User Manual

TROUBLESHOOTING AND CUSTOMER SUPPORT
Independent Verification of Functionality
If the sensor does not communicate with the datalogger, use an ammeter to check the current drain. It should be
near 0.6 mA when the sensor is not communicating and spike to approximately 1.3 mA when the sensor is
communicating. Any current drain greater than approximately 6 mA indicates a problem with power supply to the
sensors, wiring of the sensor, or sensor electronics.
Compatible Measurement Devices (Dataloggers/Controllers/Meters)
Any datalogger or meter with SDI-12 functionality that includes the M or C command.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee webpage at
https://www.apogeeinstruments.com/datalogger/#downloads.
Modifying Cable Length
SDI-12 protocol limits cable length to 60 meters. For multiple sensors connected to the same data line, the
maximum is 600 meters of total cable (e.g., ten sensors with 60 meters of cable per sensor). See Apogee webpage
for details on how to extend sensor cable length (http://www.apogeeinstruments.com/how-to-make-a-
weatherproof-cable-splice/).
Unit Conversion Charts
Apogee SQ series quantum sensors are calibrated to measure PPFD in units of µmol m
-2
s
-1
. Units other than
photon flux density (e.g., energy flux density, illuminance) may be required for certain applications. It is possible to
convert the PPFD value from a quantum sensor to other units, but it requires spectral output of the radiation
source of interest. Conversion factors for common radiation sources can be found in the Unit Conversions page of
the Support Center on the Apogee website (http://www.apogeeinstruments.com/unit-conversions/). A
spreadsheet to convert PPFD to energy flux density or illuminance is also provided in the in the Unit Conversions
page of the Support Center on the Apogee website (http://www.apogeeinstruments.com/content/PPFD-to-
Illuminance-Calculator.xls).