National Instruments BridgeVIEW Manual Do Utilizador

Appendix B

Citadel and Open Database Connectivity

© National Instruments Corporation

B-5

These data transforms allow you to directly calculate and retrieve complex 
information from the database such as averages and standard deviations. 
This time saving feature eliminates the need of extracting raw data first, and 
then massaging it in another application to come up with the needed 
information. 

Table B-1.  Data Transform Commands

Min{tag name}

Returns the minimum for tag name 
across the interval.

Max{tag name}

Returns the maximum for tag name 
across the interval.

Avg{tag name}

Returns the average for tag name across 
the interval.

StDev{tag name}

Returns the standard deviation for tag 
name across the interval.

Starts{tag name}

Returns the number of starts (number of 
transitions from OFF to ON) for tag 
name across the interval.

Stops{Datapoint}

Returns the number of stops (number of 
transitions from ON to OFF) for 
Datapoint across the interval.

ETM{Datapoint}

Returns the amount of time Datapoint 
was in the ON state across the interval.

Qual{Datapoint}

There might be gaps in the historical 
data threads in Citadel because of 
machine shutdown or BridgeVIEW 
shutdown. Qual returns the ratio of time 
for which valid data exists for a 
datapoint across the interval, to the 
length of the interval itself. Thus if 
valid data exists for only one-half of the 
interval, Qual would return 0.5.