Omega Products WMS-16-PN Installation Manual
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INTRODUCTION
disk for permanent storage using the options available on the
main menu.
Congratulations on your purchase of a WMS-16 Weather
Station, and welcome to the world of modular, user friendly
weather data collection. The WMS-16 has been carefully
designed with the user in mind, and we are confident that it
will provide you with convenient and accurate weather data
for years to come.
The WMS-16 is a state-of-the-art, microprocessor-based
weather station that provides capabilities unequaled in
similarly priced instruments. In its standard configuration,
measurements for wind speed, direction, temperature,
humidity, and precipitation are collected and processed by the
control module.
Any, or all, of these weather parameters can be included by
simply adding the appropriate sensors. The exact
configuration is determined by the user based on demands of
the intended application.
Data Output, Display, and Logging
Real-time weather data is output by the WMS-16 over its RS232 interface, and this data can be readily viewed by either
using a PC based communications program or with the
optional software for the WMS-16. In addition to current
weather information, the WMS-16’s data logging capability
allows up to 45 days of data taken at 15 minute intervals to be
stored in memory for later retrieval.
Special consideration has been given in the design of the
WMS-16’s display of current weather data to ensure ease of
understanding by the first-time or casual user.
When retrieved for viewing, the logged data is displayed as
date and time stamped single line, tab delineated entries.
Logged data can be retrieved in either hourly or daily blocks.
For permanent storage, the data logged by the WMS-16 can be
copied to a magnetic disk. The format of the logged data has
been designed to be compatible with most commercial
spreadsheet software coma delineated (Excel, Lotus 1-2-3, and
Quatro Pro among others).
The Control Module
The heart of the WMS-16 is the control module. The control
module conditions and processes the signals generated by the
attached sensors and outputs them via the RS-232 interface at
a default rate of 9600 bits per second other bit rates are user
selectable.
In addition to the RS-232 interface connector, connections are
provided on the control module’s rear panel for all of the
weather sensors.
Power is provided by an external 12V source, and the WMS16 comes equipped with a 12V wall transformer for powering
the station from a standard 110V outlet. A 12V battery can be
wired into the module to provide emergency power in the
event of a loss of main power. This battery will provide
backup power allowing data logging and output to continue
uninterrupted. A fully charged 12V, 7 amp-hour battery will
run the WMS-16 for three to four days.
Sensors
Current Observations
This display is a one-page report of current weather
conditions, with each parameter clearly labeled and readily
located on the screen.
In addition to the measured parameters, the
WMS-16 also calculates values for wind chill and dew point
based on the combination of weather factors that govern those
characteristics. The WMS-16 also reports specific aspects of
the measured parameters, including peak wind speed, wind
direction variation, hourly temperature change, maximum and
minimum daily temperature, barometric pressure changes,
maximum and minimum daily pressure, relative humidity
change and daily and monthly precipitation accumulation.
Data Logging
The time interval between recordings is user determined for
periods ranging from one minute to sixty minutes. This logged
data can be retrieved for display or copied to a floppy or hard
WMS-16 Weather Station Operator’s Manual 1
The standard sensors used with the WMS-16 have been
designed to be rugged, compact, and light-weight. They
interface directly to the control module without the need for
additional signal conditioning. These sensors are accurate and
reliable, and any combination can be used.
Wind
The wind sensor combines a three-cup anemometer and a
wind vane on a single axis. The anemometer is a contact-type
wind sensor which when rotated by the wind, triggers a series
of momentary switch closures that are directly related to wind
speed.
The wind vane uses a potentiometer to sense direction
changes. Depending on the position of the potentiometer
wiper, an analog voltage is output that corresponds to the
position of the vane. By orienting the vane North (360°)
during installation, wind can be easily calculated from the
output voltage. The resolution of the wind vane is 1° (azimuth
display), or 16 compass points (cardinal points display).
