As the Fibaro HCL does not support LUA. The question was how to update the number value of the slider to send to the HTTP string. Thanks to this site which is a really good reference https://www.vesternet.com/resources/application-notes/apnt-88/
The 2 use cases here are;
- Sonos HTTP API Volume
To allow for volume control for all Sonos devices, add a virtual device with the IP address for SONOS HTTP API and specify the default port to 5005. Create Slider and put the following text into the string.
GET /volume/_sliderValue_ HTTP/1.10x0D0x0A0x0D0x0A
- Domotiz Virtual Devices
GET /json.htm?type=command¶m=switchlight&idx=XX&switchcmd=Set%20Level&level=_sliderValue_ HTTP/1.10x0D0x0A0x0D0x0A
Replace XX with the device ID.