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OMWT-SOFT-OPC Server Corrections
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Corrections
Why Use Corrections
Some devices, like a thermistor, need their data corrected in order to be meaningful.
A thermistor uses resistance to measure temperature. The relation between the
resistance and the temperature is non linear. A thermistor uses a set of correction
parameters to convert resistance to temperature. Other devices may need to correct
data values in a non linear way. OMWT-SOFT-OPC provides a way for the user to
correct the data from a sensor using a set of correction parameters or a lookup table.
Correction IDs
Tell OMWT-SOFT-OPC that you want a device to use a correction by specifying the
Correction ID in the OMWT-SOFT-OPC.INI file. Within the device section add a
line saying "CorrID=" and the number of the correction that you want OMWT-
SOFT-OPC to use. The Corrections are found in the Correction.INI file that you
write.
Pre-defined Thermistor
The thermistor made by the vendor Thermometrics has the part number RL0503-
5820-97-MS . This thermistor's parameters are predefined in OMWT-SOFT-OPC
and given the Correction ID 128. (In the device section of the OMWT-SOFT-
OPC.INI file, write "CorrID=128" to use this type.)
The parameters for the predefined thermistor are as follows:
NTC_DIVIDERES = 10000
NTC_NORMALRES = 10000
Fitting constants:
A = 3.3539264E-3
B = 2.5609446E-4
C = 1.9621987E-6
D = 4.6045930E-8