# Set up connections for the trend

Use the Connections tab to assign up to eight tags, parameters, or expressions to the trend. At runtime, the application notifies the trend object of changes in the value of the tags or expressions.

Tip: | Do not use string tags. To plot historical values, specify tags from the data log model you will be using at runtime. Specify the data log model on the Pens tab. You cannot use expressions to plot historical data. If desired, you can use tags that are in the data log model and tags that are not.

## To set up tags and expressions for the trend

1. In the Graphics Display editor, double-click the trend to open the Trend Object Properties dialog box.
2. Click the Connections tab.
3. Select the pen to assign a tag or expression to.
4. Specify the tag or expression for the pen.
5. If the minimum/maximum value is controlled by a tag or expression, specify the tag or expression in the Minimum and Maximum rows. Tags specified here show in the Controlled by tag text box of the Y-Axis tab.

## See also

Create a trend

Set up the vertical axis for the trend

Options on the Connections tab of the Trend Object Properties dialog box

Best practices for FactoryTalk View Machine Edition trends

Troubleshoot FactoryTalk View Machine Edition trends