Why is TagDebug reading zero for a device in Power SCADA Expert?

Issue
TagDebug is always reading zero.

Product Line
Powerlogic Scada 7.x
PowerScada Expert 8.x
PowerSCADA Operation 9.0

Environment
Reading tags in Admin Mode

Cause
If you are using TagDebug in PowerSCADA to read the real time values for one of your variable tags and you see that the value is zero, then can mean 1 of 2 things:
1- The real time value for this tag is zero.
2- The tag is not communicating which will result a value of zero as well.

Resolution
TagDebug doesn't return the error of #COM when the tag is not reading in PowerSCADA, instead it will return zero. To check if the tag is actually in communications,
you can try to put the tag as a numeric value on the screen. This will show you if the actual value for the tag is zero or #COM. Alternatively, you can try to read the EEHealth tag associated with a device. If the EEHealth tag reads zero, then the device is also in communication loss.