I have two L30 CompactLogix running on version 30 Studio 5000. They are both currently online and in production so they cannot be brought offline. The problem is that I need to produce a few tags on the one PLC and then consume them on the other. I realized that you cannot create these tags while online so I'm looking for other options. Is it possible to create these tags offline and then import them into the online program? Any suggestions or prior experiences are appreciated! Thanks.
Creating Produced and Consumed Tags Online
- Thread starter mjosephs
- Start date
dmargineau
Lifetime Supporting Member
Welcome to the Forum!
Implementing a Produced/Consumed data transfer between two controllers requires the creation of the relevant Data Type tags and the addition of both 'connected' CPUs within the 'IO Tree' of the 'corresponding' one.
Unfortunately, this procedure will require Offline configuration and Download to both CPUs.
Implementing a Produced/Consumed data transfer between two controllers requires the creation of the relevant Data Type tags and the addition of both 'connected' CPUs within the 'IO Tree' of the 'corresponding' one.
Unfortunately, this procedure will require Offline configuration and Download to both CPUs.
Depending on Version of 5000 - You can create a UDT with everything you need and a SPARE DINT[xx] and REAL[xx] online. Reason for the spares is once you create it and utilize it with a tag you won't be able to change it online anymore.
Then use regular messaging. We have actually gone away from P/C tags lately and gone back to messaging. Way easier to maintain when you can't shut things down.
Then use regular messaging. We have actually gone away from P/C tags lately and gone back to messaging. Way easier to maintain when you can't shut things down.
AutoMax
Lifetime Supporting Member
Yet another poster slagging produced/consumed tags. Has the world gone crazy or have I?
dmargineau
Lifetime Supporting Member
No it/you did not; this is 'it works' amateurism at its best.
The apparently satisfactory end result of Explicitly transferring data while ignoring of the mechanism's functionality is the 'easy way out' strategy or the lack thereof any strategy.
AutoMax
Lifetime Supporting Member
OK, thanks. I was starting to worry...
dmargineau
Lifetime Supporting Member
That's where you're missing the 'professional' point...And keep going at it, for 16 years nevertheless...
Produce/Consume is not messaging...P/C is I/O...
There are numerous scenarios where MSGing is preferred...Substituting for I/O Class communications is not one of them...Or at least not in my endeavors...
Bit_Bucket_07
Member
I agree. The inability to modify P/C data exchange online renders the method unacceptable for a continuous process controller. Using a MSG function also allows additional control that you can't get from configuring producer/consumer tags. For instance, it is possible to send messages only on exception, so that you don't create unnecessary traffic on the network by redundantly sending unchanged data repetitively.
AutoMax
Lifetime Supporting Member
Am I the only one that uses p/c binaries to trigger messages?
In all seriousness, when I'm installing Rockwell PLC's I always configure spare p/c tags, and I also generally configure some spare network I/O and drives appropriate to the installation and inhibit them. I can't take processors down during production, so I plan ahead.
Do you guys install systems with no spare inputs or outputs?
In all seriousness, when I'm installing Rockwell PLC's I always configure spare p/c tags, and I also generally configure some spare network I/O and drives appropriate to the installation and inhibit them. I can't take processors down during production, so I plan ahead.
Do you guys install systems with no spare inputs or outputs?
jstolaruk
Lifetime Supporting Member
Design verification, tryout, and customer run-off is done at the OEM so at customer site, installation/commissioning is mostly worked out in advance and if not, program changes requiring processor shutdown aren't a big deal.
Definitely a case of "horses for courses".
You have both methods of data exchange available, and you choose which is most suitable for the application, and of course, it's not impossible or impractical to use both methods in one system.
dmargineau - yes, P/C is I/O, but you can add and delete 1756 I/O modules online, so why not P/C tags ?
You have both methods of data exchange available, and you choose which is most suitable for the application, and of course, it's not impossible or impractical to use both methods in one system.
dmargineau - yes, P/C is I/O, but you can add and delete 1756 I/O modules online, so why not P/C tags ?
Lord Farquaad
Member
I do the same. Nice big UDT with varied data types and lots of spares. Never failed me.
AutoMax
Lifetime Supporting Member
I've always assumed the inability to create p/c tags online was due to the impracticality of creating appropriate tags in two processors at the same time. It would be nice if there was a tag-level inhibit function that would get around that limitation.
One reason I prefer p/c tags (although as stated I do use messages) is that they are declared in both processors. How many times have you been at a customers site and done an upload, then had to figure out where data was coming from? P/c helps cut down on that. It certainly doesn't eliminate it, I'm sure everybody has tales of HMI's you can't upload from or OPC servers that no one in the plant knows about. "Now that you mention it, IT did remove an old XP machine the same day this line went down..."
One reason I prefer p/c tags (although as stated I do use messages) is that they are declared in both processors. How many times have you been at a customers site and done an upload, then had to figure out where data was coming from? P/c helps cut down on that. It certainly doesn't eliminate it, I'm sure everybody has tales of HMI's you can't upload from or OPC servers that no one in the plant knows about. "Now that you mention it, IT did remove an old XP machine the same day this line went down..."
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