72 Rockwell Automation Publication ICSTT-RM406J-EN-P - February 2021
Chapter 6 Troubleshooting and Rectifying Channel/Field Faults
• Make sure each retaining tab clips over the printed circuit board to set
the termination assembly in position.
2. Connect the wiring to the screw terminal blocks. Apply a minimum
tightening torque of 0.5 Nm (0.37 ft. lb.) to the terminal screws.
3. Insert the I/O modules (refer to the I/O module installation procedure).
Operation and Maintenance
Plan
An Operation and Maintenance Plan helps to make sure that functional safety
can be maintained after the commissioning of the system. The in-service
operation and maintenance is normally outside the responsibility of the
system integrator, but the system integrator can give guidance and use
procedures to make sure that the persons or organizations accountable for
operation and maintenance can keep the system operating to the specified
safety levels.
The Operating and Maintenance Plan must include the following items:
• Clear definitions of power up and power down sequences. These
definitions must make sure that the sequences never cause resulting
periods when the system cannot operate safely when a hazard is present.
• The procedures for re calibrating sensors and actuators. The
recommended calibration periods must be included.
• The procedures for frequently testing the system at regular intervals,
together with definitions of the maximum intervals between testing.
• Definitions of the overrides to be applied to be able to do maintenance to
the sensors and actuators.
• The procedures for maintaining system security.
Input Module Calibration The Operation and Maintenance Plan must include recommendations to
measure the calibration of controller input modules.
The calibration of each analogue input module must be measured every two
years; the calibration of each digital input module must be measured every five
years.
Planned Maintenance In most system configurations there will be some elements that are not tested
by the system's internal diagnostics — for example, the final passive elements
in I/O modules, the sensors and actuators themselves, and the field wiring.
A regime of planned maintenance testing must be specified to make sure that
any faults, which could ultimately cause the system's inability to fulfill its
safety functions, do not build up. The maximum interval between these tests
must be specified before installation. It is highly recommended the test
interval be less than the Proof Test Interval used to calculate the PFD values.
Field Device Maintenance The Operation and Maintenance Plan must include field maintenance
activities, such as re-calibration, testing and replacement of field devices.
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