Vaisala CARBOCAP GMW80 Series, Руководство пользователя

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A.2.2 16-bit integer format
Table 14 Interpretation of 16-bit signed integer values
Value Description
0000
hex
… 7FFE
hex
Value in range 0 … 32766
8002
hex
… FFFF
hex
Value in range -32766 … -1 (2’s complement)
8000
hex
Value is not available
The 16-bit integer value for measured temperature in Table 15 (page 50) is scaled to include
the necessary decimals.
A.3 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. Subtract 1 from the register number presented
in this manual to get the address used in the Modbus message (for example,
register number 1 corresponds to address 0
hex
in the actual Modbus message).
CAUTION!
Accessing unavailable (temporarily missing) measurement data does not generate a Modbus
exception. “Unavailable” value (a quiet NaN for floating point data or 8000
hex
for integer data)
is returned instead. An exception is generated only for any access outside the applicable
register ranges.
A.3.1 Measurement data registers
Table 15 Modbus measurement data registers (read-only)
Register
number Address Register description Data format Unit
1 0000
hex
Measured CO
2
value 32-bit float ppm
5 0004
hex
Measured temperature
1)
32-bit float °C
257 0100
hex
Measured CO
2
value 16-bit integer ppm
259 0102
hex
Measured temperature (T * 10)
1)
16-bit integer °C
1) Device internal temperature measurement. Measurement accuracy not specified.
GMW80 Series User Guide M211748EN-G
50