Understanding Multi-Control

When a Controller triggers a Multi-Control operation, easy eXtended Operator Station (ezXOS) tries to queue each control command into the Omnicomm queues. If all control commands are queued successfully, the Multi-Control command is considered successful, and all queued commands will eventually be executed by the Omnicomm process. The application does not wait for each individual control command to complete.

If one of the control commands fails to be queued (for example, a "no-command" tag may be attached to the point), the application continues to queue the rest of the control commands. When all control commands are processed, the application alerts the Controller about each failed control command and continues to queue the remaining commands. Controllers can verify the completion of individual control commands through the following windows:

• Alarm Summary window

• Event Summary window

• MultiControlGroup Control dialog box

Whether or not queued control commands are sent to the Remote Terminal Unit (RTU) depends on the timing of RealTime service failover or mode switch. If all control commands are queued successfully before a service failover or mode switch, the application indicates success to the Controller. If a RealTime service failover or mode switch happens before, or in the middle of, the queuing of control commands, the application indicates failure to the Controller. If some control commands are queued, they may or may not be sent to the RTU, depending once again on the timing of RealTime service failover or mode switch.

The key difference between Multi-Control command and single point control command is that Multi-Control command can queue up multiple control commands in one control operation. In contrast, single point control command always queues up one control command.