Hi,
I am receiving water consumption from my Kamstrup Multical 21 meter. The readings are sent each 5 minutes as the current stand in liters:

idx: 258
svalue: "542097"
command: "udevice"

So the next value sent is:

idx: 258
svalue: "542107"
command: "udevice"

Meaning that 10 liters was consumed ...