Stream: implementers
Topic: Value of a setting as DeviceMetric
Grigoreta Cojocar (Jul 18 2018 at 11:14):
Hello,
We have to model some devices that have a characteristic called "focal length". Should we use a DeviceMetric resource for the characteristic, or should we use a DeviceComponent. If we use a DeviceMetric with category=setting, where should we keep the value of the characteristic?
Lloyd McKenzie (Jul 18 2018 at 14:52):
@Eric Haas ?
Eric Haas (Jul 18 2018 at 16:01):
Device metric decsribe the setting capability not sure if an how it handles the settings actual value. @Brian Reinhold ?
Stefan Karl (Jul 18 2018 at 17:59):
You need an observation to convey the value. Observation.device refers to the DeviceMetric, and DeviceMetric.category indicates that this is a setting.
Lloyd McKenzie (Jul 18 2018 at 18:29):
Device and DeviceComponent are being merged. So you should soon have the ability to specify Device.property directly. There are actually two different types of device properties. There are some that are innate to the device that are determined during manufacturing/production and are unchangeable. (You can't take a 5cc syringe and convert it to a 10cc syringe.) There are other properties that are changeable and time-bound - for example the seat height of an adjustable wheelchair, the configuration parameters of a pacemaker, etc. I believe the intention is that Device.property is going to be used for the former and Observation for the latter?
Stefan Karl (Jul 18 2018 at 18:34):
Yes, that's my understanding. Device(Component).property is used for static properties, mainly for PHD devices.
Lloyd McKenzie (Jul 18 2018 at 18:43):
So if the focal length is a fixed property, use Device(Component).property. If it's a configuration setting, use Observation.
Eric Haas (Jul 18 2018 at 19:54):
Why can't DeviceMetric have variables? It seems like DeviceMetric would a natural place to define device settings using a name value pair - sounds more logical to me instead of overloading Observation even more.? Just asking...
Brian Reinhold (Jul 18 2018 at 20:49):
Device metric decsribe the setting capability not sure if an how it handles the settings actual value. @Brian Reinhold ?
@Eric Haas Not really my specialty. DeviceMetric is not used by PHD. To be honest I am not sure how the DeviceMetric fits in given the Observation (I am not sure what it represents). I have an inkling it describes the measurement capabilities of the device or things about the measurements it has. In PHD settings are reported as Observations. For example, in a BCA the height may be a setting in the sense it is input as a parameter for the device and not actually measured by the device. Other observations from such devices where measurements are based upon the setting are typically referenced by source handle references.
I have a feeling this does not help much!
Eric Haas (Jul 18 2018 at 21:27):
thanks Brian, I thought you were the expert!
Brian Reinhold (Jul 18 2018 at 21:29):
thanks Brian, I thought you were the expert!
Eric, You might want to ask @John Rhoads or @Stefan Karl. They are PoCD guys and use the DeviceMetric
Last updated: Apr 12 2022 at 19:14 UTC
