OPTO 22 PAMUX, User Manual

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Pamux User’s Guide
C-1
TEMPERATURE
CONVERSION ROUTINES
TEMPERATURE
CONVERSION ROUTINES
OVERVIEW
Readings from analog input modules are returned as raw counts, nominally in the range of 0–4095.
To convert this data to temperatures in degrees C, the algorithms in this appendix must be used. To
accommodate the non-linearity of the temperature devices, some of these algorithms require various
coefficients.
Throughout these algorithms, VALUE% is a decimal number representing the value read from the
module. Value is:
• less than 0 when the module is below zero scale;
• equal to 0 when the module is at zero scale;
• equal to 4095 when the module is at full scale;
• greater than 4095 when the module is above full scale.
The data returned from a direct reading of an analog input will include an offset of 4096 to
accommodate over- and under-range indications. If you are using the Pamux driver, this offset is
subtracted automatically. If you are not using the driver, you must first subtract 4096 before using the
reading in an algorithm.
For example, if a B6 reads the data from an analog input as 4110, VALUE% is 4110 - 4096 = 14,
indicating the input is slightly above zero scale. If the B6 reads the data as 4082, VALUE% is 4082 -
4096 = -12, indicating the input is slightly below zero scale.