16bit to 1byte

[duvelken]

hi guys,

i need to scale a modbus input which is 16bit to use as a knx scale object to get 0-255 for my lighting control.
the modbus output registers of the device are fixed at 16bit.

what is the best way to scale this ?

thx in advance

[MarkVersluis]

Code:

grp.write('1/1/1', modbusvalue, dt.scale)

or

Code:

value = knxdatatype.decode(modbusvalue, dt.scale)

Something like that?

[admin]

If your modbus device is using full 16-bit range [0..65535], you can use bit shift to discard lowest 8 bits:

Code:

value = bit.rshift(value, 8)
grp.write('1/1/1', value, dt.uint8) -- force value range to [0..255]

Also, I would suggest using profiles instead of scripts.