Campbell Scientific CS320 Users Guide

Overview

The CS320 is a digital thermopile pyranometer that measures
broad-spectrum short-wave radiation and communicates over
the simple SDI-12 protocol to the data logger. This sensor
design eliminates measurement error and programming errors
that can adversely affect data quality.

This pyranometer has been designed to improve the global
solar radiation measurement significantly (even under cloudy
conditions) without adding substantial cost. The CS320 is
suitable for applications ranging from environmental research

Thermopile sensor eliminates spectral errors associated with
silicon-cell pyranometers

Much lower price point than other thermopile sensors
On-board sensor automatically detects if the CS320 is level

for installation, diagnostics, and remote troubleshooting
Designed for long-term stability and deployment
Dome-shape sensor head allows dew and rain runoff

The CS320 combines a blackbody thermopile detector with
anacrylic diffuser. This design is a significant improvement
when compared withthe spectral response of silicon photocell
pyranometers, while offeringa comparable price. Thermopile

Digital Thermopile Pyranometer

CS320

PRODUCT

Thermopile
Accuracy,
Digital
Simplicity,
Affordable
Price

For measurement of global solar
radiation under changing
weather conditions

to agriculture to large mesoscale weather networks
(mesonets).

The CS320 is manufactured using a high-grade anodized
aluminum body and IP68-rated 316 stainless-steel M8
connector (marine grade). The CS320 sensor is heated (on/off
switchable under user control) and allows continuous
operation in changing environmental conditions. The
pyranometer's calibration data is stored on the sensor.

Benefits and Features

Detailed Description

Internal heater to reduce errors from dew, frost, rain, and
snow

SDI-12 digital output
Detachable waterproof connector from sensor head for fast,

easy servicing
Calibration data stored on sensor

pyranometers use a series of thermoelectric junctions (multiple
junctions of two dissimilar metals following the thermocouple

principle) to provide a signal of several µV/W/m2 proportional
to the temperature difference between a black absorbing

For comprehensive details, visit: www.campbellsci.com/cs320

surface and a reference. The thermopile pyranometer’s black
surface uniformly absorbs solar radiation across the solar
spectrum.

The 0.2 W heater keeps water (liquid and frozen) off the sensor
to minimize errors caused by dew, frost, rain, and snow
blocking the radiation path. Dew and rain runoff is faciliated by
the dome-shaped sensor head (diffuser and body). This keeps
the sensor clean and minimizes errors caused by dust blocking

Sensor Thermopile detector, acrylic

diffuser, heater, and signal
processing circuitry mounted in an
aluminum housing

Measurement Description Measures broad-spectrum short-

wave radiation
ISO Classification Class C (second class)
Calibration Uncertainty ± 2.6%
Measurement Range

0 to 2000 W/m2 (net short-wave

irradiance)
Measurement Repeatability < 1%
Long-Term Drift < 2% (per year)
Non-Linearity < 1%
Sensitivity

0.057 mV/W/m

2

Detector Type Blackbody thermopile
SDI-12 Response Time 2 s
Field of View (FOV) 180°
Spectral Range 385 to 2105 nm (50% points)
Directional (Cosine)

Response

< ±20 W/m2 (at 80° solar zenith)

Temperature Response < 5% (from -15° to +45°C)
Output SDI-12 (version 1.4) 1200 bps
Zero Offset A

8 W/m

2

Zero Offset B

< 5 W/m

2

Specifications

the radiation path. The sensor ishoused in a rugged anodize
aluminum body, and the electronics are fully potted.

The CS320 pyranometer has sensor-specific calibration
coefficients determined during the custom calibration process.
Coefficients are programmed into the microcontrollers at the
factory. The CS320 has an SDI-12 output (SDI-12 version 1.4),

where short-wave radiation (W/m2) is returned in digital
format. Measurement of the CS320 pyranometer requires a
measurement device with SDI-12 functionality that includes
the M or C command.

Operating Temperature

-50° to +50°C

Range
Operating Environment 0 to 100% relative humidity
Heater 0.2 W (on-board)
Heater Power Requirements25 mA current drain (at 12 Vdc)
Input Voltage Requirements6 to 24 Vdc
Current Drain 3 mA (standby)

5 mA (measurement)

Uncertainty in Daily Total < 5%
Error Due to Clouds ±2 %
Mechanical Rating IP66/68
Factory Calibrations Traceable to secondary standard

blackbody thermopile
pyranometers traceable to the
world radiation reference in Davos,
Switzerland.

Compliance with Standards 2011/65/EU RoHS Directive

2015/863/EU RoHS Phthalates
Amendment

Warranty 4 years against defects in materials

and workmanship
Diameter 3.43 cm (1.35 in.)
Height 3.96 cm (1.56 in.)
Weight ~65 g (2.3oz)

May vary due to potting.

For comprehensive details, visit: www.campbellsci.com/cs320

© 2021 Campbell Scientific, Inc. | 03/26/2021