Campbell Scientific OBS-3+ and OBS300 Suspended Solids and Turbidity Monitors - Manual (Page 22)

OBS-3+ and OBS300 Suspended Solids and Turbidity Monitors
7.4 Datalogger Programming
CRBasic and Edlog are included in our PC400 and LoggerNet Datalogger
Support Software Packages. CRBasic supports our newer dataloggers (for
example, CR200(X), CR800, CR1000, CR3000). Edlog supports our CR7 and
most of our retired dataloggers (for example, CR510, CR10(X), CR23X).
These program generators use a single-ended voltage instruction ( VoltSE() in
CRBasic or Instruction 1 in Edlog) to measure the high input range and
another single-ended instruction to measure the low input range.
The millivolt measurements are converted to NTU by using the coefficients
provided on the Calibration Certificate. We supply a calibration curve in units
of both millivolts and volts (see Section 7.5, Calibration Certificate).
If using the voltage curve’s coefficients, the multiplier for the singe-ended
voltage instruction needs to be 0.001. If using the millivolt curve’s
coefficients, the multiplier needs to be 1.0.
Make sure you use the correct units.
7.5 Calibration Certificate
The polynomial for converting to NTU is at the top of each curve and is in the
form of:
NTU
S
= A(X) 2 + B(X) + C
Where
A, B, C are provided on the Calibration (see FIGURE 7-2 and FIGURE 7-3).
X = millivolts or volts depending on the curve you are using.
CAUTION
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