Example Carbon Monoxide

Properties

Available Properties

To have a Carbon Monoxide Sensor appear in the Home.app showing a peak level you can setup the flow as carbon monoxide is detected. The following characteristic properties are available: To have a carbon monoxide sensor appear in the Home app, the CarbonMonoxide service is used. Required value is CarbonMonoxideDetected, there will be a simple example and detailed example included below. Characteristic Properties are not needed for this setup, the values will be updated in the Home app based on what is being sent from your sensors.

Characteristic	Optional/Required	Characteristic Properties (to enable property)
CarbonMonoxideDetected	Required
CarbonMonoxideLevel	Optional	{"CarbonMonoxideLevel":true}
CarbonMonoxidePeakLevel	Optional	{"CarbonMonoxidePeakLevel":true}
CarbonDioxideLevel	Optional	{"CarbonDioxideLevel":true}
CarbonDioxidePeakLevel	Optional	{"CarbonDioxidePeakLevel":true}

Details

Characteristic	Format	Accepted Values	Notes
CarbonMonoxideDetected	uint8	0, 1	0: levels normal, 1: levels abnormal
CarbonMonoxideLevel	float	0 - 100	Sets current carbon monoxide level in PPM
CarbonMonoxidePeakLevel	float	0 - 100	This is the peak level detected. It could be used as a 24-hour maximum or an all time maximum depending on the Node-RED programming.
StatusActive	bool	true/false	{"StatusActive":true} / {"StatusActive":false}

Example

These examples are meant to be copied into your Node-RED system and adapted to your setup.

Please note: Different from other HomeKit services (e. g. temperature sensor) the Home.app is not showing the carbon monoxide level on the device icon. To view the current value you have to open the preferences of the device in the Home app or ask Siri. This works as designed by Apple and can't be changed.

Simple Carbon Monoxide Sensor

This example is a simple Carbon Monoxide sensor that is only ever "triggered" or "normal". The msg.payload going in is either {"CarbonMonoxideDetected":1} or {"CarbonMonoxideDetected":0} where 1 is "carbon monoxide detected" and 0 is "normal conditions". Use this example as a starting point for simple alarms that do not send detailed levels.

Copyable Node-RED flow:

[{"id":"ac79f4f4.906df8","type":"homekit-service","z":"54339415.36f384","bridge":"d334490b.40dac","name":"Simple CO","serviceName":"CarbonMonoxideSensor","topic":"","manufacturer":"Default Manufacturer","model":"Default Model","serialNo":"Default Serial Number","characteristicProperties":"{}","x":670,"y":800,"wires":[["933cc1a6.dc8c98"]]},{"id":"7fe97674.cbc19","type":"inject","z":"54339415.36f384","name":"Not Detected","topic":"","payload":"{\"CarbonMonoxideDetected\":0}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":470,"y":820,"wires":[["ac79f4f4.906df8"]]},{"id":"933cc1a6.dc8c98","type":"debug","z":"54339415.36f384","name":"CO Debug","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":850,"y":800,"wires":[]},{"id":"3efd37a6.392f78","type":"inject","z":"54339415.36f384","name":"Detected","topic":"","payload":"{\"CarbonMonoxideDetected\":1}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":480,"y":780,"wires":[["ac79f4f4.906df8"]]},{"id":"d334490b.40dac","type":"homekit-bridge","z":"","bridgeName":"Example Bridge","pinCode":"111-11-111","port":"","allowInsecureRequest":false,"manufacturer":"Default Manufacturer","model":"Default Model","serialNo":"Default Serial Number"}]

Full Featured Carbon Monoxide Sensor

This is an example of a carbon monoxide detector that reports the current amount of carbon monoxide in the air as parts per million (PPM). A threshold level of 35 has been set as the "alarm level". This level was chosen because it is the limit of what OSHA has decided is unsafe for 8 hour exposure. Please adjust to the threshold you would like in your system.

There are three inject nodes in this example:

The Alarm inject node will cause an alarm to trigger in the Home app. The flow will cause 2 values to be sent to HomeKit immediately, the CarbonMonoxideLevel and {"CarbonMonoxideDetected":1}. If the new level is higher than the previous peak level (saved in the function as a context variable) then an additional CarbonMonoxidePeakLevel message will be sent. The alarm inject button also starts a 1-minute timer before a {"CarbonMonoxideDetected":0} message is sent; this message serves to turn off the Home app alarm.

