CS525 ISFET pH Probe
Below is an example program for CR800, CR850, CR1000, and CR3000
dataloggers when the sensor has a ±400 mV output (see Note below).
‘CR1000 Series Datalogger
‘Declare the variable for the pH measurement
Public pHmV
‘Read sensor every 60 seconds
BeginProg
Scan(60,sec,1,0)
‘Code for VoltSE measurements:
VoltSE(pHmV,1, mV250,1,False,0,_60Hz,1,0)
NextScan
EndProg
The mV250 range option may be inadequate for pH ranges that
are greater than 11 or less than 2. At these extreme ranges,
either use Autorange or mV5000.
NOTE
4.2.2 Programming for calibration
In order to output in pH units instead of mV, the offset and multiplier need to
be entered in the datalogger programming. Also, because of the need to
periodically calibrate the pH reading, simple program instructions can be used
to make this process simple. See Appendix A for an example program.
5. Calibration
Calibration should be carried out according to the detailed procedure outlined
in Appendix A.
The calibration should use two or more pH standards (pH4 CSI PN 25587,
pH7 CSI PN 25586, and pH10 CSI PN 25588).
The frequency of calibration will depend on the level of accuracy required and
the coating/fouling nature of the samples being measured.
6. Maintenance
Campbell Scientific recommends that the CS525 be cleaned and calibrated
periodically to insure accurate readings. If the CS525 is not operating properly
and requires return to Campbell Scientific, the customer must get an RMA
(returned material authorization) and fill out the Declaration of Hazardous
Material and Decontamination form. This information can be obtained from
http://www.campbellsci.com/repair.
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