Apogee SE-421 Benutzerhandbuch - Seite 17
Blättern Sie online oder laden Sie pdf Benutzerhandbuch für Zubehör Apogee SE-421 herunter. Apogee SE-421 19 Seiten. Ultraviolet-a sensor
TROUBLESHOOTING AND CUSTOMER SUPPORT
Independent Verification of Functionality
If the sensor does not communicate with the datalogger, use an ammeter to check the current draw. It should be
near 1.4 mA when the sensor is not communicating and spike to approximately 1.8 mA when the sensor is
communicating. Any current draw 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/downloads/#datalogger.
Zero Offset Error
With the use of certain dataloggers it is possible to measure a non-zero voltage (zero offset) when the sensor
output should be zero (no UV irradiance incident on diffuser). This offset can be corrected by adding or subtracting
the measured offset from the sensor output. However, if the offset is substantial, and your sensor is outputting
unrealistic values then it may need to be recalibrated. In this case, contact Apogee customer support to recalibrate
the sensor.
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
weatherproof-cable-splice/).
Unit Conversion
SU-200 series UV-A sensors are calibrated in energy flux units of W m
value to photon flux units of µmol m
flux units to photon flux.
1) Calculate the sensor output in units of J m
2) Multiply the energy flux units by the conversion factor. It's important to note that each light source needs
a specific conversion factor. The conversion factor used in the example equation is the sunlight
conversion factor.s
(http://www.apogeeinstruments.com/how-to-make-a-
-2
-1
s
using a conversion factor. Below is an example of how to convert energy
-2
-1
s
.
−2
6 ∗ 10
= 60
60
∗ 0.327
2
-2
. It is possible to convert the energy flux
= 60
2
2
= 19.62
2