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LESSON LIST
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2:56About Transaction Groups
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4:42Types of Groups
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2:48Group Update Rate
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3:17Item Types
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3:19Tag References vs. OPC Items
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2:58Expression Items
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4:03SQL Query Expression Items
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3:14Run Always vs. Triggered Items
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3:04Hour and Event Meters
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3:17Resetting Hour and Event Meters
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2:50Trigger – On Value Change
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2:21Trigger – While Condition is True
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1:42Trigger – Rising Edge (Once)
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2:12Trigger – Reset Trigger
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1:50Trigger – Handshakes
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LESSON
Trigger – Handshakes
Description
Learn how to use the handshake mechanism to communicate successful and failed executions to other parts of the system.
Video recorded using: Ignition 7.9
Transcript
(open in window)[00:00] When a transaction group executes, one of two possible outcomes can happen. Either the group completes successfully or an error prevents successful execution. Both of these cases can be communicated to other parts of the system through the handshake mechanism. Handshake's on the Trigger tab. And there are separate settings for success and for failure. Each time the group completes successfully, the item set to the success handshake will be written with the value specified. If something occurs in the group that prevents execution, the failure handshake will be written. The items used for the handshakes must come from inside of the group. So we can either use tag references or we could use OPC items set to read only if we didn't have a reason to store them in the database. For example, we might choose to write a one in the group that's successful and a two if it fails. Since I've used a tag reference here, other parts of the system can watch and monitor what is going on in the group. It's important to note that the success handshake is very similar to the reset trigger condition. So if you're using a trigger with the reset event, it's not necessary to use a success handshake. Or, you may choose to use it in order to notify a different tag or different part of the system that the group has completed successfully.