Hi to everyone! I have a problem with Opc Ua and Leased Tag Group. Inside my project I have too many tags with OPC (about 2900 tags) and this cause the tag quality to be “Good_Overload” when the system drop the scan frequency to ensure the readability of all the tags. I would like to know if there’s some way to decrease temporarily the scan frequency of the Opc Tags. I have tried to use the the leased tag group in order to slow the update of hidden tags, but it doesnt work: I see the tag updating at the same speed when it’s hidden or when it’s displayed.
I use a S7-1500 PLC with the OPC-Server inside. The ignition gateway is the client in this case
If you can see it updating it's leased and therefore subscribed at the fast rate...
What's your lease setup? How are you determining it's working or not?
edit: and what version of Ignition are you using?
I’m using Ignition 8.1.10. I can see the tag not changing its update speed from the value showed in the designer.
I have tried to display a tag on a page through a component but the speed doesnt change. Also I tried to launch a simple project with two pages: one with the tag a the other with without components. From the tag tree inside the designer I see that the tag doesnt change its speed.
Someone have found a solution ?
Thanks
Ignition 8.1.20
Windows 10 pro
Hi at all,
i have make some test :
I created a _jsonUDT document tag that has the time of the plc. In this example structure the SECOND tag is a derivative of the _jsonUDT tag and both have "Defaul_leased" as their Tag Group.
If I put this tag on the page, it is always updated to 1 second, and i don't understand why.
I tried to create the same tag in direct OPC as below:
this tag, on the other hand, is updated 1 second when the page is open, and 10 seconds when it is closed.
How can I solve the problem ? I have many tags that do not need to be updated to 1 second all the time, but only when they are displayed, and I can't even configure all of them as direct OPCs because the PLC server is limited to 10,000 subscriptions, which is why I did all of them document structures with derived tags on it.
Has anyone already had this problem?
I'm pretty sure that deriving from a tag leases the source tag. Sorry.
So if I am not mistaken, the update always remains 1 second even if the derived tag is present on the page. Is this because the parent _jsonUDT (document) tag is not displayed on any page?
Leased tags go fast when any page displays them (binding == lease). They go slow when nothing is displaying/binding them. That is the expected behavior.
ok so there is no method to reduce the control times of derived tags? It would be very useful to avoid overloading the PLC server with requests ...
If this is not possible, is there something in your opinion to solve this problem?
Thanks for the prompt reply.
Leasing works per tag. The document tag is read as a single element. You either read the whole thing or you don't. If any expression includes that document tag to produce some result, it is leased. So it will read fast.
Consider getting rid of the derived tag by moving the read expression to expression bindings in your display(s). Then the document tag will be read fast or slow based on whether anything is displaying from it.
In other words, I see your setup working as designed. You simply haven't configured your data flows to take full advantage of what leasing can do. And avoiding what it cannot do.
If you run out of OPC items because of an arbitrary limit in the PLC, you might need to spend $$ on a more capable device or OPC server. Or split the application into multiple PLCs. Or switch to a PLC brand that doesn't [expletive] you this way.
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Ok thanks a lot for the explanation. 