OSI ORG-815-DS User manual

OPTICAL SCIENTIFIC, INC.
ORG
-
815
-
DS USER
GUIDE
1102
-
916
ORG815DS User Guide 190809.docx
USER'S GUIDE
ORG-815-DS
OPTICAL PRECIPITATION SENSOR
Revisi n 08/09/19
OPTICAL SCIENTIFIC INC
2 Metropolitan Ct. Suite 6
Gaithersburg MD 20878 USA
Tel: [phone]
Fax: [phone]
http://opticalscientific.com

OPTICAL SCIENTIFIC, INC.
ORG
-
815
-
DS
USER'S GUIDE
1102-916 2
Rev.
8/12/2019
Revisi n Rec rd
Rev Date
Descripti n f Changes
6/28/00 Changes company name from ScTi to OSI added revision log
7/25/00 Added new mounting bracket details to Sec 2.2 updated TST-700 to
TST-800 and PSB-715 to PSB-815
05/05/10 Re-edit User’s guide to current level.
12/02/10 Make specific for ORG 815-DS
01/14/11 Restore “Q” poll and other edits per customer request
03/07/14 Add erratum notes re: firmware 42S dated 07/19/12
“A” Poll 17 byte data length in Section 4 to be ignored
Remove QwikCollect Software reference
09/08/16 Update cable to include 1102-302-4
03/15/17 Added MODBUS-RTU capability re: firmware 44s dated 03/15/17
and later
05/11/17 Corrected DC wire assignment Fig. 2.5
04/18/18 Add LDM option and Appendix A
05/16/18 Update Tech Support & Customer Service phone numbers
02/25/19 Update Figures 1.1 1.2 and 1.3
08/09/19 Heater status added on byte 20 (4th byte of status code)
Read the entire User=s Guide before proceeding
with installation or maintenance of the ORG!

OPTICAL SCIENTIFIC, INC.
ORG
-
815
-
DS
USER'S GUIDE
1102-916 3
Rev.
8/12/2019
TABLE OF CONTENTS
1 INTRODUCTION TO THE ORG-815-DS OPTICAL PRECIPITATION GAUGE ..................... 6
1.1 The ORG-815-DS Improves Your Ability To Measure Rain And Snow ......................... 6
1.2 Performance Specifications for the ORG-815-DS ........................................................... 8
1.3 Basic Sensor Description .............................................................................................. 10
1.4 Accessories For The ORG ............................................................................................ 12
2 INSTALLATION OF THE ORG-815-DS ................................................................................. 13
2.1 Siting and Installation Guidelines .................................................................................. 13
2.2 Mounting the ORG-815-DS ........................................................................................... 14
2.3 Connecting the ORG Sensor ......................................................................................... 16
2.3.1 Connecting the Digital ORG Sensor Cable 1102-302-3 ............................................ 16
2.3.2 Connecting the Digital ORG Sensor Cable 1102-302-4 ............................................ 18
3 ORG THEORY OF OPERATION ........................................................................................... 20
3.1 Overall System Theory .................................................................................................. 20
4 USER INTERFACE / ORG OPERATION .............................................................................. 22
4.1 RS-232 ORG Interface .................................................................................................. 22
4.1.1 "A" Poll Response ...................................................................................................... 24
4.1.2 "B" Poll Response ...................................................................................................... 25
4.1.3 "C" Poll Response ..................................................................................................... 26
4.1.4 "D" Poll Response ..................................................................................................... 28
4.1.5 "Q" Poll Response ..................................................................................................... 29
4.1.6 "R" "V" & "Z" Poll Responses .................................................................................. 30
4.2 ORG Operation Examples ............................................................................................. 31
4.2.1 Typical ORG-815-DS Output ..................................................................................... 31
5 MODBUS Communication ...................................................................................................... 33
5.1.1 MODBUS RTU Protocol ............................................................................................ 33
6 MAINTENANCE & TROUBLESHOOTING THE ORG-815-DS ............................................. 35
6.1 Routine Maintenance and Quick Check ........................................................................ 35
7 Appendix A - Limited Distance Modem Option ...................................................................... 37
8 TECHNICAL SUPPORT ......................................................................................................... 38
8.1 Before Contacting Technical Support ............................................................................ 38
8.2 Factory Service .............................................................................................................. 38
LIST OF FIGURES
Figure 1.1 OSI ORG-815-DS Series Optical Sensor....................................................................... 7
Figure 1.2 ORG-815-DS Dimensions .............................................................................................. 9
Figure 1.3 ORG-815-DS Major Components ................................................................................ 11
Figure 1.4 PSB Electrical Box ....................................................................................................... 12
Figure 1.5 Limited Distance Modem .............................................................................................. 12
Figure 2.1 Installing Mounting Bracket & U-Bolts .......................................................................... 14
Figure 2.2 Typical ORG Installation............................................................................................... 15
Figure 2.3 Cable 1102-302-3 ......................................................................................................... 17
Figure 2.4 PSB Connections for 1102-302-3 ................................................................................ 17
Figure 2.5 Cable 1102-302-4 ......................................................................................................... 19
Figure 2.6 PSB Connections for 1102-302-4 ................................................................................ 19
Figure 3.1 ORG 815 Sensor Block Diagram ................................................................................. 21
Figure 5.1 ModBus Example Screen ............................................................................................. 33
Figure 5.2 ModBus Master Screen ................................................................................................ 34
Figure 6.1 Comb Test Illustration .................................................................................................. 36
Figure 7.1 Limited Distance Modem .............................................................................................. 37

