I’ve been struggling with triggered transaction groups for some time. Apparently they won’t work when ‘subscribed.’ In fact when a group is running that has a tag used as a trigger which is subscribed (and reporting bad quality) the quick client won’t subscribe to that same tag either (but it will do a read. Setting the group to ‘read’ instead of ‘subscribe’ seems to help. Should this be like this? I’ve tried working with tech support and have gotten no where. In fact, with some of the ‘beta’ fixes I’ve installed, things have gotten worse.
Can there be two bidirectional items in a transaction group?
When using an expression item, it appears that the expression evaluates after the db write resulting in old data being stored. Is there a fix for this?
To address item 1, we were finally able to reproduce the exact symptoms you describe. Even down to the Quick Client read working but the subscribe not. It has definitely been fixed in version 7.2.6-beta7.
For the other 2:
You can have as many bi-direction items as you want. If the group’s mode is set to bi-directional, all the items (opc items, that is) that don’t override the setting will be bi-directional.
This doesn’t appear to be true, at least at the simple “when are items executed level”. Of course, I’m not calling you a liar, so it could be a number of things- something about how the group is set up, something about what the expressions are doing, or something with the display. What are your expressions doing? Do the reference other tags? If so, where are the tags executed, in the same group, or in SQLTags? Is there a trigger on the group? If easier, right click the group and export to XML and then upload it here. Otherwise, try to describe how they’re configured and how you’re determining that the write is occuring before the update.
Regarding item 2:
If the group is set up as OPC to DB and I add one item that overrides that as bidirectional it works. If I add a 2nd item as bidirectional, only one of these items will work. The other will always show a value of ‘NA’. I’ve uploaded the XML export for this group.
Regarding item 3:
What I was doing was converting a string (from OPC) to a date (to DB). This was a triggered group. The value written to the DB was a conversion of the OPC’s data from the previous trigger (old data) not the current. Since I was having trouble with the triggers I had to do this another way and have since deleted it. I’m sure you could reproduce it fairly easily.
Regarding item 1:
I was told by tech support they would contact me about this yesterday. They never did.
Req_Test.xml (7.68 KB)
I wonder if your problems with multiple bi-directional problems might not be related to your other problems with the contrologix driver. In a different thread I believe there was an issue discussed concerning boolean values- which I think is fixed in the latested update. I’ve set up your group with different OPC addresses on my machine and it works, so it’s not an obvious problem with the groups. So, after you update the driver, see if there’s still a problem, and we’ll go from there.
For the expression items: There was a problem while back in regards to when OPC values were evaluated in groups, which was leading to what you describe. However, that has been fixed for a bit- do you know what version you were trying it on? I mocked up that setup in 7.2.6 and did not notice a problem.
I’m currently running 7.2.6 beta6. I’ll be updating shortly. Let you know what happens.