Value Indicators for Analog Input Tags

Value indicators are typically associated with analog input tags. Because the value of an analog input tag is a continuous numeric value, those methods often employed by digital input tags (such as a changing color to indicate value) are not appropriate. Analog values are better suited to changing numbers, or to suitable bitmaps like bars and gauges that can clearly portray the exact value of the tag and its related equipment as it changes.

For example, you could portray the level of fluid in a tank or well by:

•      A changing number displaying the exact level value to the decimal point;

•      A bar that changes in size vertically or horizontally to display the exact level value; or

•      A gauge whose needle displays the exact level value to the decimal point.

Again, VTS provides you with a wide variety of easily configurable drawing methods suitable to the type of tag and your requirements.

For many analog inputs, it is useful to draw the same tag in a number of different ways so that the value is clearly portrayed. For example, the use of a numeric display in combination with an image of a meter or a changing bar gives operators a both a visual estimation of the value, along with the actual value. Consider the example in Figure 6:

Figure 6

In the above illustration, not only do we get a clear visualization of the level of water in Tank 2, but a numeric value is also provided to help us know the exact value to the decimal point.