OPTICAL SCIENTIFIC, INC.
ORG
-
815
-
DS
USER'S GUIDE
1102-916 4
Rev.
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CAUTIONARY NOTES
Note :
Used to call attention to a special feature or procedure which
must be followed for correct operation of the equipment
Caution :
Used to call attention to a concern where damage
to the equipment or injury to personnel may occur
unless certain steps are followed
Warning :
Used to call attention to a concern where serious personal
injury or death may occur unless basic safety
procedures are follow ed
WARRANTY
Optical Scientific warrants its products to be free of defects in workmanship
and material for a period of 12 months from date of shipment. During the
warranty period OSI will repair or replace defective products at its own
expense subject to the following conditions:
1. The Buyer prepays all shipping insurance and associated costs to
return the defective item to OSI. OSI pays return shipping and insurance.
2. The product must not have experienced misuse neglect accident
or have been altered or repaired by the Buyer during the warranty period.
3. This warranty and OSI's obligation are in lieu of all other warranties.
Implied warranties shall not apply.
4. OSI is not liable for consequential or incidental damages labor
performed in conjunction with removal and replacement loss of production or
any other loss incurred because of interruption of service or production of
incorrect or incomplete weather information.
Disclaimer
Optical Scientific Inc. will not be held liable for any accident injury or
damage incurred while installing operating or servicing this equipment; or as
a result of improper installation or operation. Implementation and enforcement
of proper safety procedures is solely the responsibility of the user user
employees or contracted personnel.

OPTICAL SCIENTIFIC, INC.
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-
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-
DS
USER'S GUIDE
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Rev.
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GLOSSARY
AC Alternating Current
AGC Automatic Gain Control
AWG American Wire Gauge
ASCII American Standard Code For Information Exchange
ASOS Automated Surface Observing System
CR Carriage Return
CTRL Control
CXR Carrier Signal
CW Continuous Wave
DC Direct Current
FAA Federal Aviation Administration
LDM Limited Distance Modem
LED Light Emitting Diode
IR Infrared
MOV Metal Oxide Varistor
NEMA National Electrical Manufacturer's Association
NWS National Weather Service
ORG Optical Rain Gauge
PSB Power Supply Box
PTC Positive Temperature Thermistor
RX Receiver
OSI Optical Scientific Inc.
TX Transmitter
VDC Voltage Direct Current
ENGLISH/METRIC CONVERSION FA
CTORS
1 inch = 25.4 mm 1 mm = 0.039 in
1 foot = 0.305 m 1 meter = 3.28 ft
1 pound = 0.454 kg 1 kilogram = 2.2 lbs
ΕF = 9/5 ΕC + 32 ΕC = 5/9( ΕF – 32)

