Decommissioning a controller takes it out of service. When you decommission a controller, all the information in the controller is erased. You should not unassign modules when you decommission a controller because these assignments can be restored through a download after you commission the controller.
Whenever you need to remove or a controller for service, or to move it to a new location on the control network, you should decommission the controller.
When you decommission a controller, the controller icon and all its database information remains visible in the Explorer. Database information includes all the configured cards, card types, channel types, and all the modules assigned to the controller. You can restore all of this information by commissioning the controller and selecting the Download Controller Node.
You can potentially lose online data if it is different from the information in the controller. For example, if you have made online changes to a module from Control Studio, you lose this data when you decommission the controller unless you first upload the changes into the database.