SLC 5/04 to DHRIO to NET-ENI to SLC 5/03

OK, All... out of the hundreds of different comm scenarios I've found here I cannot seem to get this one licked.

I have a SLC 5/04 that controls a few last nodes on DH-485, which we're trying very hard to migrate away from....

Next node up for migration is a SLC 5/03. We hooked this up to a NET-ENI and can see it in RSLINX and connect to via Ethernet. Physical connection works!

Since I have a Controllogix DHRIO on the same DH+ network with the SLC 5/04 I need to talk to... I thought this would be a snap but so far no love.

I set up a routing table in the DHRIO as described in technote 32116 (which covers messaging through a SLC 5/04 to DHRIO to SLC 5/05). Not my exact scenario but I thought it would help.

Anyhow, when trying to do a test read MSG from the 5/04 through DH+ to the remote DHRIO I get a "Target Node not responding" error.

Does anyone have any pointers or 'gotcha's' with this setup. Do I need to do something on the NET-ENI side as well?

Any help would be greatly appreciated!!

Thanks, John

If you are writing a message from an SLC processor to the CLX

you may need to map the file to the CLX under the Logic tab in the

5000 software if you are sending n14:0 length of 10 map 14 to a tag

array you create and call it anything you want with a length the same

as the file you are sending this should map the data to the tag

I don't think the CLX will recognize anything with a :

Hope this helps

I had to read the explanation a few times to figure out what's going on.

Aside: Joel, there are no ControlLogix controllers involved, just the 1756-DHRIO and 1756-ENBT modules. They can handle this sort of network bridging themselves.

Check to be sure that the serial port of the SLC-5/03 is set up for the same Link ID number as you have defined for the 1761-NET-ENI in the routing table you configured in the 1756-DHRIO.

The Net-ENI might correctly handle the Link ID, or it might not. I would need to spend some time with a protocol analyzer to figure it out.

Ken, I'm sorry for the long winded situation report. It's a little twisted, to be sure.

Anyhow, your comment on the DF1 link iD in the 5/03 is promising. I'm pretty certain it doesn't match the routing table in the DHRIO. I will check and report back in the AM.

If anyone else has suggestions...I will take them!

Thanks Ken.

John

Ken Roach said:

...The Net-ENI might correctly handle the Link ID, or it might not...

Click to expand...

Ken,

I don't think it will?

The SLC 5/03, using DF1 behind the NET-ENI, is not even transparent to the 1756-ENBT, let alone the 1756-DHRIO. Any Link ID set in the SLC 5/03 will not be accessible to the DHRIO via the ENBT.

This is what I think will happen...

When the SLC 5/04 sends message data to the DHRIO, its Routing Table sends it to the 1756-ENBT, which in turn sends it to the NET-ENI IP address, not a Link ID address. The NET-ENI then passes the message data to the SLC 5/03 using DF1. The SLC 5/03 then sends a done reply via DF1 to the NET-ENI. The NET-ENI IP address then passes the reply to the ENBT IP address, no Link ID. So it cannot go from the ENBT to the DHRIO. This is because their is no Routing Table for the ENBT to handle Link IDs. It's one way traffic only.

John,

I'd be chuffed if you can get it working, but somehow I don't think it will?

Regards,
George

The link ID on the SLC 5/03's DF1 connection matched the routing table in the DHRIO, so no joy there.

My fall-back is to message in-and-out of the ControlLogix. Seems a little clunky. I sure wish we could get the bridge working by itself.

Any other suggestions or comments will be greatly appreciated.

Thanks,

John

jkelleyus said:

...I sure wish we could get the bridge working by itself...Any other suggestions or comments will be greatly appreciated...

Click to expand...

Just so your clear on the issue and how you've phrased it...

The bridge (ControlLogix Gateway) itself is not your problem here, the NET-ENI is. It will not forward the destination Link ID to the ENBT. Without the destination Link ID, and because the ENBT has no Routing Table of its own, the ENBT cannot automatically route the MSG reply to the DHRIO network. The data stops at the ENBT.

The NET-ENI is a basic DF1/Ethernet interface. It is not really designed to, or intended to, handle two way multi network Link ID routing.

So, you cannot initiate a remote MSG from the...

...SLC 5/04 >>>1756-DHRIO >>>1756-ENBT >>> 1761-NET-ENI >>> SLC 5/03...

...because the reply will only go back as far as the ENBT.

But, you should be able to initiate a remote message from the...

...SLC 5/03 >>> 1761-NET-ENI >>> 1756-ENBT >>> 1756-DHRIO >>> SLC 5/04...

Why this way and not the other way?

In the first setup that does not work, the remote MSG initiated from the SLC 5/04 goes through the DHRIO, which uses its Routing Table to reach the Ethernet network and then the destination Ethernet device. The reply from the Ethernet device must have the DH+ destination Link ID so the ENBT can automatically route the reply back to the DH+ network and then to the destination DH+ device. It does not receive a destination Link ID from the NET-ENI, so it cannot reach its destination.

In the other direction, the remote MSG initiated from the SLC 5/03 goes through the NET-ENI, then to the ENBT. Because the ENBT is initiating a command, the DHRIO Routing Table is accessed to decide where the destination for the command is to be routed. Once it reaches the destination DH+ device, the device then sends its reply back to the DHRIO, which uses its Routing Table to access the Ethernet network, and then the destination Ethernet device. The reply is delivered successfully.

Looking at your bigger picture...

Rather than use the somewhat limited 1761-NET-ENIs, I would be more inclined to migrate the older DH-485 SLC nodes to Ethernet by either...

a) Swapping them out for SLC 5/05 processors (edited program)

b) Swapping the processors out for 1747-AENTR (Ethernet comms module), making the SLC chassis a remote I/O rack. Then use a newer CompactLogix to own that rack (new program)

c) Swap out the whole SLC chassis for a newer CompactLogix and necessary I/O modules (new program)

Just some options that you might not have thought of or have been aware of.

If you were just connecting a couple of these SLCs together using Ethernet, then NET-ENIs may be fine, but they can run out of connections pretty fast if you are passing a lot of data between controllers and HMIs. The fact that this setup is being complicated by having used a NET-ENI is further highlighting their shortcomings.

The NET-ENI is an option I see users going for when they do not have either the budget, the knowledge, or the inclination to migrate to Ethernet proper.

Regards,
George

Thank you for the very detailed reply, Geo! Much appreciated.

Our plant is in a high state of 'flux' right now, due to a lot of upgrading going on and a lot of equipment that hadn't received updates for years under prior ownership.

Hence, this makes our modernization program a huge undertaking WHILE THE PLANT is in operation. Someone mentioned it's quite like "building an airplane in-flight". I agree...

There are four nodes left in our DH-485 network. All of them need a comm path to the SLC 5/04 until it can be modernized. Doing a 1747-AENTR is likely our next... next step. But first I need to get everything off the DH-485 AND DH+ links that are both utilized on the 5/04. That's the reason I haven't considered a 5/05.... a full local rack and the need for DH+ (for a little while yet).

The -485 nodes are not challenging uses. Some remote MCC start/stops and overload monitoring, limited discrete signals to remote processes, etc. If the MSG initiation from the far side will work, it might make a good interim solution?

Again, thanks for the detailed reply. Any and all assistance \ advice is greatly appreciated!!

John