Barometric Pressure
Barometric pressure is sensed using a piezoresistive sensing
element. This element responds to changes in barometric
pressure with a corresponding change in resistance. This
resistance is converted to a voltage from which the
microprocessor calculates the barometric pressure at the
elevation at which the barometer is located.
Since air pressure varies with elevation, the barometric
pressure must be set for the elevation at which the barometer
is installed. This value is set simply using a screwdriver.
Instructions are provided in the Installation Section of this
manual.
Temperature and Relative Humidity
The WMS-16 is designed to accommodate a combination
temperature/ relative humidity sensor. For maximum
accuracy, the sensor should be isolated from the effects of
sunlight a factor that can cause misleading temperature and
humidity measurements. The Model WMS-16-THS Naturally
Aspirated solar shield is provided to give this protection.
Temperature is sensed using a thermistor element whose
resistance changes in response to temperature fluctuations.
Relative humidity is sensed by changes in the dielectric
constant of a thin polymer film as it absorbs moisture or sheds
it to the surrounding air.
Rain
The rain gauge used with the WMS-16 is a traditional tipping
bucket design. Resolution is 0.01 inches.
Using the Data
Once the weather data generated by the WMS-16 has been
logged and saved-either within the control module or on an
external media-it can easily be manipulated by a number of
commercially available software packages. The format of the
columnar, coma-delimited data was carefully designed to
make it compatible with the most widely used spreadsheet
programs. The data can be imported easily into these programs
and from there analyzed or manipulated, making the
information generated by the WMS-16 much more than
simply a collection of numbers.
A number of enhancements to the WMS-16 are planned for
the future that will make the WMS-16 even more responsive
to your needs. The EEPROM in which the operating firmware
is stored can be electronically updated to simplify future
firmware upgrades.
WMS-16 Weather Station Operator’s Manual 2
INSTALLATION
Figure 1
Installation of the WMS-16 is simple and straight forward,
thanks to its modular design and terminal-strip connections.
Figure 1 shows the control module’s rear panel and the
locations of the various connections. An auxiliary battery can
be used as an alternative power input if you do not intend to
use the provided wall transformer.
Installation Considerations
Prior to installing the WMS-16, you should be aware of
several important points that must be taken into consideration
when choosing a site for the control module and sensors.
Control Module
The control module should be located as close as possible to
the computer that will be used to communicate with the
WMS-16. RS-232 communications (the communication
protocol used with the WMS-16) is designed for use over
short distances, and the cable connecting the control module to
the computer should not be longer than 30 feet (10 meters).
Longer lengths may work.
If this arrangement is not feasible and a longer cable run is
required, an RS-232 to RS-422 converter can be added to
allow longer cable runs.
Barometric Pressure Module
The Barometric Pressure Module is designed to be mounted
indoors. This arrangement assumes that the barometric
pressure indoors and outdoors is equal. The Barometric
Pressure Module is provided with a short cable that connects
directly to the control module.
WMS-16 Weather Station Operator’s Manual 3
Tripod Tower
RS-232 Interface
The five foot tripod tower provided for the
WMS-16 is constructed of steel tubing for durability and
strength. Horizontal bracing is a feature of the tripod tower.
The tower’s foot brackets can be bolted onto a concrete
foundation or a wooden platform. The wind speed and
direction sensor mounts on top of the mast. The solar radiation
shield with 6” mast and coupling are made to clamp on the
five-foot aluminum mast. The rain gauge mounting arm is
supplied with a u-bolt to clamp onto this mast. For stability, it
is recommended that the mast be inserted into both of the
collar clamps. Guy kits are recommended for areas of high
winds and ground kits are recommended for areas with
lightning activity.
Lightning Protection and Grounding
Caution: When installing the wind sensor, make sure that the
sensor and cable are well clear of any power lines.
A lightning protection ground screw is located on the control
module’s rear panel. It is the path to ground for all of the
lightning protection circuitry in the WMS-16. Connect this
screw to a grounded outlet or water pipe. In areas subject to
sever lightning activity, we recommend that you install a
grounding rod.
