Need Help ? UP or DOWN the shutter 50%

Hi everyone
openhab2 pi 3 update a week ago
alexa
sonoff tasmota

Need Help

SONOFF is connected to dual relay
One to UP, and one to DOWN the shutter
I want to add the option to UP or DOWN the shutter 50%
Everything works fine UP and DOWN, but I can’t set it to 50%

item

//Rollershutter
Switch down "down [%s]" [ "Switchable" ] { channel="mqtt:topic:Mosquitto:Sonoff:ch10", autoupdate="false"}
Switch up "up [%s]" [ "Switchable" ] { channel="mqtt:topic:Mosquitto:Sonoff2:ch11", autoupdate="false"}
Switch half "half [%s]" [ "Switchable" ] { channel="mqtt:topic:Mosquitto:Sonoff3:ch12", autoupdate="false"}
Rollershutter shutter "shutter"  { channel="mqtt:topic:Mosquitto:shutter"}

Thing

Thing topic shutter "shutter" @ "Home" {
    Channels:
     Type switch : ch10 "up" [ stateTopic="stat/windows/POWER1", commandTopic="cmnd/windows/POWER1" ]
     Type switch : ch11 "down" [ stateTopic="stat/windows/POWER2", commandTopic="cmnd/windows/POWER2" ]
     Type switch : ch12 "half" [ stateTopic="stat/windows/POWER2", commandTopic="cmnd/windows/POWER2" ]
     }

sitemap

Frame label="shutter" 
{
Switch item=up icon="blinds"
Switch item=down icon="blinds"
Switch item=half icon="blinds"

rule

 rule "down 13s"
 when
     Item down changed to ON
 then
         down.sendCommand(ON)
         createTimer(now.plusSeconds(13),  [ |
         down.sendCommand(OFF)
     ])
 end

rule "up 13s"
 when
     Item up changed to ON
 then
         up.sendCommand(ON)
         createTimer(now.plusSeconds(13),  [ |
         up.sendCommand(OFF)
     ])
 end

Thank you

Does the sonoff know the percentage as it’s moving the shutter?

Have a look at this topic for sonoff dual relay:

No, i have seen in paperUI is set to 1 to up and 0 to down

Thank you