Modbus TCP/IP: read_swap not work

[Domoticatorino]

Hi,
here enclosed register map of a device. What is wrong with json profile below?

{"name":"Heating Energy kWh","bus_datatype":"int32","datatype":"int32","type":"register","address":71,"read_swap":"w"}

I mean the I read the same value declaring "read_swap":"w" or not declaring it. 

Where is my fault please?

Thanks.

BR