Map item channel to homekit characteristics

I try to add a HomeMatic smoke detector via openHAB to Homekit.

Group		gRM-WZ			"Rauchmelder WZ"							{homekit="SmokeSensor"}
String		RM_WZ			"Rauchmelder Alarm"					(gRM-WZ)	{homekit="SmokeSensor.SmokeDetectedState", channel="homematic:HmIP-SWSD:3014F711A000041709ADFEF0:000A5A49A8007E:1#SMOKE_DETECTOR_ALARM_STATUS"}
Switch		RM_WZ_battery		"Rauchmelder Batterie"					(gRM-WZ)	{homekit="SmokeSensor.BatteryLowStatus", channel="homematic:HmIP-SWSD:3014F711A000041709ADFEF0:000A5A49A8007E:0#LOW_BAT"}
Number		RM_WZ_signal		"Rauchmelder Signal"					(gRM-WZ)	{channel="homematic:HmIP-SWSD:3014F711A000041709ADFEF0:000A5A49A8007E:0#SIGNAL_STRENGTH"}

Homekit’s charecteristic for “SmokeSensor.SmokeDetectedState” expects a switch (0/1) but I get string from the Homematic binding’s item channel.
Is this achievable without writing a rule?

SmokeSensor.SmokeDetectedState accepts String as well. However, it expects the word “Open” for ON/True and everything else will be considered as OFF/False.

maybe you can try to use mapping

I see - will try transformation via profiles. I thought transformation is available just for changing labels.
Thanks a lot!