Learn how to manage the trigger state and reset the trigger after execution.

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[00:00] In this group I have a Boolean Tag that I want to use as my trigger. So I've set it to read only. On the trigger tab I'm able to trigger and select the item. In this case I wanted to trigger on the true condition. Which for Boolean's is the above zero condition. In this particular case I want to select the reset trigger after execution flag What this means is that each time the group executes and sees the true condition it will write the opposite value of the true condition back the tag upon successful execution. So for example in this case when the tag goes to true the group will run and having completed successfully it write a zero back to the Boolean. If I had selected trigger on zero successful execution would write a true value. So let's see it in action if I'm able to group and come back to my data base browser I see that currently I have no rows. As soon I trigger the tag a row is inserted but more importantly we see that my trigger value has been written back to zero. This mechanism has many useful applications. In this case where I'm using the memory tag it means that I can trigger the groups execution from other parts of the system. For example, I may have a button on the screen that writes a value to this tag telling the group to execute. Another common situation is to have what's known as a PLC watchdog where the PLC is setting this bit high and the group is automatically resetting it in order to prove that the group is still running. This can also be used for flow control as the PLC may load data into registers set the bit high and then only load new data when it sees that the group has executed successfully indicated by the trigger reset. Another way to accomplish this could be the success handshake but we'll cover that in another video.

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