Writing Volatile Compensation Pressure Value
Request Response
Bytes on the Line
(Hexadecimal)
Description Bytes on the Line
(Hexadecimal)
Description
(silence for 3.5 bytes) Start of Modbus RTU
frame
(silence for 3.5 bytes) Start of Modbus RTU
frame
F0
hex
GMP25x address F0
hex
GMP25x address
10
hex
Function (Write Multiple
Registers)
10
hex
Function (Write Multiple
Registers)
02
hex
Register address 02
hex
Register address
08
hex
08
hex
00
hex
Number of registers to
write (2)
00
hex
Number of 16-bit
registers written (2)
02
hex
02
hex
04
hex
Number of data bytes D4
hex
Modbus RTU checksum
50
hex
Value for the first
register (least significant
word)
93
hex
00
hex
(silence for 3.5 bytes) End of Modbus RTU
frame
44
hex
Value for the second
register (most significant
word)
The response to a write function
informs that the function was
correctly received by the device.
It does not guarantee that the
written value was accepted by
the device (for example, in case
of out-of-range values).
To verify that the value was really
accepted by the device, read the
register value after writing.
7D
hex
0E
hex
Modbus RTU checksum
B7
hex
(silence for 3.5 bytes) End of Modbus RTU
frame
Communication Description
Register address 521 (1-based Modbus documentation format) =
0208
hex
(0-based format used in actual
communication).
Data format Two 16-bit Modbus registers interpreted as IEEE 754
binary32 floating point value, least significant word
first.
Value to write 1013.25 (hPa), in binary32 format 447D5000
hex
.
Appendix A – Modbus Reference
119
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