Campbell Scientific CS512 Dissolved Oxygen Probe - Manual (Page 10)

Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
6
8. Calibration
The multiplier is used to calibrate the CS512 probe. To calculate the multiplier:
1) Program the datalogger using a multiplier of one.
2) Place the OxyGuard probe in the air, shaded from the sun. Wait for readings
to stabilize. This may take 15 minutes or more.
3) Determine the air temperature and barometric pressure.
4) Using a calibration chart such as that provided in the probe’s manual,
determine the oxygen concentration of the air.
5) Use the following equation to calculate the multiplier:
M = P/R
M = Multiplier
P = Concentration in PPM of the air (from the calibration chart in Appendix A)
R = The signal output of the OxyGuard probe when using a multiplier of one
6) Change the multiplier in the datalogger program from one to the calculated
number.
A more common way to enter the multiplier is to insert a separate instruction in
the program. This will allow a new multiplier to be added to the program
without rewriting, compiling, and downloading the program to the data logger.
In the CR510, CR10X, and CR23X, use Instruction P36. The multiplier is
entered into an input location called DOmult using the numeric display in
PC200W, PC208W, LoggerNet, PC400, PConnect, PConnectCE, or the
CR10KD.
EXAMPLE 6. Sample Program using P36
57: Z=X*Y (P36)
1: 1
X Loc [ DOmV ]
2: 2 Y Loc [ DOmult ]
3: 3 Z Loc [ DOppm ]
In all dataloggers that use CRBasic, an expression is written. The multiplier
value is entered into the expression through the Public Table using the numeric
display in PC200W, LoggerNet, PC400, PConnect, and PConnectCE.
EXAMPLE 7. Sample Program using Expression
DOppm = DOMult * DOmV