Configuration of modbus

DEAR Sir,

I have configure my FSCA-01 modbus card of VFD ABB 850 with ABB800xA DCS modbus sucessfully. I am in trouble that DCS read only 16 Bit length real value and not read 32 Bit length real value. when i give (MW10#16) give real value of 16 bit but when give 32 bit error show "Illegal value data" . What could i do in programming ?