Apogee SI-411 Instrukcja obsługi - Strona 19

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Apogee SI-411 Instrukcja obsługi

TROUBLESHOOTING AND CUSTOMER SUPPORT

Independent Verification of Functionality
The simplest way to check sensor functionality is the aM2! command. This command returns detector temperature
and detector voltage output. Detector temperature should read very near room temperature. When the aperature
of the sensor is covered with aluminum foil, the voltage output should read very near 0 mV.
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
http://www.apogeeinstruments.com/content/Infrared-Radiometer-Digital.CR1.
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/).
Signal Interference
In instances where SI-400 series radiometers are being used in close proximity to communications (near an
antenna or antenna wiring), it may be necessary to alternate the data recording and data transmitting functions
(i.e., measurements should not be made when data are being transmitted wirelessly). If EMI is suspected, place a
tinfoil cap over the front of the sensor and monitor the signal voltage from the detector. The signal voltage should
remain stable at (or very near) zero.