Howto control tag consume interval on 1756-L61?

[oldnewbee]

Hi all,
I'm new to both Rockwell/AB and to my company. I find a quite complex CLX-5561 software here that needs some debugging / improvement. My problem is:

- I have a CLX based machine with ethernet interface to a PC.
- At PC side, some tags are consumed - but I don't see how frequently.
- I'd like to set an "update interval" of -say- 5 secs. Means: I'd like the CLX to update the data the PC is consuming every 5 secs.

Now the question is: Where would I have to look for parameters controlling this - at CLX side, or rather at PC side? And what symbol names should I look for?

Is there any documentation explaining how to deal with it? I searched through this website and found some hints like "goto AB website and look for 'common procedures'" - but what I found there did not clarify it to me.
Any help appreciated. Thanks.

[rdrast]

PC? As in to an HMI? That would be controlled by the I/O scan settings on the OPC server, not the PLC.

PLC "Produced/Consumed" tags aren't on any interval delay, and are most commonly used for inter-PLC communications.

[oldnewbee]

Hi rdrast,
yes, PC as HMI (mostly). Yes, it's clear that Produced/Consumed Tags are not primarily designed for this - but currently I have to live with it :-)
I will check your hint to OPC server settings.
Thanks very much for the quick reply.

[daba]

Originally Posted by rdrast

PLC "Produced/Consumed" tags aren't on any interval delay, and are most commonly used for inter-PLC communications.

Actually they are.... the configuration for a Consumed tag includes an RPI (Requested Packet Interval) setting (2.0 to 750.0 mS), which specifies how often the tag data is refreshed. Presumably this would work the same if the producer were an HMI on an OPC server, and presumably again the OPC server would specify RPI for data Produced by the controller for an HMI.

[curlyandshemp]

Originally Posted by oldnewbee

Hi all,
I'm new to both Rockwell/AB and to my company. I find a quite complex CLX-5561 software here that needs some debugging / improvement. My problem is:

- I have a CLX based machine with ethernet interface to a PC.
- At PC side, some tags are consumed - but I don't see how frequently.
- I'd like to set an "update interval" of -say- 5 secs. Means: I'd like the CLX to update the data the PC is consuming every 5 secs.

Now the question is: Where would I have to look for parameters controlling this - at CLX side, or rather at PC side? And what symbol names should I look for?

Is there any documentation explaining how to deal with it? I searched through this website and found some hints like "goto AB website and look for 'common procedures'" - but what I found there did not clarify it to me.
Any help appreciated. Thanks.

Consumed tags properties, connections

[oldnewbee]

Hi all,
thanks for your replies.

@curlyandshemp:
yes, this is the way to configure it if you are communicating between PLCs. But I have a PC (Windows) Program being the consuming side. And - as I have learned today - not using OPC but CIP protocol. They have implemented it in C++, and when looking for "RPI" in the source code, I finally found it.
Now I begin to understand how it's working :-)
Thanks very much for your help!
Regards,
oldnewbee

[Eddie Willers]

I am very surprised to hear that your PC application is genuinely using Produced/Consumed Tags. I have never seen that implementation used on an HMI or database connectivity application. Even RA uses ordinary explicit messaging for their FactoryTalk data server.

Can you tell us what company wrote the PC side ? Are they an ODVA member ?

[oldnewbee]

Hi Eddie,

Can you tell us what company wrote the PC side ? Are they an ODVA member ?

well, it's my employer (i.e., colleagues of mine that have been working here before I started my job here). I don't think we are ODVA member. And this software is not intended to be sold as something like a "general purpose library".
Excuse me please, I cannot go into details too deep, but as far as I understand / guess it up to now, this software has grown more or less like this:
- 15 years ago there was need to have a PLC controlling a certain type of process-oriented machines.
- They choosed Rockwell (or AB, at those times?) - for whatever reason.
- Very early it was desirable to have a PC based HMI visualizing process data over time.
- Since I find some basic concepts of CLX software (devices, subscriptions, ...) also in the HMI software, it seems to me that the HMI was originally designed more or less to fit the software / process / communication structure given by Rockwell / AB resp.
- May be this all started at times when there were no external products available solving the needs.
- So, yes, we have this kind of application that surprised you. But since I'm new to CLX programming, I don't know which alternatives are available today, i.e. how / with what means one would implement an HMI for CLX today.
Btw, I actually don't know what "ordinary explicit messaging" means in detail, so I cannot judge the differences :-)
(Up to now I have mainly done C and C++ programming.)

Hope this gives you a clue about my situation.

Regards,
oldnewbee