Super Systems SDS 8120 - Manual (Page 31)

Super Systems Inc. Page 31 of 104
Color Touch Screen Data Logger Operations Manual
Figure 38 - The About Screen
Calibration
Before using the SDS Data Logger in surveys, it is essential to ensure that the unit is properly
calibrated. This means that raw voltages measured by instruments connected to the data logger
are converted (scaled) to values that accurately reflect the actual voltages. The calibrations that
the user will typically need to perform (before using the data logger in surveys) are the Voltage
Calibration and Cold Junction Trim Calibration (also called CJ Trim). First, the Voltage
Calibration will be performed to ensure that the voltages measured by the leads connected to
each thermocouple are scaled correctly. Second, the CJ Trim will be performed to ensure that
the temperature measured at each data logger terminal (where the cold junction is created) is
correctly scaled. Both types of calibration require a sourcing device and thermocouple wire. The
sourcing device should be calibrated and certified to generate accurate voltages before these
calibrations are performed.
IMPORTANT: Do not perform any of these calibrations without a sourcing device that is properly
connected and sourcing voltage into the proper inputs on the Color SDS Data Logger. Running a
calibration without a sourcing device that is providing voltage into the unit may require
additional calibration steps.
Voltage Calibration
The leads that connect to each input thermocouple measure the voltage generated by that
thermocouple. In most cases, the voltage that the data logger detects (the raw voltage) is
slightly different from the actual voltage generated by the thermocouple. When properly
performed, a Voltage Calibration (also called an Input Calibration) ensures that the SDS Data