Rockwell Automation T8449 Trusted TMR 24V dc Valve Monitor Module - 40 Channel - Manual (Page 16)

Trusted
TM
Module T8449
Issue 13 Apr 10 PD-T8449 16
1.11.3. Test Operation
Valve testing is initiated by sending the TEST signal from the user application to the module. Each
signal will initiate a valve test on a per-channel basis (i.e. the application could send the TEST signal to
all channels, several channels, or a single channel at any given time).
A valve test consists of changing the state of the valve (i.e. from Energized/On to De-energized/Off or
vice-versa) and monitoring the positional feedback. When a specific valve position is achieved, the
valve is returned to its original state. If the position is not achieved by a specific maximum time, the
valve is also returned to its original state.
In order to initiate a test, the following conditions must be met:
The module is currently in the Active operational mode.
The control output circuit must be healthy.
The feedback circuit must be healthy (not state 0 or 6).
The reported state of the control output must be either Energized/On or De-energized/Off, and must
match the commanded state. The test will not be initiated if the control output does not have a load, is
in OVC, etc.,. It is also possible that the test will not be initiated just after the commanded state of the
control output is changed, as the reported state may not yet match the commanded state.
The control output must not be forced. This applies only to control outputs with entries in the FORCE
section of the module’s configuration. “Forcing” a control output through the IEC1131 Toolset will not
inhibit valve testing.
A valid, non-zero maximum test time must be specified.
A valid, non-zero end state must be specified.
The module is not currently inside of an Active/Standby changeover operation.
A Test Error will occur if any of the pre-conditions are not met when a valve test is initiated.
During the valve test, the module will record the time difference from the start of the valve test to one
or more changes in the positional feedback levels. The recorded times will be available to the user
application.
Once a valve test has been initiated, it will continue until one of the following conditions is met:
The positional feedback indicates that the desired position has been achieved.
The maximum time allowed for the test has expired.
The commanded state of the control output is changed.
A line fault condition is detected. (i.e. OVC, no-load)
The control output circuit or feedback input circuit is declared as faulty.
The TEST signal is negated (i.e. turned off/de-energized).
The module changes operational modes (i.e. Active to Standby or Active to Shutdown).
An Active/Standby changeover is initiated.
Condition 1 is the only manner in which a valve test will complete successfully. Condition 2 will result is
a valve test failure. All other conditions will result in an aborted valve test.
At the completion of a valve test, the control output will be commanded to its pre-test state if possible.
This will occur regardless of the reason that the test is considered complete. In some cases it may not
be possible to achieve the pre-test state due to line-fault conditions, fault degradation rules, or a
change in module state. (i.e. a control output was Energized/On before initiating a valve test, and
during the valve test the module was placed in Standby. The valve test would abort, but the control
output would be forced to the off/de-energized state because the module is in Standby.)
Here are the usual application logic steps associated with performing a valve test:
Write the maximum allowable valve travel time to the ETIME signal.