Appendix H - Float Definition - Siemens SITRANS F M MAGFLO series Operating Manual

Modbus RTU RS-485
APPENDIX H
Float Definition
APPENDIX H
Stuffing of multi-byte numbers into multiple Modbus RTU registers differs among Modbus
devises.
„Big Endian" and „Little Endian" describe the order or sequence in which multi-byte data is stored
in memory. This device uses (as IEEE and Honeywell) a 'Big-Endian' representation for
addresses and data items. This means that when a numerical quantity larger than a single byte
is transmitted, the MOST significant byte is sent first.
Value IEEE FP B
(decimal) MSB LSB
100.0 42C80000h
55.32 425D47AEh
2.0 40000000h
1.0 3F800000h
-1.0 BF800000h
Read absolute massflow (4:03001)
Query: 01,03,0B,B8,00,02,46,0A
Response: 01,03,04,40,C3,52,93,62,C8
Absolute massflow = 6.10383 kg/s
SFIDK.PS.023.D2.02
Register N
high low
42h C8h
42h 5Dh
40h 00h
3Fh 80h
bFh 80h
Register N + 1
high low
00h 00h
47h AEh
00h 00h
00h 00h
00h 00h
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