The WMS-16 is an interactive device that not only outputs
data but is capable of responding to user commands. These
commands are entered through the computer which also
displays the current data and any additional data requested by
the user. Communications between the user and the WMS-16
is accomplished using RS-232 communications protocol
designed for short-distance use.
The interface cable that connects the control module to the
computer is terminated with a sub-miniature “D” connector.
Depending on the connectors available on your computer’s
serial port a 25-pin to 9-pin adapter may be required.
Connect the RS-232 cable between the control module and the
computer’s serial port. (number 1 or 2)
Certain communications parameters (number of data bits,
parity, etc.) must be specified in the computer to enable the
two devices to communicate with one another. They should be
set as follows:
Baud rate 9600
Data Bits 8
Stop Bits 1
Parity None
Handshaking Xon/Xoff
Power Connections
The WMS-16 can be operated from either standard 110VAC
outlet, or from an external 12V battery.
Standard Outlet
A wall transformer is provided with the unit for operating
from an 110VAC outlet. An optional wall transformer is
available for operating from a 220V/50Hz power source. The
wall transformer provides a nominal 12VDC.
External Battery Power
An auxiliary power connection is provided on the rear panel of
the control module for connecting an external 12VDC battery.
This battery can be used as the main power source. Remember
though, that if the auxiliary power connector is used for main
power, there will be no backup power source. A fully charged
12V, 7 amp-hour battery will run the WMS-16 for three to
four days. With the backup battery in place, the WMS-16 will
continue collecting and logging data during a power outage.
The WMS-16’s main memory has a lithium battery back up
and the setup parameters and any stored data will be saved if
the primary power source is interrupted.
Under this protocol the computer sends ASCII character DC3
(19 decimal, 13H) to the WMS-16 to halt its transmission, and
DC1 (17 decimal, 11H) to resume.
Testing the Connection
Once the WMS-16 is connected to the computer, the
connection can be tested by briefly disconnecting and then reconnecting the main power at the control module.
1. Unplug the wall transformer from the control
module’s rear panel.
2. Leave power disconnected for several seconds,
then plug the power cable in again.
If the RS-232 connection is sound, an Omega header and/or
the Software version will appear on the screen (Figure 2).
Omega WMS-16 Modular Weather Station
© Omega 2000
Software Version: 2.3.000102
Figure 2
WMS-16 Weather Station Operator’s Manual 4
Sensor Installation
Install the sensors in their chosen locations, bearing in mind
the installation considerations noted earlier. Run cables from
the sensors to the control module location, with no cable
exceeding the maximum allowable length listed in Table 1.
5.Temperature WMS-16T A5
6.Temperature WMS-16T A6
7.Wind Direction WMS-02 A7
Add sensor [A], delete sensor [D], or quit [Q]:
When the sensors have been installed and the cables run,
connect and test them as described in the following sections.
Refer to Figure 1 for connection locations on the control
module’s terminal strip.
Table 1: Maximum Sensor Cable Lengths
Sensor Max. Cable Length
Wind 250 (76m)
T/RH 250 (76m)
Rain 900 (275m)
Barometer 10’ (3m)
Solar Radiation 100 (33m)
WMS-16 Module Setup
The WMS-16 Module has been configured at the Omega
factory to work with the following sensors:
The instructions in Appendix 1 direct you through the
enabling procedure for each type of sensor should any sensor
that you plan to use not be enabled.
Wind Speed and Direction
Wire the wind sensor’s signal cable into the terminal strip on
the control module’s rear panel as shown in Figure 1. Call up
the main screen (Figure 3.) on the display terminal by pressing
“Esc” for main menu. Press “2” for Current Observations at
the main menu. Then press “1” for observation display
(Figure 4).
Turn the Anemometer cups by hand and note the wind speed
displayed on the screen. This value should change as you spin
the cups.
Turn the wind vane so that the tip is aligned with the two
vertically positioned set screws on the base of the sensor. The
wind direction shown on the screen should indicate North (0°).
