Met One Instruments BX-597A User manual

MODEL BX-597A
Temperature / Relative Humidity /
Barometric Pressure Sensor
Operation Manual
Document No. BX-597A-9800 Rev C
Met One Instruments, Inc
1600 NW Washington Blvd.
Grants Pass, Oregon 97526
Tel: [phone]
Fax: [phone]

BX-597A-9800 Manual Rev C
Copyright Notice
Model BX-597A Relative Humidity / Temperature / Barometric Pressure Sensor Manual.
© Copyright 2020 Met One Instruments, Inc. All Rights Reserved Worldwide. No part of this
publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or
translated into any other language in any form by any means without the express written
permission of Met One Instruments, Inc.
Technical Support
Should you require support, please consult your printed documentation to resolve your
problem. If you are still experiencing difficulty, you may contact a Technical Service
representative during normal business hours—7:30 a.m. to 4:00 p.m. Pacific Standard Time,
Monday through Friday.
Voice: [phone]
Fax: [phone]
E-Mail: [email protected]
Mail: Technical Services Department
Met One Instruments, Inc.
1600 NW Washington Boulevard
Grants Pass, OR 97526

Safety Notice
The contents of this manual have been checked against the hardware and software described
herein. Since deviations cannot be prevented entirely, we cannot guarantee full agreement.
However, the data in this manual is reviewed regularly and any necessary corrections included
in subsequent editions.
Faultless and safe operation of the product presupposes proper transportation, storage, and
installation as well as careful operation and maintenance. The seller of this equipment cannot
foresee all possible modes of operation in which the user may attempt to utilize this
instrumentation. The user assumes all liability associated with the use of this instrumentation.
The seller further disclaims any responsibility for consequential damages.

BX-597A-9800 Manual Rev C
Table of Contents
1. Introduction........................................................................................................... 1
2. Cautionary Statements ......................................................................................... 1
3. Initial Inspection.................................................................................................... 1
4. Product Overview.................................................................................................. 2
5. Installation............................................................................................................. 3
5.1. Mounting................................................................................................................ 3
5.2. Siting...................................................................................................................... 3
5.3. Wiring..................................................................................................................... 3
6. Specifications........................................................................................................ 4
7. Sensor Verification ............................................................................................... 5
8. Serial Communications ........................................................................................ 5
9. Maintenance .......................................................................................................... 7
10. Service ................................................................................................................... 7
11. Wiring Diagrams.................................................................................................... 8
12. Terminal Mode Commands ................................................................................ 10

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1. Introduction
The Model BX-597A multi-parameter weather sensor is an “All-in-One” device that
measures ambient temperature, relative humidity, and barometric pressure. Sensor
performance complies with guidelines establish by the World Meteorological Organization
(WMO) and the US Environmental Protection Agency (EPA). The sensor is supplied with
mounting hardware and an integrated radiation shield and can be easily attached to lattice
tower legs and instruments masts up to 2 inches (IPS) in diameter.
2. Cautionary Statements
The sensor’s relative humidity output is referenced to saturated water vapor pressure
above liquid water. When the air temperature is below freezing, the sensor’s maximum
theoretical measurement range is limited.
To minimize exposure to direct sunlight, install the sensor facing to the north in the
northern hemisphere and south in the southern hemisphere. This orientation will help
shield the sensor from direct sunlight and reduce temperature measurement errors.
3. Initial Inspection
Upon receipt of the Model BX-597A, inspect the packaging and contents for damage. If
the packaging has arrived in a damaged condition file a claim with the shipping
company and contact Met One Instruments, Inc. to arrange for repair or replacement.
The model number and cable length are printed on a label at the connection end of the
cable. Check this information against the shipping documents to ensure the correct
product and cable length has been received.

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4. Product Overview
The BX-597A ships from Met One Instruments pre-wired for digital output signals including RS-
232 and RS-485. The BX-597A also includes voltage outputs for AT/RH/BP, and an ID voltage
used by some Met One monitors and dataloggers to identify the sensor. The voltage outputs
are 0-2.5VDC default and can be changed to 0-1VDC or 0-5VDC.
The BX-597A uses a piezoresistive pressure sensor, a microprocessor-controlled relative
humidity module, and a platinum RTD temperature sensing element. The response of each
element is linear with negligible hysteresis. Each sensor element in the BX-597A is controlled
using an on-board microcontroller, which contains an analog-to-digital converter and non-
volatile memory for storage of factory-determined calibration coefficients. The microcontroller
polls the sensor module once per second. Measurements are temperature corrected, the
calibration coefficients applied, and the processed measurement sent out via serial
communication.
All wiring terminals on the BX-597A are protected from static-surge damage by transzorbs and
current-limiting resistors.

