Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 437)

21 • Set up graphic objects
21-45
•
•
•
• •
Gauges make it easy to see limits
Gauges show numeric values in dial format. They are useful for showing a value in
relation to its lower and upper limits.
For example, a temperature gauge shows the current temperature in relation to its
minimum and maximum extremes. By looking at the position of the needle on the gauge
(pointing left, up, or right), the operator can tell at a glance whether the temperature is
nearer its lower limit, nearer the middle, or nearer its upper limit.
Gauges are used instead of numeric displays when it’s important for the operator to
recognize an abnormal condition instantly, either from far away when the scale on the
gauge isn’t visible, or before the operator has had the opportunity to determine the exact
reading on the gauge. This characteristic of gauges is one of the reasons why they are used
in automobile instrumentation.
Thresholds change a gauge’s fill color
As the needle sweeps higher on a gauge, the gauge can fill the area behind the needle with
a color. The gauge can change its fill color to help an operator recognize abnormal
conditions. The change in color happens when the tag (or expression) value crosses a
threshold you set up for the gauge. For example:
 If the temperature of an oven is lower than required for a recipe, the gauge can show
the temperature in blue.
 If the temperature is in the correct range for the recipe, the gauge can show the
temperature in green.
 If the temperature is higher than the recipe allows, the gauge can show the temperature
in red.
Some people are color blind to red and green, so don’t rely on color alone to establish meaning.