Allen-Bradley ControlLogix 5570 - Thermal Monitoring and Thermal Fault Behavior

Rockwell Automation Publication 1756-RM100F-EN-P - October 2018 81
Replacement Considerations with CompactLogix and Compact GuardLogix Systems Chapter 3
Thermal Monitoring and
Thermal Fault Behavior
The controllers monitor internal module temperatures and respond as the
temperature increases.
Figure 15 - Thermal Fault Behavior
Threshold for controller to declare a `Hardware Preservation
Fault’, and reset the module and disable power.
In the disabled power condition, only the OK status indicator is
illuminated, and it is red. The module does not apply power
until it has cooled below the Hardware Preservation Hysteresis
limit. The module then enters fault mode, records the fault in
the major fault log, and displays `CPU Temperature Fault’ on
the front panel.
Threshold for controller to declare a `CPU Temperature Fault’
major recoverable fault. If a fault handler does not clear the
fault, then the module enters fault mode, records the fault in
the major fault log, and displays `T17:C34 CPU Temperature
Fault’ on the front panel.
Threshold for controller to declare a `T17:C35 Controller internal
temperature is approaching operating limit’ minor fault and set
the Diagnostics minor fault bit.
The fault is recorded in the minor fault log, but is not displayed
on the front panel. If the temperature returns to an acceptable
range, the Diagnostics minor fault bit clears, but the minor fault
record remains.
Power to the
controller is
disabled
Hardware Preservation
Hysteresis Limit
Power does not
become enabled
when in this range
All power to the controller is disabled except
to run the red OK status indicator and
monitor the temperature.