DANGER Configuration Changed

When new configuration data is applied to an I/O module, the module will accept the new configuration regardless of the number of controllers consuming I/O from that module. Every controller sharing the I/O module will begin receiving input data based on the new configuration. Care must be taken in multiple-owner configurations to ensure that a configuration change appropriate for one controller does not have an adverse effect on the control program in another controller. In single-controller configurations, these considerations are not necessary.

When configuration is changed online in multiple owner systems (where multiple controllers are configuration owners for a single input module) the input module accepts the configuration as a temporary configuration. In its temporary configuration state, the input module will disallow any new connections to be formed including reestablishment of a lost connection. Thus, if any controller loses its I/O connection subsequent to an online reconfigure it will be unable to reestablish that connection. The input module remains in the temporary configuration state until it loses its connections with all configuration owners. This can occur in one of several ways:

Reset the module to break all connections. Not recommended if the module is configured to be a critical module as the controller will fault. This can be performed via the Module Info tab under the modules properties dialogs.
Inhibit the module connection on all controllers owning configuration for that module and then uninhibit all the connections. This can be performed via the Connection tab under the modules properties dialogs and can also be performed from this prompt dialog.

To prevent other owners from receiving potentially erroneous input data and avoid the temporary configuration state, as described above, the following steps are recommended.

For any of the owner controllers, in the software, inhibit its connection to the input module. This can be done ahead of time from the connection tab under module properties but is most easily done by checking the Inhibit checkbox in this confirmation dialog that is provided when the reconfiguration is attempted.
Make the appropriate configuration data changes to the controller via the software.
Repeat steps 1 and 2 for all owner controllers, making the
exact same changes
in all controllers.
Uninhibit each controller’s connection to the input module. This can be performed via the Connection tab under the modules properties dialogs.

Why all owner controllers must have the same configuration

In multiple owner systems where multiple controllers are configuration owners for a single I/O module, the configuration in each controller must match. When configuration data does not match, scenarios exist where the I/O configuration may revert back to the configuration stored in one of the other controllers and/or where one of the controllers’ I/O connections may fault. These scenarios include:

resetting the I/O module
power-cycling the chassis
removing and inserting the I/O module under power
cable loss and reconnection
power-cycling the controllers
any other operation that could result in a communications loss and subsequent reestablishment

When configuration is changed to one controller in a multiple-owner configuration, it is your responsibility to manually apply the identical configuration to all other controllers that own configuration data for that I/O module.

Select:	To:
Inhibit Connection before applying configuration change	inhibit the connection to the module before changing the configuration
OK	to reconfigure the module (if connection is not inhibited) or to save the configuration (if connection is inhibited)
Cancel	cancel the operation