SOMFY RS485 RTS Handbuch Seite 52

RS485 communication standard
All signals on the physical link between devices should comply with EIA/TIA-485-A
standard.
Recommended cable : Shielded , two twisted- pair type 22 - 24 AWG (120 Ω)
Communication mode : half-duplex
Between two messages, leave 100 ms approx.
Each character is coded as follow :
Baud Rate
Start bit
Data bits
Parity
Stop bit
50
Character coding
4800
Logical Level 0
8
Odd
Logical Level 1
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+/-2%
Less significant bit transmitted first