User's Manual

File : CS-SUP-MUTI-WTHERMSPETEC-E02.sxw
2.2.2 CALIBRATION OF RADIO MODULE
➢ Factory calibration
The precision of PT100 and PT1000 probes is such that the WaveTherm module measurement chain
requires calibration.
This calibration is carried out automatically in the factory and the product is supplied ready for use.
➢ Re-calibration on site
Re-calibration on site is possible under certain conditions.
To carry out this operation, it will be necessary to connect two calibration precision resistances.
Remark: Calibration is therefore only possible on WaveTherm PT100 (or PT1000) modules equipped with
two probe inputs.
The WaveTherm PT100 and PT1000 modules possess two module calibration parameters. These
parameters are accessible in read-only and are updated with a calibration command
They contain the internal reference resistance values used during temperature measurement.
 Parameter 0x30 : value of the internal reference resistance very low
 Parameter 0x31 : value of the internal reference resistance very high
Calibration is therefore carried out using precision calibration resistances for accurate measurement of the
internal reference resistances and storage of the associated results in internal parameters. These values are
then used during temperature measurement.
Remark : Calibration resistance value:
- for WaveTherm – PT100 : 60 and 160 ohms.
- for WaveTherm – PT1000 : 160 and 1600 ohms.
2.2.3 SETTING OF PROBE COEFFICIENT PARAMETERS
The PT100 and PT1000 probes have a coefficient providing a linear temperature response.
Remark : The European standard EN60751 relative to probes defines 3 coefficients A,B and C used in
the calculation of the relationship : resistance = f (temperature).
 In the -200 to 0°C range : R = R0[1+At + Bt
2
+ C(t – 100°C)t
3
)
 in the -0°C to 850°C range: R = R0(1+At + Bt
2
)
R0 : Resistance at 0°C
A, B and C: transfer coefficients
As the WaveTherm module operating mode consists of measuring the probe resistance and then calculating
the temperature, it requires coefficients in order to calculate the relationship between these values:
temperature = f (resistance)
and not resistance = f (temperature).
WaveTherm module technical specifications page 15 of 31