Water Level Sensor Capability

Developer Programs Writing Device Types
1

Hi Guys

Any idea what the best capability would be to report a level from a sensor? Specifically a water level in a tank? I want to report as a percentage to full but cant see any sensor level capabilities. All I can see is Switch Level which seems to be for devices controlling the level of something (dimmer, volume, speed etc).

Any ideas?

Nick

2

i donā€™t think iā€™ve seen any z-wave or zigbee sensor with this capability

3

SmartThings is slow to add new Capabilities, and they ā€œneverā€ consult the Community for ideas or feedback on them. Reference the Category:

https://community.smartthings.com/c/developers/new-capability-types

Soā€¦

You have 2 choices.

  1. Just use Capability ā€œSensorā€ and add arbitrary Attribute(s)

  2. Or use any Capability that has a numeric value for a sensor (e.g., Temperature, Switch Level, Power, ā€¦).

I strongly recommend approach #2, because then your DTH will be instantly compatible with SmartApps that react to that Capability as an input.

e.g., If there is a SmartApp that ā€œalert me when it is too hotā€, then writing your Water Level to Temperature will immediately be able to use that SmartApp!

(And apps like ActionTiles will be able to display your Water Level on a Temperature Tile).

1 Like
4

Hi Jimmy

I am making my own LAN connected device to report the value, but just need the best way to record it in ST. I can quite happily use an attribute and custom commands to handle the data but thought there might be a more ā€˜standardā€™ way.

Nick

1 Like
5

Itā€™s not so much that there is a ā€œstandardā€, as there is a lack of standards.

  • The only way you can be certain your DTH will work with existing SmartApps is if you use one of the existing Capabilities.

  • It is also acceptable to do it both at the same time. e.g., create an ad hoc Attribute ā€œwaterLevelā€ while also writing the same value to Attribute ā€œtemperatureā€ (and claiming Capability ā€œtemperature measurementā€). For devices that donā€™t emit a lot of events, the overhead is trivial.

1 Like
6

Just curious, if he chose Switch Level, which is read write, can he override it and make it read only? Or would his Setter just throw a silent exception?

1 Like
7

Technically, SmartThingsā€™s ā€œDevice Instance Objectsā€ donā€™t have setter methods; instead, they offer Commands which may have the side effect of changing the values of Attributes.

If a DTH claims Capability ā€œSwitch Levelā€, then it should / must offer the setLevel() Command.

Thereā€™s no contract that the Command must perform any function successfully. I think it would be safest to fail silently, or post a warning to Live Logging; but a more severe Error is likely unnecessary.

If you donā€™t provide at least a stub Command, then you risk App and SmartApp exceptions with possibly serious implications, such as crashing (since such apps may not have been written with clean exception trapping).