I'm afraid my input here can only be intuitive, as I don't know the details of how Ignition talks to the OPC client. Intuitively, I would have thought that if Ignition is able to apply a single overriding Subscription Interval in the case of a Leased tag, that it could also be modified to specify a Subscription Interval that depends on the Active/Inactive state. It looks to me like each leased Tag Group creates one or two subscriptions depending on wheter only Active, only Inactive, or Both Active and Inactive tags exist. In my simplistic image of this, it would be a case of creating two parameters where there was one before, and passing the correct parameter when creating those one or two spesific subscriptions. But I defer to your deeper knowledge!
Hi Kevin,
Could you let me know if there is a plan to look into this issue, or maybe you are already working on it. I wasn't quite sure how we left it the other day.
Thanks!
I tried to reproduce but none of our S7 PLCs will return GoodOverload before I start hitting the max monitored item limit.
You could drop a feature request for it but I do think there are technical hurdles that would make this unlikely to happen.
To avoid good overload, you can adjust the cpu ressource (50 percent max) dedicated to communications.
When the publishing interval isn't specified and it's derived from the rate, I think I could relax the enforced range to be [1, 5000] instead of [1, 1000] and still maintain the other subscription behaviors we're interested in... might help a bit.
I'm more inclined to make a change like this for 8.3, along other potential behavior changes, rather than in a point release of a LTS version, though.
Thanks Kevin, relaxing the enforced rate as you suggest would help.
I think the situation I have is that the server nearly manages to publish in time, so the extra 500ms might just be enough. I would be very happy to accept this proposal.
Please advise on what I need to do to update Ignition on my end once this new functionality becomes available.
In parallell, I will submit a change request as indicated earlier in the thread, to allow the publication interval to be set individually for leased and non-leased. But I appreciate this request would have to be considered more carefully and I'm not expecting it to be implemented in the short term.
Thanks mazeyrat,that's a very good tip.
I had been searching for this option but up until now I had not found it.
Here are a couple of links to the Siemens support page where relevant information can be found.
Specifically on the Communication Load parameter:
And here some details about how cycle times are affected:
https://support.industry.siemens.com/cs/mdm/109773506?c=130204919307&lc=en-DE