Particle variable questions

A couple of basic questions about the cloud Particle variables, that do not seem clear in the docs.

When you call a published variable from the cloud API, does that pull the current known value from the cloud servers, or does it use the Particle cloud to poll the device to request the latest value? How is that affected if the device is in deep sleep mode?

The docs say a limit of 20 variables can be published. Is that per device or per customer?

I’m making a small display to show the latest state of a few of my sensors, but all the values are published to a Thingsboard instance. I’m trying to decide if I should use Particle variables or just pull the data from Thingsboard.

The Particle variable is stored only on the device. If the device is offline, the variable cannot be retrieved. There is no cloud storage of variables. Each variable request queries the device, there is no value cache.

The 20 variable limit is per device. However, since the value can be up to 622 bytes, it’s possible to include multiple pieces of data per variable using comma separated values, JSON, etc…

This might help as well:

https://docs.particle.io/tutorials/device-cloud/introduction/#communication-features

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Thanks.

As my sensors are battery powered and using deep sleep, I’ll pull the values from my graphing server.