This function block allows multiple functions for a switch. It is similar to the Stairwell light switch and following a trigger provides an adjustable pulse at the output. It includes a permanent on with a timeout and a warning function.
After a rising edge at input Tr no more than time TT, the output Q is activated for the set duration TH. If there are more rising edges at Tr before the duration is up the output Q is toggled.
Like the Stairwell light switch there is a warning signal built into the Multifunction switch. The duration of how long before the lights turn off is set by TW, and the duration of the flash is set by WT. For example, the lights go on for 20 minutes (TH), there is a warning flash of 3 seconds (WT) 30 seconds (TW) before the lights turn off. This could be useful in industrial corridors etc.
If the pulse at Tr is longer than the parameter TT then the lights are switched on permanently. The output Q will remain active until it is either reset by R or another pulse shorter than TT at the input Tr.
If Dis is enabled the output Q is locked and stays in its currently output state. This could be used as a child lock for example.
The block can be set to be retentive, this is done by clicking on the battery symbol to set the red NOT dot on the block (input is by default inactive).
The multifunction switch is really useful for boosting things like towel rails, heating, hot water, or lights (for example a porch light). For example imagine having a 3 way switch in your bathroom (no problem in the UK because the switch is now 24V). The top switch could scroll through light scenes, the bottom could turn the lights off and the middle button could be a boost for the towel rail.
The image below shows how you would configure this, it is really useful to use multiply to turn hours into seconds as this makes much more sense when programming but also if Duration on constant was instead a virtual input as a slider that showed on the user interface this would need to be in hours not seconds!