point of this post, when I configured the 1747-SDN, I selected COS (change of state), and 62 bytes of I/O. Now here's the weird thing, the data coming from the panelview, is shifted one word in my data table. If I press a button with a tag address of I:1.1/0, I see I:1.2/0 go high. I called A/B, and after being put on hold for awhile, the tech support guy told me that was just the way "they" did it.

I'm hoping the someone else here has been through a similar set-up, and could tell me if this guy was just blowing smoke up my ***.

Happy New Year

Jeff

Have you made sure that you have the i/o mapped right, in RSNetworx?

Yeah, I think I do. When I orginally put the Panelview into the scanners scan list, I chose 64 bytes and COS. Because of the first word in the SLC data table being reserved for overhead, I could only map to the M0/M1 files. I didn't want or need that type of set-up.

After chosing 62 bytes in the I/0 transfer, I was able to map directly
to the "discreet" area of the 1747-SDN card. But, in the advanced area of the map set-up, It shows 62 bytes, with an offset of 1. I have not been able to get rid of that offset.

Thanks for replying.

Jeff

Jeff-
I have not gone through the exact setup you have so this is partially a guess.

I set up a quick DeviceNet network file with a 1747-SDN and a PanelView. When I went to the I/O mapping I noticed that first word transfered from the DeviceNet scanner to the PLC (I:X.0 / O:X.0, X being the scanner slot number) is listed as read-only in both the input and output mapping. I can only assume these are control and status words from the plc to the DeviceNet scanner.
If you select the Advanced button under the Input or Output tabs in the scanner setup you should see that the byte offset from the Map From COS message is 0 but the word offset for the Map To is 1. This means I:0 in the Panelview will end up at I:X.1 in the plc. I:1 in the PanelView will end up at I:X.2 in the plc.

One thing you can do (assuming you can live without I:0 and O:0 in the Panelview) is to start your mapping with a 2-byte offset. In the Advancerd section under the Input and Output tab in the DeviceNet Scanner config, set the byte value in the Map From field to 2. This will then correctly map I:1 from the PanelView into I:1.1. Again, you give up word 0 in both directions. But this does give you correct alignment.

I hope this helps.
Keith

Thanks, Keith. I will definately give it a try first thing tomorrow morning.

Best Regards,

Jeff

Keith put his finger on it; the first word in the discrete Input and Output tables for the 1747-SDN is reserved for Command and Status purposes of the module itself (you have to set O:1.0/0 to put the module in RUN mode, for example).

When you map a PanelView terminal as the first thing in the 1747-SDN discrete I/O data table, you get this apparent "one-word-offset", which is unsettling when you're used to PanelView addresses that precisely match data table addresses in the SLC (like when you use DH485).

Remember that the PanelView isn't using SLC addresses; it's just referring to the offset word and byte inside the data block it's receiving across the DeviceNet I/O connection. It doesn't care where the data is coming from inside the DeviceNet scanner; in fact, it doesn't know or care that the DeviceNet scanner is an SLC.

An alternative to changing your mapping might be to use Integer or Binary files inside the SLC-500 application program to resolve this confusion; you can start your data tables with Word 0 in the Integer file to match the Word 0 in the PanelView I/O connection, then COPy them to and from the I/O tables starting with Word 1.

I usually recommend using Cyclic or Background Polled data messaging with the PanelView, despite the fact that it is the only device on the network. It will probably result in more predictable data update times than if the 1747-SDN has to send all 62 bytes every time one bit changes in an variable display.

DeviceNet is a great network for PanelViews when you are communicating directly to drives or motion controllers, or if you have a very small application that fits into a tiny data table, but it sure can be confusing when you're used to the simple addressing methods used on the other networks.

Um,

I wonder why the A/B guy in Cleveland wouldn't share all this with me.

You would have gotten the same answer from me a day previous.... this year's hangover was wicked.

Keith & Ken have it.

Sounds like the A-B guy didn't know and he just passed on the "Black box" explination to you.

With A-B Messages, block transfers etc..... you will find that the "1st" word isn't always word #1.

Roger