SEN0386 datasheet with serial protocol and explanation on negative number encoding format

Hello,
I am looking for the complete datasheet of the SEN0386.
I can't use the library proposed for this sensor and I am ready to write my own library, but for that I would like to have the datasheet of the component with in particular how the negative numbers of each parameter are coded and on how many bits.
A detailed SEN0386 serial protocol notice will help me greatly.
Somebody can help me ?
Thanks