Rockwell Automation T8031 Trusted Valve Manager - Manual (Page 22)

Trusted
TM
Valve Manager T8031
Issue 2 Oct 05 PD-T8031 22
The following logic would be used to drive the “_VTP” tag to prevent initiating a test:
Figure 16 Valve Test Permissive Logic
Note the use of the “_VTO” tag as a qualifier for the “_VPS” logic. This is important, as the main
purpose of a value test is to change the valve position state. If a test was initiated and the “_VTO”
qualifier was not present in the above logic, the test would be aborted as soon as the valve position
state changed.
2.3.2. End State and End Time Tags
The variables used for the End State (or “_EST” tag) and End Time (or “_ETM” tag) values are used by
the Valve Manager even though they are not connected to the VTEST function block. The “_EST” and
“_ETM” tags should be connected so that they drive the “_ESO” and “_ETO” variables respectively.
Figure 17 End Time and End State Logic
When a valve test is initiated through the Valve Manager, the values for End State and End Time as
configured in the Valve Profile for that valve within the Valve Manager are used. That is, the Valve
Manager writes the configured values to those variables before initiating a test. The End State and
End Time variables are also used by the Valve Manager to clear the transition times after a change to
the valve’s Digital Output has been detected by the VTEST function block. It does this by writing an
invalid value to both values (zero), then initiating a valve test. The VTEST function block will report a