Trends

A trend is a set of variables brought together to be watched as one. Gather a pump’s temperature, pressure and current into a single trend and the operator sees all three on one chart, on the same time axis.

The screen is in two parts: the list of trends above, and the selected trend’s Trend Tags panel below.

Trend fields

Field	Description
Name	The trend’s name, max 100 characters
Description	Description, max 255 characters
Period (ms)	The sampling period, in milliseconds
Order	Where it appears in lists

The period has a floor

The period cannot go below 100 ms. That is the platform’s general sampling floor: no installation produces a sample more often than that. Entering something smaller does not make the chart faster.

Tags

A trend is made of the tags added in the Trend Tags panel. Each tag carries a variable and how that variable is drawn on the chart:

Field	Description
Name	The tag’s name
Description	Description
Variable	The variable to draw
Status	Whether the tag is active
Min Scale / Max Scale	The axis floor and ceiling
Color	The line colour
Thickness	The line thickness
Grid Thickness	The grid thickness
Hide Value Axe	Hide this tag’s value axis
Order	Drawing and listing order

Scale and axis go together

When one chart carries two variables with very different units (°C and bar, say), an axis that suits one makes the other unreadable. Use Min Scale / Max Scale to seat each tag in its own range, and Hide Value Axe on the secondary one to keep the chart uncluttered.

Related

• Trend Graphic — where a trend is drawn
• Variable History — the same data as a table
• Variables — the logging configuration