Hi,
I've noticed something strange related to Transaction Groups and Publishing/Sampling interval set by the group. Scenario is the following:
- Transaction group with OPC items
- Subscription mode
- Execution time: 250ms
If I check OPC Connection -> Subscription and I select the subscription created by SQL Bridge I see this situation:
and if I check the subscribed NodeID I get this:
So it seems that SQL Bridge set Publishing Interval at half of the execution time (or subscription rate) and sampling interval equal to execution time (or subscription rate) but shouldn't be the other way? Shouldn't sampling interval less or equal than publishing interval?
I'm a bit confused at this point.
Davide
Hi Davide_Bortolini,
The Sampling rate should be slower than the Publishing rate. The server should write to the client at a rate faster than our sampling rate otherwise we can miss data points. Feel free to take a look at the docs below:
OPC-UA Properties:
https://docs.inductiveautomation.com/display/DOC81/Tag+Groups#TagGroups-TagGroupProperties
OPC Connection settings:
https://docs.inductiveautomation.com/display/DOC81/Connections+-+OPC+Connections
That's correct but seems that Trasnaction Group requires a Publishing Interval that is half of requested sampling interval.
As you can see from my example I set TG to a rate of 250ms and then it requested a Pub Interval of 125ms and sampling of 250ms which is the opposite as OPC-UA states.
Or am I reading it wrong?
