Question about group refresh rate

If a group’s refresh rate is set to 30 seconds, does it start timing when you start the group, or when it sees the group trigger go high?

I’d like to have a group log data points every 30 seconds when a bit is high. I’d rather not make a timer in the PLC to accomplish this. But it is important for FSQL log as soon as the process starts.

The update rate is the rate at which the group runs and evaluates its state. That means if you have a group set to run at 30 seconds with a trigger, every 30 seconds the state of the trigger will be evaluated and the group will log if appropriate.

So, with the basic settings, when your trigger goes high it will take sometime between 0 and 30 seconds for the first execution, and then will log every 30 seconds after that. Are you saying that you need the first log to occur sooner? Usually if you’re logging at a 30 second rate it doesn’t really matter if it takes up to 30 seconds for the first record, but if it does in your case it may be possible to come up with a more advanced trigger scenario using action items.


I get what you’re saying. That’s actually how I was thinking it worked.

What we’re thinking about doing is creating a timer in the PLC that sets a bit high every 30 seconds. We’ll use that as the group trigger and have the group reset it low when it’s done. In our case it’s very important to take a snapshot of the data at the very beginning of each process. We’ll also set the trigger high when the process is complete so we get one final reading.

Thanks. Once again you’ve answered my question.