The Universal RTS interface has very limited set of commands, which is why it can afford simpler protocol.
"A single RS485RTS transmitter manages 16 groups of up to 10 motorised shading devices each. Supported functions include: open, close, stop, go/record/delete a preset position, sun protection and tilting (specially suitable for venetian blinds)." In addition, the RS485 transmitter can query and receive the shade's status.
I was looking into possibility to replace my URTS with this transmitter to expand control functionality, but only found it sold in UK and for a very high price...