Turn the vane in increments around the full 360°, noting the
change in the wind direction readings. These should agree
with the present position of the vane.
© Omega 2000
1.Wind speed and Direction
2.Barometer
3.Temperature and Relative Humidity
4.Rain Gauge
To verify the sensor setup press “Esc” to go to the main menu.
Then select item 1. Station setup. From the Setup Menu select
6. Add or remove sensors. Press “Y” to continue. The sensor
configuration page will appear showing all of the presently
enabled sensors. It shows the sensor models and calibration
factors.
Omega WMS-16 Modular Weather Station
© Omega 2000
Sensor Configuration
Sensor Type Model Input Calibration
1.Wind Speed WMS-01/02 P1
2.Precipitation All Models P3 0.0100
3.Pressure WMS16-BP A2
4.Humidity 225-050Y(U)/40 A4
Main Menu
1. Station setup
2. Current observations
3. Display log by hours
4. Display log by days
5. Data download
6. Clear logging memory
Enter your selection (1-6):
Figure 3 Main Screen
Barometric Pressure Module
Wire the three wires of the barometric pressure module into
the terminal strip on the WMS-16 module as shown in Figure
1.
Since pressure varies with elevation, the barometric pressure
sensor must be adjusted to read correctly at the elevations at
which it is installed. This is done using the offset adjustment
screw located on the side of the barometric pressure module.
WMS-16 Weather Station Operator’s Manual 5
While watching the main screen, slowly turn the offset
To set barometric pressure offset, for sea level, you must first
obtain a reliable barometric pressure for your location. The
barometric pressure range is 28.25 to 30.75. This can be found
by contacting the nearest airport or weather service facility.
Nominal barometric pressure is 29.6 inches of mercury.
Call up the main screen (Figure 4) on the display terminal by
pressing “Esc” for main menu. Press “2” for Current
Observations at the main menu. Then press “1” for
observation display (Figure 4).
Station: Omega WMS-16 01/26/2000 11:07:35
===============================================================
WIND SPEED: 3.9mph, peak windspeed 7.8mph during past 10 min.
DIRECTION: WNW, 299deg, varying 48deg during past 10 min.
WINDCHILL: +52F
CURRENT TEMPERATURE: +51.6F, +0.2F change during past hour
TODAY'S HIGH/LOW: +53F at 09:42, +39F at 07:12
DEW POINT: +45F
AUX TEMPERATURE: +0.0F, +0.0F change during past hour
adjustment screw. Clockwise will decrease the pressure
reading. You may have to turn the adjustment 3 to 10
revolutions before the display starts to change. Turn the pot
slowly in single turn increments, then wait for the screen to
update, every five seconds. If the value is moving away from
the correct value obtained above, turn the screw in the
opposite direction. Continue turning the screw
until the displayed value agrees with the value
obtained from the airport or weather service.
SOLAR RADIATION: 0W/m^2
BAROMETER: 29.08in, +0.16in change during past 3 hours
TODAY'S HIGH/LOW: 29.08in at 10:54, +28.80in at 00:43
RELATIVE HUMIDITY: 78%, +4% change during past hour
PRECIPITATION:
Since Last Log: 0.00in
Today: 0.00in
This Month: 0.00in
(Press Esc for main menu)
Figure 4 WMS-16 Observation Screen
Temperature/Humidity Sensors
Wire the cable from the Temperature/Humidity sensor into the
terminal strip on the WMS-16 module as shown in Figure 1.
Call up the main screen (Figure 3) on the display terminal by
pressing “Esc” for main menu. Press “2” for Current
Observations at the main menu. Then press “1” for
observation display (Figure 4).
To simulate a change in temperature and humidity, lean close
to the sensor (or to the solar shield) and breathe onto the
sensor until you see a corresponding increase in the displayed
temperature and humidity values.
Obtain current values for temperature and humidity from the
nearest airport or weather service facility, and see that the
values shown on the main display agree approximately with
them.
WMS-16 Weather Station Operator’s Manual 6
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