DriverMUX Tag Type Properties: Modes Tab
The modes tab allows you to define the operation (and thereby the purpose) of the DriverMUX tag. For each of the three modes, you can select an option from a menu of choices, or you can use a tag or expression to provide external control over the mode.
If defining a tag or expression to control a mode, note that modes are numbered from 0, with the top mode in each list being the 0 mode. Thus, for example, a tag or expression controlling the Selection Mode would need to set the values 0, 1 or 2 for Automatic, Exclusive Primary and Exclusive Secondary, in that order. If the controlling tag or expression goes to invalid, then the last known good value will be used.
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Automatic allows the DriverMUX to switch between the primary and secondary drivers, using rules defined in the other modes.
Exclusively Primary is used when only the driver defined as primary is to be used
Exclusively Secondary is used when only the driver defined as secondary is to be used.
Primary Preferred. In this mode, the primary driver is used for all communication unless it fails, at which point communication is handled by the secondary driver. When the primary driver comes back online, communication is transferred back to it.
Sticky Mode. Similar to Primary Preferred except that communication continues to be handled by whichever driver is currently in use until that driver fails. Upon failure of the active driver, communication switches to the alternate, where it remains regardless of whether communication is restored to the driver previously in use.
Parallel mode. In this mode, both drivers are used for communication on an as-ready basis. Should one driver be busy with a larger communication packet, the other driver will be used for all packets until the first is ready for another packet.
Alternating mode. Both drivers are used in a strictly alternating basis. If the next driver in turn is still busy with its last communication packet, further communications will be queued until that driver is ready for another packet.
Failover mode is of use in a remote application where backup servers are configured to handle communications in the event that a primary server fails.
Switch Drivers First. In the event that communication is lost with the driver currently in use, switch to the alternate driver.
Switch Servers First. In the event that communication is lost with the driver currently in use, attempt to switch to a backup server to re-establish communication with that driver before switching to the alternate driver.