OPTICAL SCIENTIFIC, INC.
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-
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-
DS
USER'S GUIDE
1102-916 6
Rev.
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1 INTRODUCTION TO THE ORG-815-DS OPTICAL PRECIPITATION GAUGE
1.1 T HE ORG-815-DS I MPROVES Y OUR A BILITY T O M EASURE R AIN A ND S NOW
The ORG7 measures rain and snow and applies algorithms to automatically determine the
precipitation type rate and water equivalent accumulation. The ORG is vastly superior to
traditional type sensors and offers the reliability and proven performance you need!
OSI's ORG-815-DS precipitation sensor provides accurate measurement of precipitation in all
weather conditions. Designed for rugged unattended operation ORGs have been field
proven in adverse environments around the world and unlike other sensors on ocean
deployed data buoys and ships.
Optical Measurement Benefits
OSI Optical Rain Gauges are not affected by many of the environmental factors which cause
significant errors with traditional rain and snow gauges. Applications using traditional gauges
such as tipping bucket siphon weighing and electrical grid type gauges can all be upgraded
with the OSI ORG sensors. OSI ORG's have many advantages including:
Τ
ΤΤ
Τ Easy Installati n Τ
ΤΤ
Τ Wide Dynamic Range
Τ
ΤΤ
Τ High Sensitivity Τ
ΤΤ
Τ N Evap rati n r Splash Err rs
Τ
ΤΤ
Τ L w Maintenance Τ
ΤΤ
Τ W rks n Ships & Bu ys
Τ
ΤΤ
Τ Minimal Wind Effects Τ
ΤΤ
Τ Operates 24/7/365
Now with available 5-sec update rates for fine structure analysis of rain intensity!
Reliability
The electro-optical design provides for an extremely reliable sensor with a calculated MTBF
in excess of 60 000 hours. Unlike mechanical gauges which collect precipitation to measure
it the ORG has no collectors buckets or siphons to corrode or clog. The sensors use AGC
circuitry to eliminate the effects of LED output power or dirty optics. In fact sensor
performance is maintained even when over 75% of the light is blocked! Diagnostics alert the
user if the signal strength is too low for normal operation. Preventative maintenance
suggested every 6 months is as simple as cleaning the 2 optical windows on the unit.
Pr ven Techn l gy
The ORG-815-DS sensors are based on technology developed and patented by OSI. OSI
has been granted patents in the following countries: USA 4754149 UK 22001510 and
Canada 1285044. This technology is the basis for the present weather sensor supplied to the
FAA/NWS/U.S. Navy for the Automated Surface Observing System (ASOS).

OPTICAL SCIENTIFIC, INC.
1102-916
Figure
ORG
ORG
-
815
-
DS
USER'S GUIDE
7
Rev.
Figure
1.1 OSI ORG-815-DS Series Optical Sensor
ORG
7 is a registered trademark of OSI.
USER'S GUIDE
Rev.
8/12/2019

OPTICAL SCIENTIFIC, INC.
ORG
-
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-
DS
USER'S GUIDE
1102-916 8
Rev.
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1.2 P ERFORMANCE S PECIFICATIONS FOR THE ORG-815-DS
The ORG-815-DS is designed to measure rain and snow in all weather conditions.
Performance Specification
Rain Dynamic Range 0.1 to 500 mm/hr
Rain Accumulation 0.001 to 999.999 mm
Rain Accuracy 5% Accumulation
Rain Resolution 0.001 mm
Snow Dynamic Range 0.01 to 50 mm/hr water eq.
Snow Accumulation 0.001 to 999.999 mm water eq.
Snow Accuracy 10%
Snow Resolution 0.001 mm
Time Constant 10 seconds
ORG Data Update Rate Once per minute - typical Every 5 seconds - available
Electrical Specification
Supply Voltage 11 - 16 VDC
Current Drain
(Current drain depends on
ambient temperature - see
Section 1.3 for details)
400-800 ma
Fusing User supplied 1.0 A Slow Blow
Signal Output RS-232
User Heater Control n/a
Transient Protection All power and signal lines protected by MOV

OPTICAL SCIENTIFIC, INC.
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-
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-
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USER'S GUIDE
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Environmental Specification
Temperature -40 to 50ΕC (-40 to 122ΕF)
Humidity 0-100%
Precipitation/Dust NEMA-4 type protection
Physical Specification
Size 763 mm L x 254 mm W x 102 mm H
Weight 3 kg w/o cables
Cable Length 15 meter
Figure 1.2 ORG-815-DS Dimensions