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5. Installation
5.1. Mounting
The BX-597A is designed for outdoor use and is supplied with an integrated solar
radiation shield and U-bolts. Install the radiation shield with the U-bolts on any vertical
or horizontal pipe up to 2 inches (IPS) in diameter. To minimize exposure to direct
sunlight, install the sensor facing north in the northern hemisphere and south in the
southern hemisphere.
5.2. Siting
Install the sensor over an open, level area at least 9 m (EPA) in diameter. The surface
should be covered with short grass or a natural earth surface where grass does not
grow. Locate sensors away from objects at a distance equal to four times the height of
the objects, and at least 30 m (EPA) from large, paved areas. Protect sensors from
thermal radiation and ensure adequate ventilation.
Standard installation heights:
1.5 m (AASC)
1.25 to 2.0 m (WMO)
2.0 m (EPA)
5.3. Wiring
The BX-597A may be ordered with a 10547 analog output cable assembly, or 10548 digital
output cable assembly (sold separately) for connection (Individual wire leads) of the BX-597A to
a data logger, signal conditioner, or programmable logic controller. A detailed wiring diagram
for each cable assembly is provided in Section 10: Wiring Diagrams.
BX-597A sensor cables for specific Met One monitors (e.g. BAM-1020 N, BAM 1022, BC-1054,
etc.) are included in accessory kits sold with the monitors. Replacement sensor cables may also
be ordered separately.

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6. Specifications
TEMPERATURE
Range: -50 °C to +70 °C (-58 °F to +158 °F)
Accuracy(1): Digital: ±0.2 °C
Analog: ±0.2 °C, +/-1 mV
Resolution: 0.01 °C
RELATIVE HUMIDITY
Range: 0 to 100 %
Accuracy(1): Digital: ±2 %
Analog: ±2 %, +/-1 mV
Resolution: 0.1 %
PRESSURE
Range: 500 to 1100 mbar (14.8 inHg to 32.5 inHg)
Accuracy(1): Digital: ±0.5 mbar
Analog: ±0.5 mbar, +/-1 mV
Resolution: 0.01 mbar
ELECTRICAL
Measurement Rate: 1 Hz
Data Storage: None
Standard Signal Output: RS-232, RS-485, 0-2.5 VDC
Optional Signal Output: 0-1 VDC, 0-5 VDC
Power Supply: 9-36 VDC, 25 mA typical @ 12 VDC
ENVIRONMENTAL
Temperature: -50 °C to +70 °C
Humidity: 0 to 100 %
PHYSICAL
Diameter: 7 in (178 mm)
Length: 8 in (203 mm)
Weight: 5 lb (2.3 kg)
(1) At 25°C

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7. Sensor Verification
To verify correct wiring and test the basic sensor operation, blow on the sensor. The
warmth and moisture in your breath should cause the temperature and relative humidity
reading to rise. The output signals can also be checked against calibrated relative humidity,
temperature, and pressure devices. Please note that relative humidity can be expected to
vary significantly over short distances and in brief periods of time.
8. Serial Communications
Serial Data Output
The output of the BX-597A is a fixed length, comma delimited, serial data stream. The
serial output is factory set for 9600 baud, no parity, 8 data bits, with 1 stop bit (N, 8, 1).
Please see appendix E for a list of supported serial commands.
Output Format Detail
The BX-597A will support only one output format. This format will use fixed length
fields but also include commas to accommodate both standard CSV formatting and
legacy programs that expect fixed length fields.
The parameter order is shown in the table below.
Field
Parameter
01
Ambient Temperature
02
Relative Humidity
03
Barometric Pressure
04
Config. & Status
05
Check Sum
The BX-597A will report data typically once per second. An example output string is
shown below.
+023.6,022.1,0974.3,U0,*nnnn
Note: when displaying the pressure in in/Hg, there will be an extra leading zero
character but the fixed length of the field will not change.

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A check sum parameter will be added to the end of the message (*nnnn). The check
sum is the addition of all the characters from the start of the message through the first
character preceding the asterisk (*). The check sum is expressed as a decimal
number. This is a 16-bit sum and should not overflow past 4 digits, given the number of
characters in the output string.
Polled Data Mode (RS232 or RS485)
The sensor can be set for polled data mode instead of continuous serial output, by
setting the serial trigger string while in terminal mode (see Section 12 for command
details).

