Vaisala HMP Series, User Manual

Page: 103 / 118

A.4 Modbus registers
Registers are numbered in decimal, starting from 1. Register addresses in actual Modbus
messages (Modbus Protocol Data Unit (PDU)) are in hexadecimal and start from zero. Register
number 1 corresponds to address 0
hex
in the actual Modbus message.
Reading the wrong register(s) may result in correct-looking values.
Check the reference documentation of your Modbus host (PLC) to verify which
notation it uses for Modbus register addresses.
CAUTION!
A.4.1 Measurement data registers
Table 75 Floating point measurement data registers (read-only)
Register
number Address Register description Data format Unit
1 0000
hex
Relative humidity 32-bit float %RH
0001
hex
3 0002
hex
Temperature 32-bit float °C
0003
hex
7 0006
hex
Dew point temperature 32-bit float °C
0007
hex
9 0008
hex
Dew/frost point temperature 32-bit float °C
0009
hex
11 000A
hex
Dew/frost point temperature
at 1 atm 32-bit float °C
000B
hex
13 000C
hex
Dew point temperature at 1
atm 32-bit float °C
000D
hex
15 000E
hex
Absolute humidity 32-bit float
g/m
3
000F
hex
17 0010
hex
Mixing ratio 32-bit float g/kg
0011
hex
19 0012
hex
Wet-bulb temperature 32-bit float °C
0013
hex
Appendix A – Modbus reference
101