Table 35 - Controller Module Replacement - Honeywell HC900 User And Installation Manual

Replacing the Controller Module
Removing and replacing the Controller Module requires that that the source of AC power is removed from
the rack. Removing power from the Controller rack has the following consequences:

All control action stops

All power to all I/O modules in the rack is lost; hence all control outputs to the process are lost. Because
external power connected to terminal boards (from or to field devices) will still be present, it is essential
that field devices are maintained in a safe condition during replacement procedures.

Control to all I/O expansion racks is lost. If power is available to the expansion racks, outputs go to
configured Failsafe values.
C75 module

Does not impact the other C75 CPU module, which will continue to control the process

Contains start-up diagnostics after replacement to verify proper operation

If there is a Lead Controller, the configuration database is automatically copied from the Lead to the
newly replaced C75 CPU module.
Before replacement:

(If possible), upload and SAVE a copy of the configuration, or ensure that a previously saved copy of the
current configuration is available.

(If possible), bring the process to a safe and orderly shutdown.
Step
1. If a process is currently in operation, bring it to a safe and orderly shutdown.
2. Using an external (user-supplied) switch, disconnect the power supply in the Controller rack from the
site AC power source.
3. Observe where communications cables are plugged into the Controller Module, and if necessary, tag
them to identify their functions. Unplug all communications cables.
4. At the top and bottom of the module, loosen the captured screws that secure the module in the rack,
and remove the Controller Module from the rack.
5. Ensure that you set the S1, S2, and RS-485 terminal dip switches as applicable.
6. Ensure that the new Controller Module is properly aligned with the slot guides, insert the new Controller
Module in the rack, and secure it in place with the captured screws at top and bottom of the module.
7. Re-install communications cables.
8. Using the (user-supplied) switch, re-connect site AC power to the rack.
9. If using the Ethernet port for configuration, use the Designer software to set the proper network
address.
10. Download the configuration.
11. Set the Real-Time Clock.
12. If all status indications are green, power may be restored to the I/O modules per the application's
procedures.
Revision 6
21 April 2017
Table 35 – Controller Module Replacement
HC900 Process & Safety Controller User and Installation Manual
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