Vaisala GMW90 - Manual (Page 99)

Appendix B _________________________________________________________ Modbus Reference
VAISALA ________________________________________________________________________ 97
Available measurements depend on the transmitter model. Values may be
unavailable also in case of device failure. Read status registers or
exception status outputs to check for failures. Accessing unavailable
(unsupported or temporarily missing) measurement data does not
generate an exception. “Unavailable” value (a quiet NaN for floating
point data or 0x8000 for integer data) is returned instead. An exception is
generated only for any access outside the GMW90 registers.
A “quiet NaN” value is returned for unavailable values. Writing any NaN
or infinite value is silently ignored.
NOTE A complete 32-bit floating point value should be read and written in a
single Modbus transaction.
Table 44 GMW90 Modbus Status Registers (Read-only)
Name Address Description
Error code (bits 15…0) 0513,6913 0 = no errors
Table 45 GMW90 Modbus Error Code Bits
Bit Description
0 Any critical error is active. Requires transmitter restart or maintenance.
1 Any error is active. May be recoverable.
2 Internal error (Flash)
3 Module communication or compatibility error
4 HTM10 module error
5 Temperature measurement error
6 Humidity measurement error
7 GM10 module error
8 CO
2
measurement error
9 Miscellaneous error
Table 46 GMW90 Modbus Configuration Parameter Registers
Name Metric float Metric
integer
Metric unit &
valid range
Non-metric
float
Non-metric
integer
Non-metric unit &
valid range
Pressure 0777…0779 1029 (×1) 700…1100 hPa 7177…7179 7429 (×1) 700 … 1100 hPa
Elevation 0779…0780 1030 (×1) -700...2300 m 7179…7180 7430 (×1) -2300 … 10000 ft
NOTE Elevation is linked to pressure according to the following equation:
p = 101325 (1 - 2.25577 10
-5 h) 5.25588
where p is pressure in Pa and h is altitude above sea level in m. This
means that changing altitude will also change pressure and vice versa.