Need help on passing variable value to device


I am an unsophisticated user. My project consists of a esp8266 D1 mini board connected to an analog soil moisture probe. The program is written in Arduino IDE. The board is powered by a lipo battery charged with a solar cell, and, to save power, I use deepSleep between readings (and turn off power to the probe).

I have built the device, connected to Losant and viewed the data in data explorer. So far, so good.

The deepSleep time is set in code, so if I want to change it, I have to upload new firmware. What I would like to do is set a new value in Losant and send that value to the device, when it is active (ie, not sleeping).

I do not write Json or MQTT and I am confused by how to structure a device command. Is there an example I can follow? If I set a value in Losant, will it be held until read and/or can I call for it when the device is awake? Can it be held constant in Losant during the sleep/wake cycle (during which all variables revert to defined values) or do I need to store the value in EEPROM?

Any help is appreciated.