OPTICAL SCIENTIFIC, INC.
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-
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-
DS
USER'S GUIDE
1102-916 10
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1.3 B ASIC S ENSOR D ESCRIPTION
Precipitation is measured by detecting the optical irregularities induced by drops falling
through an infrared optical beam. These irregularities known as scintillation have
characteristic patterns which are detected by the sensor and converted to precipitation rate.
OSI's optical precipitation sensors measure rain and snow by detecting the optical
irregularities induced within the sample volume by precipitation particles falling through a
beam of partially coherent infrared light. These irregularities are known as scintillation. The
twinkling of stars is a familiar example of scintillation. By detecting the intensity of the
scintillations which are characteristic of precipitation the actual rainfall rate can be
determined.
The ORG consists of 1) a head frame which contains the transmit head receive head and
electronics and 2) a 15 meter long power/signal cable P/N 1102-302. The small box
(transmit) contains an IRED diode and lens with disk heater. The large box (receive) contains
a photodiode lens with aperture slit disk heater electronics external thermistor probe and
connector for the signal/power cable. All wiring between the transmit and receive heads is
within the frame.
The transmit and receive lenses are heated by self-regulating positive temperature coefficient
(PTC) thermistor disks to a point above ambient temperature to reduce dew frost and snow
buildup on the lenses. Depending on the ambient temperature the current drain for the lens
heaters can change more than 200 ma.
Data input and output are RS-232 digital expressed in ASCII characters
The ORG is completely sealed from water intrusion at the factory. Care should be taken to
maintain the unit’s watertight integrity.
Note :
The O G contains no user-serviceable parts - do not attempt to open it!
Doing so will compromise watertight seals and void any warranty.

OPTICAL SCIENTIFIC, INC.
ORG
-
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-
DS
USER'S GUIDE
1102-916 11
Rev.
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Caution :
Do NOT drill holes in any portion of the O G frame! Doing so will void the warranty and may
allow water to enter the enclosure!
Figure 1.3 ORG-815-DS Major Components

OPTICAL SCIENTIFIC, INC.
1102-916
1.4 A CCESSORIES F OR T
HE
Several accessories are available from
Contact the Sales Office for more information.
Electrical B x
The PSB-
815 Power Supply Box
NEMA-
4 type enclosure with a hinged
door for easy access.
It houses a
universal input AC/
DC power supply
terminal strips for connecting the ORG to
the customer’s equipment
.
Figure 1.4 shows a typical PSB box.
PSB box operates
with 100
line voltage.
Limited Distance M dems (LDM)
A pair of LDMs is available if the distance
between the ORG-
815 and computer is
more than the RS-
232 specified distance
of 100
feet. One LDM is installed inside
the WIVIS power supply box and the
other is connected to the user’s
computer. The LDMs operate over 2
unconditioned twisted wire pairs up to 14
km (9 mile) if the wire gauge is 19 AWG
or larger. Detailed description of th
is in Appendix A.
ORG
-
815
-
DS
USER'S GUIDE
12
Rev.
HE
ORG
Several accessories are available from
OSI for the ORG.
Contact the Sales Office for more information.
815 Power Supply Box
is a
4 type enclosure with a hinged
It houses a
DC power supply
and
terminal strips for connecting the ORG to
.
Figure 1.4 shows a typical PSB box.
The
with 100
to 230 VAC
Figure 1.4
PSB Electrical Box
Limited Distance M dems (LDM)
A pair of LDMs is available if the distance
815 and computer is
232 specified distance
feet. One LDM is installed inside
the WIVIS power supply box and the
other is connected to the user’s
computer. The LDMs operate over 2
unconditioned twisted wire pairs up to 14
km (9 mile) if the wire gauge is 19 AWG
or larger. Detailed description of th
e LDM
Figure 1.5
Limited Distance Modem
USER'S GUIDE
Rev.
8/12/2019
PSB Electrical Box
Limited Distance Modem

