Rockwell Automation T8031 Trusted Valve Manager - Manual (Page 17)

Trusted
TM
Valve Manager T8031
Issue 2 Oct 05 PD-T8031 17
Figure 10 LINEFLT board
2.2. VTEST Function Block
The VTEST function block provides a simplified interface to the valve test functionality of the T8449 –
“Trusted
TM TMR 24Vdc Valve Monitor” module. The Valve Manager utilizes the VTEST function block
to initiate a valve test and record the results.
2.2.1. Operation
The VTEST function block initiates a valve test on the rising edge of the VTS input by driving the VTO
output TRUE. It then uses the MXO output to select the appropriate mux-channel to monitor the test
status (which is read through the MXI and MXD inputs). When the test is complete, it cycles through
the necessary mux-channels to collect the transition times for the test, which it then makes available
through the VT1…VT5 outputs. The VTM output represents the function block’s current mode or test
completion status. On the falling edge of VTS, the VT1…VT5 outputs will be cleared. While no valve
test is in progress, the function block will monitor the appropriate mux-channel to look for a change to
the valve’s Digital Output. Once a change is detected, the function block will wait for the transition
times to become valid (as determined by the T8449 module), then collect the data and present it
through the VT1…VT5 outputs. The VT1…VT5 outputs will remain valid until a valve test is initiated or
a falling edge on the VTP input is detected. The VTP input is the function block’s permissive: while
FALSE, the function block will not initiate a valve test, nor will is be able to collect transition times for a
Digital Output change.