Overview of HMP Series calibration using Modbus protocol - HMP1 - HMP3 - HMP4 - HMP5 - HMP7 - HMP8 - HMP9 - HMPX - MMP8 - TMP1

HMP Series calibration and adjustment using Modbus Technical Note

Document code
M212794EN
Revision
A
Language
English
Product
HMP1
HMP3
HMP4
HMP5
HMP7
HMP8
HMP9
HMPX
MMP8
TMP1
Document type
Technical note

The recommended way to calibrate and adjust HMP Series humidity and temperature probes is using Vaisala's calibration service, Vaisala Insight software, or a compatible handheld meter. However, some users may have a need to implement a solution based on the Modbus protocol. This technical note provides the necessary information to operate the calibration sequence using the Modbus protocol, as well as some additional information about matters affecting the quality of the resulting calibration.

When calibrating and adjusting HMP Series probes using the Modbus protocol, note the following:

  • You can adjust the humidity measurement in 1 … 5 points.
  • You can adjust the temperature measurement in 1 … 2 points.
  • If you are adjusting in more than one humidity point, make sure the first two points are at least 10 %RH apart.

The probe will reject adjustments that are too large, that is, greater than 10 %RH for humidity and 0.5 °C for temperature. If the probe appears to need such a large correction, perform a sensor purge (if available on the probe) and repeat the adjustment procedure. Make sure the measurement has stabilized and the reference environment is reliable. If the required adjustment is still too large, the probe needs to be serviced by Vaisala.

For more information on HMP Series calibration and Modbus implementation, see HMP Series User Guide (M212022EN).