OPTICAL SCIENTIFIC, INC.
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-
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-
DS
USER'S GUIDE
1102-916 13
Rev.
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2 INSTALLATION OF THE ORG-815-DS
2.1 S ITING AND I NSTALLATION G UIDELINES
The ORG may be installed almost anywhere outdoors but an area free and clear of
obstructions and contamination sources will help insure good sensor performance.
In general ORG should be located on level or slightly sloping ground where the
sensor site will be exposed to the same environment as the area around it. Ideally the
area around the site should be free of buildings trees and other obstructions.
OSI recommends that the siting and installation follow the general guidelines
established by the Office of the Federal Coordinator for Meteorology (OFCM). The
Federal Standard for Siting Meteorological Sensors at Airports OFCM document #
FSM-S4-1987 makes the following recommendations:
1. Distance fr m Obstructi ns - The distance between the sensor and obstructions
such as trees or buildings should be at least 2 times the height of the obstruction on all
sides. For example if a 20 meter high tree is located alongside the ORG the ORG
should be at least 40 meters away from the tree. This restriction reduces the affects of
wind turbulence created by the nearby obstruction and makes the ORG precipitation
measurement more representative. Do not locate the ORG where tree branches or
wires will hang over the sensor!
2. Separati n fr m Turbulence & C ntaminati n S urces - Do not mount the
ORG near building exhaust vents strobe lights or sources of smoke or steam. Where
possible locate the ORG as far away from runways and roads as possible to reduce
optics fouling from wind blown road dirt. An ideal minimum distance is at least 30
meters.
3. Sens r Height, Rigidity, Verticality, and Orientati n - The OFCM recommends
that the present weather sensor be mounted at a height of 10 feet (3 m). This height is
not always possible due to constraints imposed by the site. Mounting the ORG head
lower than 2 m or higher than 5 m is not generally recommended.
Τ
ΤΤ
Τ The ORG installation must be rigid so that wind-induced vibration does not cause
false alarms. This can be accomplished by mounting the sensor to a thick wall pipe
such as "Schedule 40" type or to a rigid boom arm of 1 meter length or less. Mounting
the ORG on the top of a building is acceptable if it is located near the center of the
building away from the wind turbulence that may occur near the edges.
Τ
ΤΤ
Τ The sensor head must be mounted vertical within +/- 2 degrees so that the line
aperture on the in-beam lens is horizontal.
Hint - Standing at the ORG site take a picture in each direction (north east
south & west) to record the topography and obstructions for future reference.

OPTICAL SCIENTIFIC, INC.
1102-916
Τ
ΤΤ
Τ
Sens r head m unted 2
Τ
ΤΤ
Τ Rigid m unting p le
Τ
ΤΤ
Τ Receiver
lens aperture h riz ntal t +/
Τ
ΤΤ
Τ
N verhanging trees, wires, r r f lines
Τ
ΤΤ
Τ Distance be
tween ORG and cl sest bstructi n at least 2 times bstructi n height
Τ
ΤΤ
Τ
As far fr m r ad, runway, and c ntaminati n s urces as p ssible
2.2 M OUNTING THE
ORG
ORG-815-DS
installation is simple
The ORG is packed in one (1) heavy walled corrugated carton.
sensor head 15-
meter cable
and any accessories that were ordered.
Report any shortage or
User Supplied Items Required
Τ
ΤΤ
Τ
M unting p le r t wer t install sens r head.
Τ
ΤΤ
Τ A c pper-
clad gr und r d and large diameter c pper wire if needed t pr pe
gr und the ORG per l cal electrical c des.
Do NOT drill holes in any portion of the O G head!
Step
-
By
-
Step Installati n
1.
Carefully choose the site using the guide
2. Attach the 2 ea U
-
mounting plate with the 1/4
locking nuts with the stainless
mounting bracket sandwiched between
as shown in Figure 2.
ORG to a vertical pipe install the U
bolts horizo
ntally as shown.
to a horizontal pipe or boom arm install
them vertically using the same holes.
Do not tighten the nuts completely until
the sensor head is installed on the pole.
3.
Attach the sensor head to the mounting pole using the two (2) U
the U-
bolt nuts completely until the head is oriented.
ORG
-
815
-
DS
USER'S GUIDE
14
Siting Guidelines T Remember
Sens r head m unted 2
-5 meters high
lens aperture h riz ntal t +/
- 2 degrees
N verhanging trees, wires, r r f lines
tween ORG and cl sest bstructi n at least 2 times bstructi n height
As far fr m r ad, runway, and c ntaminati n s urces as p ssible
ORG
-815-DS
installation is simple
. A
few precautions will insure good sensor performance.
The ORG is packed in one (1) heavy walled corrugated carton.
Included in the carton are the
meter cable
grounding wire U-Bolts (2)
Mounting Bracket User
and any accessories that were ordered.
When opening the carton be carefu
damage to the shipping company and OSI
within 3 days.
User Supplied Items Required
M unting p le r t wer t install sens r head.
clad gr und r d and large diameter c pper wire if needed t pr pe
gr und the ORG per l cal electrical c des.
CAUTION :
Do NOT drill holes in any portion of the O G head!
Doing so will void the warranty and may
allow water to enter the enclosure !
Step Installati n
Carefully choose the site using the guide
lines in Section 2.1.
-
bolts to the ORG
mounting plate with the 1/4
-20 hex
locking nuts with the stainless
-steel
mounting bracket sandwiched between
1. To mount the
ORG to a vertical pipe install the U
-
ntally as shown.
To mount
to a horizontal pipe or boom arm install
them vertically using the same holes.
Do not tighten the nuts completely until
the sensor head is installed on the pole.
Figure 2.1 Inst
alling Mounting Bracket & U
Attach the sensor head to the mounting pole using the two (2) U
-
bolts.
bolt nuts completely until the head is oriented.
USER'S GUIDE
Rev.
8/12/2019
tween ORG and cl sest bstructi n at least 2 times bstructi n height
few precautions will insure good sensor performance.
Included in the carton are the
Mounting Bracket User
=s Guide
When opening the carton be carefu
l to avoid spilling.
within 3 days.
clad gr und r d and large diameter c pper wire if needed t pr pe
rly
Doing so will void the warranty and may
alling Mounting Bracket & U
-Bolts
bolts.
Do not tighten

