Modbus Binding - How to read and show State?

I’m working for Dupline Binding. Communication seems to work, but how to read the 0/1 bit in response?

My Config:

############################### Modbus Binding
// sets refresh interval to Modbus polling service.
// Value in milliseconds (optional, defaults to 200)
modbus:poll=1000
modbus:serial.slave1.connection=/dev/ttyUSB0:9600:8:none:1:rtu
modbus:serial.slave1.id=1
modbus:serial.slave1.start=1536
modbus:serial.slave1.length=1
// The data type, can be “coil” “discrete” “holding” “input”
modbus:serial.slave1.type=discrete
// Can be “bit”, “int8”, “uint8”, “int16”, “uint16”, “int32”, “uint32”, “float32”
modbus:serial.slave1.valuetype=bit

My Items:
//Gruppen
Group Test

/*Funktionen */
//Switch Du1 (Test) {modbus=“slave2:0”, autoupdate=“false”}

Contact Du1 “A1 [MAP(en.map):%s]” (Test) {modbus=“slave1:0”}
Switch Du2 “A2” (Test) {modbus=“slave1:1”}
Switch Du3 “A3” (Test) {modbus=“slave1:1”,autoupdate=“false”}

Switch Du4 “B1” (Test) {autoupdate=“false”}
Switch Du5 “B2” (Test) {autoupdate=“false”}
Switch Du6 “B3” (Test) {autoupdate=“false”}

Not complete, only for testing…

LOG-Info:

The communication work. Change on Dupline are read correct.
How can i Display the 0 or 1 state?
Switch/State in the UI always OFF/0

Thanks for help/idea…