User Manual

9.170 Device-Switcher

The Device-Switcher logical device lets you access one of two identical physical devices through a common device name. An 'A' / 'B' selection parameter lets you switch between the two devices.

The Device-Switcher device mimics almost completely the actually selected device. Merely the configuration parameters of the device are not passed through, the Device-Switcher always shows its own configuration parameters instead of the parameters of the device it actually mimics.

Beside selecting the device to mimic by the 'A' / 'B' configuration parameter, the Device-Switcher offers a function to watch a given parameter (e.g. a protection switch location) and to select the device depending on the value of this parameter.

Device window pages

The Device-Switcher itself has no device window pages. It shows the device window of the device it actually replicates.

Configuration parameters

At the maintenance page of the device window there are a couple of configuration parameter which must be set to interconnect the Device-Switcher device with the devices it shall mimic.

parameter	description
deviceA	The name of the device to mimic if 'position' is 'A'
deviceB	The name of the device to mimic if 'position' is 'B'
position	Selects the device to mimic, one of 'A' or 'B'
switchId	If this is not empty, the Device-Switcher will watch the parameter with this ID and select the device to mimic based on the content of this parameter
switchPosA	If the value of the parameter addressed by 'switchId' changes to this value, the Device-Switcher changes to position 'A'
switchPosB	If the value of the parameter addressed by 'switchId' changes to this value, the Device-Switcher changes to position 'B'

Remarks

Unlike other configuration parameters the parameters 'mode' (OPERATIONAL/OUT-OF-SERVICE) and 'verbose' refer to the device the Device-Switcher actually mimics.
The Device-Switcher works best with two devices which are identical, i.e. the use the same device driver and have the same options installed. You can use different device types with the Device-Switcher, but you have to be aware that some information like the device screen selected will not change automatically when you swap devices.
The Device-Switcher does not work with devices using the drivers Gate-Array and Proxy-Device as these tweak parameter definitions in a way that is compatible to the Device-Switcher.
Device-Switchers may not be nested. This is for the same reason as with the device types above, the Device-Switcher does not have its own parameters, it only forwards message from an to the the selected device.

Variables defined by this device driver

name	type	flags	range
info.driver	TEXT	R/O	StringRange R/O
config.deviceA	TEXT	SAVE SETUP	StringRange
config.deviceB	TEXT	SAVE SETUP	StringRange
config.position	CHOICE	SAVE SETUP	EnumRange (A B)
config.switchId	TEXT	SAVE SETUP	StringRange
config.switchPosA	TEXT	SAVE SETUP	StringRange
config.switchPosB	TEXT	SAVE SETUP	StringRange