ControlNet For Control Logix Tag addressing

To make a long story short I am in the process of upgrading a PLC5/40C to a 1756-L81ES. I will be installing a 1756-CNB module. This processor talks to 3 different PLC’s. They are the following
Node 1 PLC5/40C
Node 20 PLC5/40C
Node 48 1756-CNB to 1756-L81 PLC slot 0.
Node 30 1756-L81ES (Upgrading from PLC5/40C)

I am going to be using rsnetworx to reschedule the network. In the I/O tree in studio I have node 1,20 setup for controller PLC5. I tell it what node it is exc. For node 48 I set it up as a CNB module and inserted the control Logix controller as slot 0. My question is if I want to send data let’s say N74:0 from Node 30 to N73:0 in node 1 for a length of 8 Bits where can I configure that? In rsnetworx I can send and receive data from on plc5 to another easily under the scan list configuration tool but if I select Node 30 in slot 0 and right click there is no option. I had to delete the old plc5 that I’m upgrading from the ControlNet configuration to merge my new processor into the schedule. I know this deleted all my connections from the old plc5 but I have a backup copy to look at. The question is how can I tell the new controller to take data from a tag and send it to INT files on the other plc5 through the ControlNet schedule. When I click node 1 in the I/o tree it just says what node it is exc and doesn’t give the option to correlate a tag that I want to send to another PLC and receive data exc.

In RSNetWorX you have to open the scan list for each PLC-5 if memory serves me correctly. You have to go to the source and insert a Produced connection and then go into the destination and insert a Consume connection. It has been a while so the process isn't one I have done for ages.

I'll see if I can fire up that software and jog my brain.

OG

Yes, you open your source PLC Scanlist Configuration, then in the blank space right-click and select Insert Target. Select Send, then the size (words) and the Output Address (Produce Tag). Note the Produce BufferID.

Then go to the other PLC-5 and do the same. Select Receive Data From and select the correct BufferID. Then set the size and the Input Address (Consume Tag). Save it all.

Recommend keeping all send data in one data file and receive in one separate data file. It can get confusing if the data is all over the place.

Each controller needs a Status Address (Data File) that shouldn't be used for anything else.

OG.

While the intended approach (replacing the CNet PLC5 with a 1756-CNB carrying the same Node Number) might be viable, I'd strongly suggest making the Logix CNet bridge the new Keeper (Node Number 1) of the network.

Yes it will require re-addresing the current PLC5 Keeper to something else than '1' and 're-mapping' the data transfer, however, the Logix5000 RSNCN interface is far superior to the thirty years old PLC5 one.

Also, please take some time and thoroughly study the ControlNet relevant, available manuals; they are somehow unique when compared to other mainstream communication protocols' ones.

Thank for the information I will keep all this in mind. I have figured most of it out and how the data transfers exc. One thing a am concerned about is when you enter scanlist configuration and under parameters the is a bufferID you guys are talking about. In my scanlist I have 1,3,5,7,9. I assume these are attached to different processors in the network. Can these be changed or accessed in rsnetworx so I can see what bufferID goes to what processor? I will keep in mind about making the CNB the active keeper of its not to complicated. Again thank you all for the help!

1, 3, 5, 7 and 9 are the Node Numbers (addresses) of the devices which are part of the CNet Scanlist. Said Scanlist is part of and being enforced by the lowest network Node Number which, in your particular topology is the PLC5 carrying Node Number 1; the lowest Node Number device is called 'The Keeper' since it has the above stated functionality.

The data transfer schema is colloquially called Scanlist; users access and configure the Scanlist deploying RSNCN onto the Keeper node.

Okay cool! If I went to insert a new connection how exactly do I change the bufferID under TAG. I can double click but it only allows me to type a tag in. Is there a way to select a bufferID and associate a tag with that node?

OK, a few things.....Maybe you've got this already but for anyone reading this later....

Send data from the PLC-5 to the CLX using Produce/Consume
If you want to send data from the PLC-5 to the CLX then you use RSNetWorx to configure the PLC-5 to produce a tag. The BufferID value can be changed by double-clicking on it. But it isn't necessary. You have a fixed number of buffers available and that number is different for the 5/20 than it is for the 5/40. Just be mindful that these buffers are independent of the node numbers. If you set up a scheme that helps you track what these buffers do, great. But by default, they are not tied to the node number.

On the CLX side, everything is done in RSLogix/Studio 5000 through the I/O tree. You must know the BufferID being used by the PLC-5 and enter that in the Remote Data field when creating your Consume tag.

Send data from the CLX to the PLC-5 using Produce/Consume
In the Logix software you configure your CLX to produce the tag. The destination is not important to the CLX and BufferIDs are not something we deal with.

For the PLC-5, you use RSNetWorx and open the ScanList Configuration. Right-click on the CLX controller (not the CNB) and inset the connection. In the Value column, enter the name of the produced tag in the CLX. You don't use a BufferID when the Producer is a Logix controller.

That should help I hope. Oh, and I'm not sure you can produce less than an Integer tag. So to produce the 8 bits, you'll need to produce an entire integer.

OG

Thanks for the information it helps out. I will try what you have given me and if I have anymore questions I will get back to you. I have set everything up in the I/O tree now onto RSNETWORX.

Where do I find the BufferID for each of the processors? In the RSlogix5 Program or RSNETWORX? I found some info but I'm still a little confused. I found the EDS File but it doesn't give a lot of straight forward info. Here is what it says for Parameters.

Param3 = 0,,,0x0000,0xC6,1,"Consume Buffer ID","","",1,96,1,,,,,,,,,;

In the Communication Parameters list box, view and/or select the buffer location

Displays the following:

the name of the connection buffer (which is commonly obtained from the EDS file)
the consume buffer ID, which represents an integer value that uniquely identifies a specific consumer connection.
To complete a connection, the Consume Buffer ID must match the Produce Buffer ID established when you insert a target for a connection.

Tip:
The network allows devices to communicate via ID numbers (for example, the Consume Buffer ID). These numbers are device addressing and naming independent values that can be used to establish a connection. Devices that support ID messaging are typically scanners, but can also include devices such as PanelView terminals. The scheduled connections between consumers and producers of data are called peer-to-peer connections. For more information, see the Producer-Consumer model.


Tip:
The number of available buffers is dependent upon the target device.





On the CLX side, everything is done in RSLogix/Studio 5000 through the I/O tree. You must know the BufferID being used by the PLC-5 and enter that in the Remote Data field when creating your Consume tag.

I think I understand now what's going on with Produce/Consume buffer ID's. If I insert a new connection on node 1 with a produce buffer ID of "5" under parameters and under Output N74:0 of 8 words then any other Node with a Consume buffer ID of "5" will consume that data to the Input address of your choice lets say N73:0 for 8 words. I think this is how it works at least.

Yes, you've got it! And you may have noticed, when you select consume buffer 5 it fills in the number of words with the correct "8" that is being produced.

OG

I'd recommend just upgrading to Ethernet, personally I think controlnet is garbage.

So rip out all of their existing hardware? Sure, if you wanna bust the budget by replacing all of their PLC-5 in the process. I want whatever budget you have control over!

ControlNet is actually very solid. The downside is the scheduling requirement. I certainly wouldn't use it on a new installation. But, for an existing system it works just fine.

OG

Nope, I've been over several projects that I rip out DH+/DevNet/ControlNet. If something is blipping your controlnet network how are you diagnosing it? You can mess controlnet up just by having a missing node.

I feel controlnet is great, when it works but its a dumpster fire when it has a simple issue that should be easy to diagnose.