Creating a Variable Triggered Trend Log

You create a variable triggered trend log to record the variable according to the changes of an associated trigger variable.

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The variable triggered trend log records the variable when the conditions of the associated trigger variable are met. Use this type of trend log when the log interval is scheduled to log monthly or yearly, or when another device is used to trigger the log.

For example, in the figure below, the variable triggered trend log records a variable every time the associated trigger variable, for example, a switch, changes to true. The records are printed in a trend chart. Notice that the variable triggered trend log records the variable without any regard to time or delta.

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Figura: Variable triggered trend log schematic

You can configure the trend log to collect data when the trigger value changes to True, changes to False, or All changes.

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Figura: Trigger variable changes to true

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Figura: Trigger variable changes to false

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Figura: Trigger variable all changes

To create a variable triggered trend log

In WorkStation, in the System Tree pane, select the folder or SmartStruxure server where you want to create the trend log.
On the File menu, point to New , and then click Trend .
Select Variable Triggered Trend Log .

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In the Name box, type a name for the trend log.
In the Description box, type a description.
Click Next .
In the Logged variable box, enter the variable you want to log.

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Click the Set unit button

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.
Select a unit for the trend log values.

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In the Prefix box, select the prefix of the unit.
Click Select .
In the Trigger variable box, enter the variable that triggers the log.
In the Trigger condition box, select Change to true to log the variable when the trigger variable changes to true.
In the Log size box, select the number of records to be stored before old records are overwritten.
In the Available trend storage box, check that the available number of records is not exceeded.
In the Clear when enabled box, select True to clear the trend log every time the trend log is enabled.
Click Next .
In the Extended Trend Log box, click the Browse button

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to create an extended trend log and connect it to the trend log.

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In the Trend Log List box, click the Browse button

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to create a trend log list and connect it to the trend log.
In the Trend Chart box, click the Browse button

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to either create a new trend chart or connect the trend log to an existing trend chart.
Click Create .