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9. Maintenance
General Maintenance Schedule
6 –12 Month Intervals:
Inspect the sensor for proper operation per Section 7.
12 - 24 Month Interval:
Return the sensor to Met One Instruments, Inc. for factory inspection and calibration.
10. Service
The BX-597A is not field repairable and should be returned to the factory for service.
Detailed calibration & service information and pricing are available from the Met One
Instruments, Inc. Service department at [email protected] and 541-471-7111.

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11. Wiring Diagrams
PIN NO WIRE COLOR WIRE LABEL DESCRIPTION
1 Red +12VDC +9 to +36 VDC
2 Black Gnd Signal Ground
3 Orange Ana Gnd Analog Ground
4 Brown RH RH Analog Output
5 Green ID ID Voltage
6 White BP BP Analog Output
7 Blue AT AT Analog Output
Wiring Instructions (PN 10547; Analog Output)

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Wiring Instructions (PN 10548; Digital Output)
PIN NO
WIRE COLOR
WIRE LABEL
DESCRIPTION
1
Black
PWR GND
Power Ground
2
Red
+ Vin
+9 to +36 VDC
3
Blue
No Connection
Unused
4
Green
SIG GND
Signal Ground
5
White
RS-232 Tx
RS-232 Transmit
6
Brown
RS-232 Rx
RS-232 Receive
7
Orange
RS-485 -
RS-485 signal -
8
Yellow
RS-485 +
RS-485 signal +
White/Brown
Shield
Earth Ground

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12. Terminal Mode Commands
RS232 / RS485 Terminal Mode Commands
Terminal mode is activated by entering three carriage return characters within a 2
second period.
Note: Terminal mode times-out after 2 minutes of inactivity.
Successful entry into Terminal Mode will return an asterisk prompt. Typing H,h, or ? will
return a help menu:
H,h,? - Display Help Menu
H,h,? - This Help Menu
1 - Report Settings
OI - Set Output Interval
QH - Report Data Record Header
RV - Report Model/Part/Revision
RQ - Report Current Readings
PU - Pressure Units
TU - Temperature Units
Q - Quit command mode and save any changes
NOTE: The commands noted in this appendix will change both the RS232 and RS485
outputs.
1 –Report Settings
Command
Description
1
Report the settings.
Response
597A Settings Report
Firmware, 10893, R1.0.0
Serial Number, I0002
Unit ID, 1
Baud Rate, 9600
AT Unit, C
BP Unit, mbar
ID –Request or Set the Location ID

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Command
Description
ID
Request the Location ID.
ID id
Set the Location ID. This is an 3 digit numeric value in the range 1-999.
Response
Description
ID id
id –The location ID.
Example
ID<cr>
ID 001<cr><lf>
ID 03<cr>
ID 003<cr><lf>
OI –Request or Set the Output Interval
Command
Description
OI i
Set Output Interval in seconds..
Where i is the Interval. 0=No volunteered output, 1=Output every
Second. No averaging.
Response
Description
OI i
On or Off
Example
OI<cr>
OI 1<cr><lf>
OI 0<cr>
OI 0<cr><lf>
PU - Pressure Units

Page 12 BX-597A-9800 Manual Rev C
Command
Description
PU
Request the Pressure units.
PU e
Set the pressure units. Where ‘e’ is the enumerator 0-mbar,1-inHg,2-
mmHg,3-Pa
Response
Description
PU e-units
e–Concentration Units enumerator.
units –Units name string.
Example
PU<cr>
PU 0-mbar<cr><lf>
PU 1<cr>
PU 1-inHg<cr><lf>
TU - Temperature Units
Command
Description
TU
Request the Temperature Units.
TU e
Set the Temperature Units.
e–Temperature Units 0-C,1-F.
Response
Description
TU e-U
e–Temperature Unit enumerator.
u–Unit description
Example
TU<cr>
TU 0-CIN<cr><lf>
TU 1<cr>
TU 1-F<cr><lf>
RQ –Request Last Record

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Command
Description
RQ
Request the instantaneous measurement record.
Response:
Field 1 Ambient Temperature (AT).
Field 2 Relative Humidity (RH).
Field 3 Barometric Pressure (BP).
Field 4 Status
Example:
RQ<cr>
+29.9,034.4,0969.1,00,*01085
RV - Report Model, Firmware, Revision
Command
Description
RV
Request the model number, firmware part number, and revision string.
Instruments with more than one processor or programmable devices
will include more than one part number and revision on the next
subsequent lines.
Response
Description
m, p, r
m –Device model name.
p –Firmware part number.
r –Firmware revision.
Example
RV<cr>
597A, 10893, R1.0.0<cr><lf>
QH –Display Record Header
Command
Description

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QH
Report data record header.
Response
AT(C),RH(%),BP(mbar),Status