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SQ-421X-SS SDI-12 Digital Output Quantum Sensor

Updated:2025-03-13

Brand: Apogee
Model: SQ-421X-SS
Description: The SQ-421X-SS is a digital sensor that uses SDI-12 communication protocol. The sensor is calibrated for sunlight and has a command that automatically applies the immersion effect correction factor fo
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Product Details

Overview of SQ-421X-SS SDI-12 Digital Output Quantum Sensor：

User's Manual

The SQ-421X-SS is a digital sensor that uses SDI-12 communication protocol. The sensor is calibrated for sunlight and has a command that automatically applies the immersion effect correction factor for underwater measurements. The sensor features a rugged, self-cleaning sensor housing design, and high-quality cable terminating in pre-tinned pigtail leads for easy connection to dataloggers and controllers. Typical applications include PPFD (Photosynthetic Photon Flux Density) measurement over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PAR (Photosynthetically Active Radiation)/PPFD in aquatic environments, including salt water aquariums where corals are grown.

SQ-421X-SS Sensor Drawing：

Specifications of SQ-421X-SS:

Input Voltage Requirement	5.5 to 24 V DC
Current Draw	1.4 mA (quiescent), 1.8 mA (active)
Calibration Uncertainty	± 5 %
Measurement Repeatability	Less than 1 %
Long-term Drift (Non-stability)	Less than 2 % per year
Non-linearity	Less than 1 % (up to 2500 μmol mˉ2 sˉ 1)
Response Time	0.6 s, time for detector signal to reach 95 % following a step chang, fastest data tranmission rate for SDI-12 circuitry is 1 s
Field of View	180?
Spectral Range	370 to 650 nm ( wavelengths where response is greater than 50 % fo maximum)
Directional (Cosine) Response	± 5 % at 75? zenith angle
Temperature Response	Less than 0.5 % from -20 to 50 C
Operating Environment	-20 to 60 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions	30.5 mm diameter, 37 mm height
Mass (with 5 m of cable)	140 g
Cable	5 m of two conductor, shielded, twisted-pair wire, additional cable available in multiples of 5 m; TPR jacket (high water resistance, high UV stability, flexibility in cold conditions); pigtail lead wires
Warranty	4 years against defects in materials and workmanship
Manufactured	Made in the USA