MSG through DH+ and ControlNet

fpap · Jun 24, 2011

Hello, I am trying to send a message (PLC-5 typed read) from a PLC-5 to a ControlLogix Controller. I did it successfully the first time, when I was just testing and the topology was the PLC-5 controller connected to a DHRIO module that was on the same chassis where the ControlLogix controller was connected. But now I have the real topology: PLC-5 on chassis, lets say, A; DHRIO module and ControlNet module on chassis B; ControlLogix controller and ControlNet module on chassis C. PLC-5 is connected to the DHRIO module on chassis B, and ControlNet module on chassis B is connected to the ControlNet module on chassis C. Under this configuration, I just cannot read the data.

Any suggestion? Is this topology valid?

Thank you very much!

Fernando

Ken Roach · Jun 24, 2011

It's a valid topology, but you're going to need to configure a Remote Link in the 1756-DHRIO module.

You can start reading about this technique in the obsolete user manual for the old 1756-GTWY software (all of this is included in RSLinx Classic Lite now):

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1756-um513_-en-p.pdf

Or look around the RA Knowledgebase.

I will try to post more on this later.

fpap · Jun 24, 2011

Thank you very much Ken! I was wondering if I should need to configure the DHRIO module, and now you confirmed that. I am trying to set the routing, but with no success yet...

fpap · Jun 24, 2011

I am confused... Is it required to have a DH+ node on the controller chassis? I think it is, I wish not...

Please somebody confirm or discard that.

Ken Roach · Jun 24, 2011

You do not need the 1756-DHRIO in the same chassis as the ControlLogix CPU. The path through ControlNet to a second chassis is valid.

This is hard to describe because I haven't done it in a long time and you can't configure it (and get screenshots) without physical access to a 1756-DHRIO module, because the configuration utility only launches when it sees a real module.

Download the 1756-DHRIO User Manual, Publication 1756-UM514.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1756-um514_-en-p.pdf

There's an example starting on page 3-11 of sending a message from one PLC-5 to another across the two channels of a 1756-DHRIO.

Your application will be similar, except instead of "Link ID 2" being the DH+ network on the second channel of the DHRIO module, it's a link that goes across the ControlNet to the ControlLogix CPU.

fpap · Jun 24, 2011

I have attached two images where it can be seen the routing table I have defined and the message configuration. I really can get why it isn't working. I have tested the other way round, from reading a value from PLC-5 to controllogix (in this case local), just to be sure cables and everything else it's ok. And indeed, I could get the value, so there must be something wrong with the routing table, or message configuration, or... I don't know...

sthompson · Jun 24, 2011

Make sure you are not confusing the DH Address, and the Link ID, they are not necessarily the same. Wouldn't the Remote Link be Other? Take a Screen Shot of General and Channel Configuration from the DHRIO setup, and post them.

As Ken said, it is hard to give advice if you don't have the actual Devices to work with. I haven't worked on any ControlNet Systems. So, hopefully Ken will pop back in.

The other option is posting your Program Files for both PLCs, so we can see the exact setup. I think you need a little more setup, to get a full path to the ControlLogix Processor.

Stu....

Ken Roach · Jun 24, 2011

Almost there !

The "Remote Bridge Link ID" = 7 will get your message to the backplane of the chassis of the 1756-CNB at ControlNet Node 3 (the ControlNet attached to the module in Slot 0 of the gateway chassis).

Choose carefully, because I see that you have two 1756-CNBs in the same chassis, and they're at the same ControlNet node address, so they have to be on two separate ControlNet networks.

The "Remote Station Address" needs to be the Slot Number of the ControlLogix CPU in that chassis. In this case the "remote network" is the ControLogix chassis.

I did find a good RA TechConnect illustration of this kind of message in RA Knowledgebase Article 30049, if you have a support contract.

fpap · Jun 24, 2011

Yes! Thank you! I was setting wrong the Remote Station Address on the message configuration. When I set it to 0, everything started to work!

I really appreciate your help, you are awesome!

Thank you very much

Best regards

Fernando

fpap · Aug 5, 2011

Hello again,
Now I need to communicate two ControlLogix controllers via DH+. For instance, I need to read an array from controller B and get the data on controller A. I am not sure about which instruction should I use. I tried with MSG, with every option it has, but without success...

Any suggestion?

Thanks in advance

Best regards

Fernando

gravedigger02 · Aug 5, 2011

You would use the MSG instruction with the message type CIP data table write or read and make sure your path is correct. Look into Chapter 4 of Publication 1756-RM003K-EN-P for more details.

fpap · Aug 5, 2011

Ok, I will try it and then I tell you what happened...

Thank you!

fpap · Aug 8, 2011

Yes, it worked!

I used a message configured with:
Message Type: CIP Data Table Read
Path:1, 2, 2, 3, 1, 0

Explanation of this particular path:
Backplane, Slot, DH+ Channel A, Destination node, Destination backplane, Destination slot

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MSG through DH+ and ControlNet

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