Messaging between old and new compactlogix processors

Hi Everyone,
I have to get a couple of status bits and send a run command to a another vendors PLC. My PLC is a 1769-L33ER and the one on their machine is a 1769-L32E.

Would it be easier or more robust to use consumed and produced tags for this? Or would you recommend using a couple of messages?

I have read that the messaging structure is different between the 2 different PLC models. If my PLC is the "Master" in this arrangement and initiate all the communications, what would be my communications path??

Thanks for any help!!

bump

In my opinion it's easier and more robust to use Produced/Consumed Tags.

The difference you're probably thinking of between the 1769-L33ER and the 1769-L32E is that the newer controller considers the Ethernet port to be part of the CPU, while the older controller considers it to be daughtercard located in Slot 1 of a virtual backplane. The CPU in the older CompactLogix is considered to be in Slot 0 of the virtual backplane.

If the controllers use the same revision of RSLogix 5000, this should not be a problem.

If the 1769-L32E has much older firmware, you might have to figure out if it can still consider the 1769-L33ER to be in "Slot 0" of the virtual backplane.

Bullzi said:

Hi Everyone,
I have to get a couple of status bits and send a run command to a another vendors PLC. My PLC is a 1769-L33ER and the one on their machine is a 1769-L32E.

Would it be easier or more robust to use consumed and produced tags for this? Or would you recommend using a couple of messages?

I have read that the messaging structure is different between the 2 different PLC models. If my PLC is the "Master" in this arrangement and initiate all the communications, what would be my communications path??

Thanks for any help!!

Click to expand...

This sounds like something that you could easily accomplish with a single MSG function, but I've never encountered this specific configuration, so I was hesitant to answer. I would recommend that you also monitor communication status and have your program logic respond appropriately in the event of a loss of communication.

Ken, My PLC had V21 Firmware and the other PLC has V20. Are they close enough in version to make it all work? Just so I am understanding everything, In the case of Produced/Consumed tags, my PLC (L33) would Produce the run command tag and the other PLC (L32) would Consume it, right? Then the L32 would produce a few status tags and the L33 would consume it, correct? Just want to make sure I am thinking correctly.

Bit Bucket, I was thinking the same thing about MSG function. I was planning on setting up some kind of "heart beat" between the 2 PLC's.

I was planning on doing this via discrete I/O but the electricians only pulled fiber between the 2 units so I am now a little stuck trying to make it work via communications.

Thanks for the help!!

Part of the elegance of the Produced/Consumed Tags system is that you don't have to create your own heartbeat or timing or messaging logic.

To exchange data both ways, you would set up your controller to have a Produced Tag, and also set up the other controller to have a Produced Tag. Both controllers would then Consume the other controller's Produced Tag.

In v20 and v21, there will be an option to include the connection status in the Consumed Tag, so that you'll have a status code to tell you if the other controller is successfully online and running and producing live data.

This is all well described in the ENET-UM001 user manual, starting in Chapter 6.

Thanks Ken!! You are the man.

Bullzi - once you get started with produced/consumed tags, just bear in mind that each tag uses one of the limited number of "connections" that each system can support.

With that in mind, it is beneficial to create a UDT specifying the data you want to exchange, and to create Produced/Consumed tags of the User-Defined Type.

The UDT configuration dialog tells you the "size", in bytes, of the tags created from it, and a Produced/Consumed tag has a maximum size of 500 bytes.

daba said:

Bullzi - once you get started with produced/consumed tags, just bear in mind that each tag uses one of the limited number of "connections" that each system can support.

With that in mind, it is beneficial to create a UDT specifying the data you want to exchange, and to create Produced/Consumed tags of the User-Defined Type.

The UDT configuration dialog tells you the "size", in bytes, of the tags created from it, and a Produced/Consumed tag has a maximum size of 500 bytes.

Click to expand...

ouch...the dirty little secret.

jdbrandt said:

ouch...the dirty little secret.

Click to expand...

And if you need to make changes to the Producer/Consumer structure you will need to do a download.

For me the inability to be able to make online changes usually steers me away from Producer/Consumer and towards messaging.

Bullzi said:

Hi Everyone,
I have to get a couple of status bits and send a run command to a another vendors PLC. My PLC is a 1769-L33ER and the one on their machine is a 1769-L32E.

Would it be easier or more robust to use consumed and produced tags for this? Or would you recommend using a couple of messages?

I have read that the messaging structure is different between the 2 different PLC models. If my PLC is the "Master" in this arrangement and initiate all the communications, what would be my communications path??

Thanks for any help!!

Click to expand...

Seeing as you asked, and it's no harm to know...

To get to the Ethernet port on the older CompactLogix controllers, through the virtual backplane, a "1, 1, 2,..." is used for the beginning of the MSG path. This then displays as "LocalENB, 2,..." but for the newer CompactLogix 5370 Controllers they have abbreviated this to just a "2,...", as the virtual backplane is no longer used.

If sending a MSG to the older CompactLogix controllers, you would add "..., 1, 0" to the end of the MSG path, but with the 5370 CompactLogix controllers, you simply add their IP address to the end.

Example: A MSG from a CompactLogix L32E,
to a CompactLogix L33ER with an IP address of 10.10.20.2,
would be "1, 1, 2, 10.10.20.2" or "LocalENB, 2, 10.10.20.2" <<<L33ER does not need "1, 0" to get to CPU

and reverse...

Example: A MSG from a CompactLogix L33ER,
to a CompactLogix L32E with an IP address of 10.10.20.3,
would be "2, 10.10.20.3, 1, 0" <<<L32E needs "1,0" to get to CPU

G.

Thank you Geospark!! That really clears up the mud in my mind. I appreciate the detail!!

Just wanted to let everyone know that I ended up doing Produced/Consumed tags. It was really pretty easy to set up and it is working great. IMHO the manual makes it look way more complicated than it really is.