Action Item Question

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1

I think I already know the answer to this question but thought I would ask the GURU’s here.

I have an action item which is writes to a table in Microsoft SQL. This action item is in a group which is triggered and the trigger is set to ‘Change of state’. So with that my questions are:

  1. The action item that writes to the SQL table will only write to the SQL table if the state of the trigger has changed. Would this be correct?

  2. If the action item has stuck in the on position, you see it is set up that on the first pass it sets the action item to a 1 then on the second pass it sets it to a 0 (zero), kind of follows the trigger, but occasionally it sticks in the on position. Anyway if the action item is stuck on but the trigger has not changed then the value of the action item is not written to the SQL table. Would this be correct?

  3. So if this action item sets the SQL table, but the action item has not reset, and the trigger has not occured, the value that was written by the action item stays in the SQL table. And if this value in the table is sent to the PLC units on the production floor and then I have the PLC clear this, the value in the table will change, so long as I have the correct data setting in FSQL, but it will not show the change in the action item. Would this be correct?

Thanks and have a great day.

2

mrtweaver,

This all depends on your trigger and action item settings. For a group that triggers on a value change, action items will only evaluate (calculate and write it’s value) every time the group trigger changes. To answer your questions:

  1. Yes, the action item only writes once each time the trigger value changes as long as the action item’s “Ignore group trigger settings” box is not checked.

  2. Yes, if the value of the trigger does not change and the writing action item is not ignoring the trigger, then the action item won’t write.

  3. Yes, the action items only put information into the database (unless it is an SQL query), so any change made to the database won’t show up in the action item. But you can have another action item that ignores the trigger and selects the value that the previous item is writing to.