FactoryTalk SE Network Database Polling

I am developing an HMI interface which displays information from a PLC, but it is also necessary that I obtain additional information that is currently stored in a SQL database. There are no plans to make this information available in the PLC. How would one set up a SE Network application that will poll this information on a given interval and update as appropriate? Ideally it may work to have string tags that have their values updated and then used in the clients.

I am relatively new to this, so if there are better ways to do this I am open to explore and try them.

Thanks

You need to create a cached, always updating display (it is your option to hide it away somewhere) running VBA conde to access the database.

I STRONGLY advise against timer events in VBA, so you would be best to run your polling timer in the PLC, and have a numeric display on the FTView SE screen watch it. Enable the numeric display for "VBA Control", and run your database poll from the "OnChange" event.

I've implemented a strategy as you have suggested--I have been trying to do some tests to better understand how the client/server works in the FactoryTalk model (having trouble finding the details I want in the manual). If I make the clients automatically open the cached screen on start, does the server only maintain one global copy of this screen that is the one the latest client opened?

Put another way, if I have five clients open that have the database query dialog open and hidden, is there really only one of these open on the server that is actually querying the database? The cached display is simply querying the database on a given interval and then updating the tags--the clients use these tags on other displays.

Ahh... That.
In my VBA for database stuff, I only let it run on the server. I do that by only allowing the logging if the computer name matches the server name. Sort of a pain, but it works.

How is it that you run displays on the SE network server?

tatsumasa said:

How is it that you run displays on the SE network server?

Click to expand...

I always have a client on the server. Barring that, pick and always on client, and use that for the database interaction.

Ah I thought that you might say that--sounds expensive to have another client for that! I'll have to come up with some sort of scheme to get only one of the clients to do it, maybe there is a way to do a connected client count, or the single always on client as you suggested.

It seems the more I research about FT the more I dislike... like the clientside VBA. I was hoping to keep all the code running on the server with the database to speed up access times, but the only way to get this now would be that extra client

Thanks for the information.

Initially, I was disapointed about VBA code running on the client vs. server as in RSView32. But the VBA in SE is much more powerful than the one in REView32. I have an always hidden screen that runs all the VBA code that needs to be running all the time. I then have only one of the clients load this screen at startup.