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-
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-
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4. Tighten the U-bolt nuts when the orientation is correct. (Do not over tighten the bolts or
the mounting plate may warp)
5. Plug the P3 end of the P/N 1102-302-3 cable into the J3 connector on the bottom of the
ORG sensor head.
6. If required connect a large diameter (8-12 AWG) ground wire to the 1/4-20 ground stud
on the bottom of the ORG sensor head using the hardware supplied with the ORG.
7. Secure the head cables to the pole every 1 meter using tie-wraps or other straps.
8. A typical installation is shown in Figure 2.2.
Figure 2.2 Typical ORG Installation

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-
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2.3 C ONNECTING THE ORG S ENSOR
ORG connecting cable design was upgraded in August of 2016.
• The existing cable 1102-302-3 is superseded by 1102-302-4.
• The cable has been changed from shielded twisted pair to shielded bundle.
• Color code assignments have also been changed.
Connect the ORG sensor according to the information in the following sections.
2.3.1 C nnecting the Digital ORG Sens r Cable 1102-302-3
Connections are made to the free end of the ORG cable for all power signal and control
functions.
The normal installation of the ORG requires a fused 12 VDC power source and junction box
at the end of the cable. The customer may choose to provide these items or the ORG sensor
may be purchased with an Optical Scientific Inc. ORG 815 Power Supply Box (PSB).
In either case proper wiring configuration is shown in the following pages.
Connect the wires in the ORG cable as shown in the table below and in Figure 2.3 and 2.4
Wire Pair Function DB9 Connector
(if used)
DB25 Connector
(if used)
Red
Black
+ 12 VDC
DC Power Supply DC Power Supply
+ 12 VDC Common
Yellow
Black
+ 12 VDC Heater
DC Power Supply DC Power Supply
+ 12 VDC Heater Common
Green
Black*
Sensor TX
Pin 2 of DB9 Pin 3 of DB25
TX Common
Blue
Black*
Sensor RX
Pin 3 of DB9 Pin 2 of DB25
RX Common
* both Black (TX/RX Common) from Green
and Blue pair are spliced together to make
single signal ground reference
Pin 5 of DB9 Pin 7 of DB25
Black Cable Shield Earth Ground Earth Ground
Note :
Signal and power lines are protected from surge damage within the O G sensor head. It is
recommended that surge protection be provided at the user equipment end as well.

