Apogee Instruments PYRANOMETER SP-421 Owner's Manual
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Apogee Instruments PYRANOMETER SP-421 Owner's Manual

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OWNER'S MANUAL

PYRANOMETER
Models SP-421
(including SS model)
APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2018 Apogee Instruments, Inc.

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Summary of Contents for Apogee Instruments PYRANOMETER SP-421

  • Page 1: Owner's Manual

    OWNER’S MANUAL PYRANOMETER Models SP-421 (including SS model) APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM Copyright © 2018 Apogee Instruments, Inc.

  • Page 2: Table Of Contents

    TABLE OF CONTENTS Owner’s Manual ..........................................1 Certificate of Compliance ....................................3 Introduction ..........................................4 Sensor Models ......................................... 5 Specifications ........................................... 6 Deployment and Installation ....................................9 Operation and Measurement ................................... 11 Maintenace and Recalibration ..................................17 Troubleshooting and Customer Support..............................18...

  • Page 3: Certificate Of Compliance

    (PBB), polybrominated diphenyls (PBDE). Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products for the presence of these substances, but rely on the information provided to us by our material suppliers.

  • Page 4: Introduction

    Apogee Instruments SP series pyranometers consist of a cast acrylic diffuser (filter), photodiode, and signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor to a measurement device. Sensors are potted solid with no internal air space and are designed for continuous total shortwave radiation measurement on a planar surface in outdoor environments.

  • Page 5: Sensor Models

    SENSOR MODELS This manual covers the SDI-12 protocol model SP-421 pyranometer sensor. Additional models are covered in their respective manuals. Model Signal SP-421 SDI-12 SP-110 Self-powered SP-230* Self-powered SP-212 0-2.5 V SP-214 4-20 mA SP-215 0-5 V SP-420 SP-422 Modbus *Pyranometer model SP-230 is similar to model SP-110, but includes internal heaters designed to keep the diffuser free of precipitation events such as dew or frost.

  • Page 6: Specifications

    Calibration Traceability Apogee Instruments SP series pyranometers are calibrated through side-by-side comparison to the mean of four Apogee model SP-110 transfer standard pyranometers (shortwave radiation reference) under high intensity discharge metal halide lamps. The transfer standard pyranometers are calibrated through side-by-side comparison to the mean of at least two ISO- classified reference pyranometers under sunlight (clear sky conditions) in Logan, Utah.
  • Page 7 Spectral Response Spectral response estimate of Apogee silicon-cell pyranometers. Spectral response was estimated by multiplying the spectral response of the photodiode, diffuser, and adhesive. Spectral response measurements of diffuser and adhesive were made with a spectrometer, and spectral response data for the photodiode were obtained from the manufacturer.
  • Page 8 Cosine Response Directional, or cosine, response is defined as the measurement error at a specific angle of radiation incidence. Error for Apogee silicon- cell pyranometers is approximately ± 2 % and ± 5 % at solar zenith angles of 45° and 75°, respectively.

  • Page 9: Deployment And Installation

    Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure PPFD incident on a horizontal surface, the sensor must be level. An Apogee Instruments model AL-100 Leveling Plate is recommended to level the sensor when used on a flat surface or being mounted to surfaces such as wood. To facilitate mounting on a mast or pipe, the Apogee Instruments model AL-120 Solar Mounting Bracket with Leveling Plate is recommended.
  • Page 10 Cable Connectors Apogee started offering in-line cable connectors on some bare-lead sensors in March 2018 to simplify the process of removing sensors from weather stations for calibration by not requiring the full cable to be uninstalled back to the data logger.

  • Page 11: Operation And Measurement

    OPERATION AND MEASUREMENT The SP-421 pyranometer has a SDI-12 output, where shortwave radiation is returned in digital format. Measurement of SP- 421 pyranometer requires a measurement device with SDI-12 functionality that includes the M or C command. VERY IMPORTANT: Apogee changed all wiring colors of our bare-lead sensors in March 2018 in conjunction with the release of inline cable connectors on some sensors.
  • Page 12 “!” is the last character of a command instruction. In order to be compliant with SDI-12 protocol, all commands must be terminated with a “!”. SDI-12 language supports a variety of commands. Supported commands for the Apogee Instruments SP-421 pyranometers are listed in the following table (“a” is the sensor address. The following ASCII Characters are valid addresses: “0-9”...
  • Page 13 Command Sensor Response Sensor Response when data is ready 0M0! 00011<cr><lf> 0<cr><lf> 0D0! +1000.0<cr><lf> 0M1! 00011<cr><lf> 0<cr><lf> 0D0! +200.0<cr><lf> where 1000.0 is watts/m and 200 is mV. Concurrent Measurement Command: aC! A concurrent measurement is one which occurs while other SDI-12 sensors on the bus are also making measurements. This command is similar to the “aM!”...
  • Page 14 Metadata Commands Identify Measurement Commands The Identify Measurement Commands can be used to view the command response without making a measurement. The command response indicates the time it takes to make the measurement and the number of data values that it returns. It works with the Verification Command (aV!), Measurement Commands (aM!, aM1! …...
  • Page 15 Identify Measurement Parameter Command example: 1IC_001! The Identify Measurement Parameter Command for sensor address 1, C command, data value 1. 1,RW,Watts/meter squared,incoming solar radiation;<CR><LF> The response from sensor address 1, SHEF code RW, units of Watts/meter squared, and additional information of incoming solar radiation.
  • Page 16 Spectral error for Apogee SP series pyranometers as a function of solar zenith angle, assuming calibration at a zenith angle of 45°. Spectral error for Apogee SP series pyranometers as a function of atmospheric air mass, assuming calibration at an air mass of 1.5.

  • Page 17: Maintenace And Recalibration

    MAINTENACE AND RECALIBRATION Moisture or debris on the diffuser is a common cause of low readings. The sensor has a domed diffuser and housing for improved self-cleaning from rainfall, but materials can accumulate on the diffuser (e.g., dust during periods of low rainfall, salt deposits from evaporation of sea spray or sprinkler irrigation water) and partially block the optical path.

  • Page 18: Troubleshooting And Customer Support

    (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/). APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM...

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