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

Trusted
TM
Module T8449
Issue 13 Apr 10 PD-T8449 40
5. Fault Finding and Maintenance
5.1. Fault Reporting
Output module faults are reported to the user through visual indicators on the front panel of the module
and through status variables which may be automatically monitored in the application programs and
external system communications interfaces. There are generally two types of faults that must be
remedied by the user: external device and/or wiring and module faults. External device and/or wiring
faults require corrective action in the field to repair the fault condition. Module faults require
replacement of the module.
The TMR 24Vdc Valve Monitor also reports valve test failures, which are considered device/wiring
faults.
5.2. Field Device and Wiring Faults
By measuring the output channel voltage and current, the module automatically detects field-wiring and
load faults. When a field signal fails open circuit, short circuit or there is not field supply voltage
connected, the output status indicator will display the configured LED mode, the corresponding output
state will be reported and the line fault status for that channel will be set to ‘1’. All other output
channels will be unaffected, except in the case of common cause wiring and supply voltage faults in
the field.
The field output voltage and current variables can be monitored to determine the actual operating
conditions of each output channel. This additional information assists the user in determining the
specific type of wiring fault.
Valve test failures are detected when a valve test is in progress. If a field-wiring or load fault is detected
during the test the test is aborted, the device is placed in it’s last commanded state, and the module
reports a field fault. The module will also report a field fault if a valve test is aborted because the
desired feedback state was not reached within the specified time limit.
Once the specific field-wiring fault has been identified and corrected, the output status variables and
output status indicator will display the normal on/off status of the field device.
5.3. Module Faults
Extensive diagnostics provide the automatic detection of module faults. The TMR architecture of the
output module and the diagnostics performed ensure the validity of all critical circuits. Using the TMR
architecture provides a Fault Tolerant method to withstand the first fault occurrence on the module and
continue normal output controls without interruption in the system or process. Faults are reported to
the user through the Healthy status indicators on the front panel of the module and through the INFO
and HKEEPING variables. Under normal operations all three Healthy Indicators are green. When a
fault occurs, one of the Healthy Indicators will be flashing red. This indicates that the module should
be replaced.
Module replacement activities depend on the type of spare module configuration chosen when the
system was configured and installed. It is recommended that this condition is investigated, and if the
fault is within the module, it should be replaced.
5.4. Dedicated Standby Slot
For a Dedicated Standby Slot configuration, two adjacent slots in a Trusted TM Chassis are configured for the
same output module function. One slot is the primary slot and the other slot is a unique secondary (or spare)
slot. The two slots are joined at the rear of the Trusted
TM Chassis with a doublewide I/O Interface Cable that