An instance of this service interface function block type provides two radio buttons for the user to enter a boolean OUT value represented as one of two states of a bistate device.

The LABEL1 and LABEL0 inputs provide labels for the true and false values of OUT , respectively.

After initialization, the labels can be changed by the INIT+ service primitive. However, in this case the OUT state will remain unchanged.

An example of the use of an instance of this FB type can be found in the MONITOR device of the CODEC_TEST system configuration, where it is used to provide an ON/OFF switch for the monitoring function.