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1102-916
emember, the
Do not apply 110/220 VAC to the ORG cable!
OPTICAL SCIENTIFIC, INC.
ORG
-
815
-
DS
17
arning :
emember, the
O G-815-DS requires 12 VDC power.
Do not apply 110/220 VAC to the ORG cable!
Figure 2.3 Cable 1102-302-3
Figure 2.4 PSB C nnecti ns f r 1102-302-3
DS
USER'S GUIDE
Rev.
8/12/2019

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-
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-
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Rev.
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2.3.2 C nnecting the Digital ORG Sens r Cable 1102-302-4
Connections are made to the free end of the ORG cable for all power signal and control
functions.
The normal installation of the ORG requires a fused 12 VDC power source and junction box
at the end of the cable. The customer may choose to provide these items or the ORG sensor
may be purchased with an Optical Scientific Inc. ORG 815 Power Supply Box (PSB).
In either case proper wiring configuration is shown in the following pages.
Connect the wires in the ORG cable as shown in the table below and in Figure 2.5 and 2.6
Wire Function DB9 Connector
(if used)
DB25 Connector
(if used)
Red + 12 VDC DC Power Supply DC Power Supply
Black +12 VDC Return DC Power Supply DC Power Supply
Yellow + 12 VDC f/Heater DC Power Supply DC Power Supply
Gray Heater +12VDC Return DC Power Supply DC Power Supply
White Sensor TX Pin 2 of DB9 Pin 3 of DB25
Green Sensor RX Pin 3 of DB9 Pin 2 of DB25
Brown Sensor TX/RX Signal Gnd. Pin 5 of DB9 Pin 7 of DB25
Black Cable Shield Earth Ground Earth Ground
Note :
Signal and power lines are protected from surge damage within the O G sensor head. It is
recommended that surge protection be provided at the user equipment end as well.
arning :
emember, the O G-815-DS requires 12 VDC power.
Do not apply 110/220 VAC to the ORG cable!

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OPTICAL SCIENTIFIC, INC.
ORG
-
815
-
DS
19
Figure 2.6 PSB C nnecti ns f r 1102-302-4
Figure
2
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5
Cable 1102
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302
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DS
USER'S GUIDE
Rev.
8/12/2019

OPTICAL SCIENTIFIC, INC.
ORG
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815
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DS
USER'S GUIDE
1102-916 20
Rev.
8/12/2019
3 ORG THEORY OF OPERATION
3.1 O VERALL S YSTEM T HEORY
The ORG is an electro-optical sensor consisting of optics analog signal processing
electronics and a digital microprocessor.
A block diagram of the ORG-815-DS Sensor is shown in Figure 3.1. The sensor consists of:
- Transmit modulator and IR Light Emitting Diode (TX)
- Transmitter optical lens assembly
- Receiver optical lens assembly
- PIN photo detector and preamplifier (RX)
- Digital Signal Processor (DSP)
- Temperature probe
- Microprocessor and communications subsystem
The ORG uses an infrared light emitting diode (IRED) as a light source. The IRED is
modulated to eliminate interference in the system caused by background light. The IRED has
a very long lifetime is relatively low power invisible to the eye and presents no radiation
hazard to the user.
The IRED is housed in the smaller of the two boxes the entire subassembly being referred to
as the transmitter or source. The IRED is driven by a square wave continuous wave (CW)
modulation circuit at 50 percent duty cycle and at a fixed frequency. A lens is used to
collimate the IRED's CW modulated light into a slightly diverged beam. The transmit and
receive lenses are both heated by a self-regulating positive temperature coefficient (PTC)
thermistor disc to a point above ambient temperature to reduce dew and frost on the lenses.
The larger rectangular box houses the receive optics DC regulator the AGC signal
processing electronics temperature probe and microprocessor. The receive lens focuses the
transmitted light onto a photo diode. The scintillations in light intensity are thus detected and
amplified. A wide dynamic range Automatic Gain Control (AGC) circuit normalizes the
precipitation induced scintillation signal to the (CW modulated) carrier. Thus errors from
variations in the source intensity caused by LED aging or dirt on the lenses are eliminated.
The demodulated scintillation signal is then further filtered processed and averaged. The
statistical average of the measured scintillation signals give an accurate measurement of the
instantaneous rain rates.
For the digital versions a microprocessor uses an adaptive baseline technique to continually
optimize the sensitivity of the ORG. This technique ensures that the ORG sensitivity is not
affected by normal atmospheric turbulence and it minimizes the chance of false alarms (i.e.;
reporting precipitation when none occurs). Using the scintillation signal and temperature
probe data the processor determines the precipitation type and calculates the total water
equivalent by the following formula:
W (mm) = k * RR (mm/hr) * Time (hour)
where RR is the precipitation intensity and k is a constant dependent on the ambient
temperature as follows:
For T > 30 C k = 1
For T < -40 C k = 0.607
For -40 C < T > 30 C k = exp{(T - 3) / 12}