Apogee Instruments SP-522 Panduan Pemilik - Halaman 9

Jelajahi secara online atau unduh pdf Panduan Pemilik untuk Aksesori Apogee Instruments SP-522. Apogee Instruments SP-522 19 halaman. Pyranometer

OPERATION AND MEASUREMENT

The SP-522 pyranometer has a Modbus output, where shortwave radiation is returned in digital format.

Measurement of SP-522 pyranometers requires a measurement device with a Modbus interface that supports the

Read Holding Registers (0x03) function.

Wiring

The Green wire should be connected to Ground to enable RS-485 communication, or it should be connected to 12

V power for RS-232 communication. Text for the White and Blue wires above refers to the port that the wires

should be connected to.

Sensor Calibration

All Apogee Modbus thermopile pyranometers (model SP-522) has sensor-specific calibration coefficients

determined during the custom calibration process. Coefficients are programmed into the sensors at the factory.

Modbus Interface

The following is a brief explanation of the Modbus protocol instructions used in Apogee SP-522 pyranometers. For

questions on the implementation of this protocol, please refer to the official serial line implementation of the

Modbus protocol:

http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf

Modbus protocol specification:

Further information can be found at:

Overview

The primary idea of the Modbus interface is that each sensor exists at an address and appears as a table of values.

These values are called Registers. Each value in the table has an associated index, and that index is used to identify

which value in the table is being accessed.

http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf

http://www.modbus.org/specs.php

White: RS-232 RX / RS-485 Positive

Blue: RS-232 TX / RS-485 Negative

Green: Select (Switch between RS-232 and RS-485)

Black: Ground

Red: Power +12 V

(2006) and the general

(2012).