The Non Alarm inject node will simply update the CarbonMonoxideLevel reported and the CarbonMonoxidePeakLevel if it is a new high value since the Reset has been pressed. No alarm will be triggered.

The Reset inject node will send a value of 0 to both CarbonMonoxideDetected and CarbonMonoxidePeakLevel - used to clear the system after alarms have been delt with and carbon monoxide sources have been stopped.

Copyable Node-RED flow:

[{"id":"64c75b4e.98b30c","type":"trigger","z":"54339415.36f384","op1":"","op2":"{\"CarbonMonoxideDetected\":0}","op1type":"pay","op2type":"json","duration":"1","extend":true,"units":"min","reset":"","bytopic":"all","name":"1 minute alarm","x":640,"y":640,"wires":[["72bdfc6c.5a604c"]]},{"id":"c756aa6.24b10d8","type":"function","z":"54339415.36f384","name":"Peak Level and Alarm","func":"var co = context.get('co')||0;\nvar NEWco;\nif(msg.payload==\"RESET\"){\n    co=0;\n    context.set('co',co);\n    msg.payload={\"CarbonMonoxidePeakLevel\":co,\"CarbonMonoxideLevel\":co};\n    return [msg,null];\n}\nvar alarm={};\nalarm.payload={\"CarbonMonoxideDetected\":1};\n\nif(msg.payload.CarbonMonoxideLevel){\n    NEWco=msg.payload.CarbonMonoxideLevel;\n    if(NEWco>co){\n        co=NEWco;\n        context.set('co',co);\n        msg.payload={\"CarbonMonoxidePeakLevel\":co};\n    }\n    if(NEWco>=35){\n        return [msg,alarm];\n    } else {\n        return [msg,null];\n    }\n}","outputs":2,"noerr":0,"x":360,"y":620,"wires":[["72bdfc6c.5a604c"],["64c75b4e.98b30c"]]},{"id":"72bdfc6c.5a604c","type":"homekit-service","z":"54339415.36f384","bridge":"d334490b.40dac","name":"CO Detector","serviceName":"CarbonMonoxideSensor","topic":"","manufacturer":"Default Manufacturer","model":"Default Model","serialNo":"Default Serial Number","characteristicProperties":"{}","x":850,"y":580,"wires":[["fea7d8fa.ab258"]]},{"id":"b40fc0e.d2705c","type":"change","z":"54339415.36f384","name":"Set CarbonMonoxideLevel","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload.CarbonMonoxideLevel","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":500,"y":560,"wires":[["c756aa6.24b10d8","72bdfc6c.5a604c"]]},{"id":"edf5ddad.07bb","type":"inject","z":"54339415.36f384","name":"Reset Peak","topic":"","payload":"RESET","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":130,"y":620,"wires":[["c756aa6.24b10d8"]]},{"id":"fea7d8fa.ab258","type":"debug","z":"54339415.36f384","name":"CO Debug","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":1050,"y":580,"wires":[]},{"id":"bfc486e0.5c10f","type":"random","z":"54339415.36f384","name":"Alarm","low":"35","high":"100","inte":"true","property":"payload","x":270,"y":500,"wires":[["b40fc0e.d2705c"]]},{"id":"cbe3274b.6d20c8","type":"random","z":"54339415.36f384","name":"Safe","low":"0","high":"34","inte":"true","property":"payload","x":270,"y":560,"wires":[["b40fc0e.d2705c"]]},{"id":"7411d6ba.d69788","type":"inject","z":"54339415.36f384","name":"","topic":"","payload":"Alarm","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":500,"wires":[["bfc486e0.5c10f"]]},{"id":"97e5b66.bc89448","type":"inject","z":"54339415.36f384","name":"","topic":"","payload":"Non Alarm","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":120,"y":560,"wires":[["cbe3274b.6d20c8"]]},{"id":"d334490b.40dac","type":"homekit-bridge","z":"","bridgeName":"Example Bridge","pinCode":"111-11-111","port":"","allowInsecureRequest":false,"manufacturer":"Default Manufacturer","model":"Default Model","serialNo":"Default Serial Number"}]