I think it is a combination of the device exposing the flash capability and the specific driver supporting flash.
As far as I know, there is no flash capability and that action lists all my devices with the switch capability so I'm assuming Rule Machine is using a custom command that they've included in some of their built-in switch drivers.
Since it's not officially part of a capability it probably won't work with most devices...
I know Hue bulbs have a flash capability. I have used custom Zwave drivers that had enabled flash on my GE dimmers. Dimmers normally fade on and off rather than an instant on/off. Flash worked well on those dimmers.
There isn't a flash capability because if there was then only the devices that support flash would be listed in Rule Machine when you select that action, but it's displaying all my Switches instead so that's the capability it must be using the "switch" capability to generate the device list for the flash action.
If they added the command "flash" to the Switch capability then it would work with all the devices that get listed for the flash action, but it doesn't which is why it must be a custom command that's supported by Rule Machine, Hubitat Safety Monitor, and some of the custom drivers, like the Hue bulbs.
Hubitat has the capabilities "Light" and "Bulb" so they should really add the "flash" command to one of those...
I had a similar discussion with Bruce about devices showing up that couldn't do something. His words were to the effect that RM wasn't able or capable of a query.
Here is a discussion about flashing lights and about a device not supporting the flash command. There is also mention of a device with the flash capability. Read the parts about dim ramp. Hue bulbs do support the flash command but I don't know whether HE can or does send the flash command to the Hue bridge.
No, it's officially part of the HSM routines. I have not added anything to it, wouldn't know how to. I'm using Hubitat right out of the box.
Flashing is one option for available lights. The other is just to turn on/off.
I just tried the 3 types of bulbs I have with the flash command in a test rule. None of them would flash. They are ERIA CT and color, Sengled CT and color, and Yeelight CT. Just FYI.
Like I said, there is no flash capability.
Some drivers have a custom command called flash which Hubitat is using with the switch capability.
Because there is no flash capability, there's no easy way for an app to just list the devices that support the flash custom command so the built-in Hubitat apps are using the Switch capability instead.
It's basically trial and error to figure out which drivers support it and which don't.
Just because a device's hardware has the ability to flash doesn't mean that it was implemented in the driver. The opposite is also true because a driver could implement it using a series of on/off commands with delays for devices with hardware that doesn't support flashing.
It would be really nice if Hubitat added a "Flash" capability so that the flash actions in the built-in apps would only list devices with drivers that support it.
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You will believe what you are going to believe. If a device doesn't support a flash command you would need to do an on and off less than a second apart. Most devices are incapable of responding to an on/off command that quickly. The ability to flash is at the device level where a single command is issued to flash. The device itself does the flashing.
That doesn't mean that there is a device capability called "flash". This is the list of supported device capabilities with Hubitat. I think the confusion is that you are using the word "capability" to mean "a command the device is able to perform" and the term "capability" in this context, means a very specific thing.
How about the device supports a command to flash, which the device understands and is able to perform.
Have a look at @bravenel's response in my post just above yours.
My point is that there is no Device Capability of flash. (and I am using the capital letters on purpose) @krlaframboise is correct. You are using a home automation technical term with it's common, English definition and that is what is causing the confusion. I provided a link to the device capabilities that Hubitat supports. Do you see anything called Flash listed? No, cause it isn't there.
Look at your device drivers. There is a listing of the capabilities the device uses and the commands the device has. Flash will be listed as a command, not a capability.
Talking outside of HE, Hue bulbs support flash. You can issue a flash command to the bulbs through a curl command line and the bulbs will flash. How is that not a Device Capability? Curl certainly does not have the ability to flash the lights.
Because Device Capability is a specific term that has a specific use to mean a common capability supported by the platform. A device capability has a list of contained commands that do not have to be called out specifically in the listing of the custom commands for that device because it is understood that if a device has that capability it will support that list of commands. For example, the Switch capability supports the on() and off() commands. You don't have to list them under the list of commands because they are packaged in the switch capability.
I have said it twice now. You are using capability with it's common, English definition. But in the world of Hubitat, the word Capability has a much more specific and technical usage. Not that either one of them is wrong...but one is more right because of the context. And I point this out as to remove confusion because when you ask about the flash capability it will cause confusion because flash is not on the list of supported capabilities for hubitat, which I linked to above.
And yet Bruce says "Our built-in drivers for dimmers and bulbs include flash command. Not all devices support flash".
This isn't worth this much effort and we will need to agree to disagree.
He said COMMAND. NOT CAPABILITY. Why are you using those two words interchangeably? Are you even reading my responses?
@bravenel, can we get an official ruling? Is Flash a supported capability in Hubitat?
Everything @Ryan780 said is correct...
When you choose the flash action in the built-in Hubitat apps it lists all the devices with the "Switch" capability because there is no such thing as a "Flash" capability in Hubitat.
Almost all of the drivers for Sirens, Water Valves, Window Shades, etc. support the Switch capability because they all have "on/off" functionality which is why they're included in the device list for the flash action, but they obviously don't have a flash custom command so nothing will happen if you select them.
If the devices in that list are using a driver with a custom flash command they'll work with the flash action, otherwise they won't. Whether or not the device hardware has the ability to flash is irrelevant in this situation.
Almost all of the generic Z-Wave switch/dimmer drivers have a custom "flash" command which simulates flashing by turning the device on and off with delays. It works with several devices that don't have any type of built-in flash functionality, although since it's a simulated effect it's not that reliable.
I somehow missed this post, but Bruce went on to say "In some cases the driver does it." and "If the driver supports flash command, it will be on the device details page" which sums up what we've been saying.
In the Hubitat and SmartThings world, the device handler/driver determines the device's functionality, not the device itself. Just because a device's hardware supports a feature doesn't mean the driver exposes it and drivers sometimes simulate functionality that the device's hardware doesn't support, like the custom flash command in some of the built-in switch drivers.
