User`s Manual Model 6490 - I Present Weather Sensor
Contents
1. Valid values are 99 to 999 Overflows and underflows are represented as 999 and 99 respectively 20 Model 6490 I Present Weather Sensor User s Manual 6 ttt is a three byte ASCII numeric field indicating the temperature indicated by the probe on the bottom of the enclosure It is for diagnostic purposes and should not be used as a true meteorological temperature The valid values are 99 to 999 in units of degrees Fahrenheit Note that a value of 99 indicates a defective or missing temperature probe 21 Model 6490 I Present Weather Sensor User s Manual 5 3 DATA INTERPRETATION 5 3 1 Weather Codes The poll response contains weather codes formatted in NWS type format The latest one minute weather code ww is found in bytes 3 and 4 immediately following the W place marker NWS WX Code Description WX Code NWS WX Code Description Light Drizzle I Light Ice Pellet Moderate Drizzle IL Moderate Ice Pellet Heavy Drizzle I Heavy Ice Pellet Light Rain Light Hail Moderate Rain Moderate Hail Heavy Rain Heavy Hail Light Precipitation No Precipitation Moderate Precipitation Start up code Heavy Precipitation Error Condition Light Snow Lenses need to be cleaned Moderate Snow only reported when no Heavy Snow precip Freezing Drizzle Freezing Rain ce 9 The _ underline character above represents an ASCII underline character The code will be output in this and other data fields during the fir2. been operating and not reset by a power interruption for at least 5 minutes If the status fields are not all zeros refer to Section 5 3 2 for an interpretation of the possible problem Hint If the Quick Check values do not appear to be correct record at least 10 minutes of the complete status string and fax them to the All Weather Inc Customer Service department 916 928 1165 for evaluation Include the weather conditions at the site during the period in question air temperature wind speed type of precipitation if any etc 28 Model 6490 I Present Weather Sensor 7 SPECIFICATIONS User s Manual Parameter Specification Present Weather Codes Reported gt 50 NWS and WMO codes Rain Dynamic Range 0 1 3000 mm h Rain Accumulation 0 1 999 999 mm Rain Accumulation Resolution 0 001 mm Rain Accumulation Accuracy 5 Snow Dynamic Range 0 01 300 mm h water equivalent Snow Accumulation 0 001 999 999 mm water equivalent Snow Accumulation Resolution 0 001 mm Snow Accumulation Accuracy 10 Data Update Rate Once per minute Serial Output RS 485 Output Format ASCII characters Baud Rate 4800 bps Serial Port Parameter Setting Supply Voltage 8 N 1 8 data bits no parity 1 stop bit Power Requirements 115 230 V AC 50 60 Hz 50 VA Transient Protection AC power and RS 485 signal lines fully protected Environmental Opera
3. not always possible because of constraints imposed by the site Mounting the sensor head lower than 2 m or higher than 5 m is not generally recommended For AWOS installations All Weather Inc recommends that the sensor head be mounted on a pipe If the pipe mast is more than 5 cm 2 in diameter a mast coupling with a diameter of 5 cm 2 or less should be placed on top of the pipe The 6490 I may also be installed on the sensor tower at a height of 10 ft above the tower base Install the controller box on the tower close to the AWOS Data Collection Processor box When installing on the Model 8518 A Foldover Tower mount the Present Weather Sensor to the hinged side of the tower The 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 1 m in length or shorter The Present Weather Sensor may be mounted on the top of a building is acceptable if it located near the center of the building away from the wind turbulence that may occur near the edges Model 6490 I Present Weather Sensor User s Manual The sensor head must be mounted vertical within 2 degrees so that the line aperture on the in beam lens is horizontal 4 The sensor head is generally oriented with the transmitter head on the north side in the Northern hemisphere so that the receiver optics face north Align the sensor hea
4. rail connector and the Serial Interface Processor connect the WHITE RS 485 signal cable to terminal 6 connect the BLACK RS 485 signal cable to terminal 7 and connect the RED GND signal cable to terminal 8 of the DIN rail terminal block Feed the free end of the shielded RS 485 cable through the serial cable gland shown in Figure 8 Strip and tin the ends of the wires Route the cable through a cable gland on the DCP and connect the three wires inside the DCP to TB4 pins 1 WHITE 2 BLACK and 7 RED Ensure that none of the wires are stressed then hand tighten the gland seals on the DCP enclosure and on the electronics enclosure Connecting the Sensor to the AC Power Line Connections are made to the AC interface module inside the electronics enclosure AC power connections are made to the AC Interface Board located in the lower center of the electronics enclosure A 3 wire single phase AC source is required consisting of hot neutral and earth ground connections Install a conduit fitting at the location shown in Figure 8 Feed the power cable through the conduit fitting A 3 wire 16 to 18 AWG cable is recommended Crimp fork type terminals to the ends of the wires Connect the three power cable wires to the AC Interface Board terminal blockTB1 pins 1 LINE 2 NEUTRAL and 3 GND Model 6490 I Present Weather Sensor User s Manual 5 OPERATION WITH AN AWOS DATA COLLECTION PLATFORM 5 1 SENSOR INTERFAC
5. scintillations In turn the precipitation rate can be used to determine precipitation accumulation The frequency spectrum of the induced scintillation is analyzed to determine the type of precipitation The Model 6490 I Present Weather Sensor provides accurate precipitation measurements in all weather conditions Designed for rugged unattended operation these sensors have been field proven in adverse environments around the world in locations such as Antarctica Europe the Far East and North America A major advantage of the Model 6490 I Present Weather Sensor is that the measurements are not affected by the buildup of dust dirt or ice on the lenses The weather processing software includes an artificial intelligence and fuss logic based algorithm that makes the baselines self adaptive This corrects the scintillation and forward scattering coefficient changes caused by the gradual obscuration of the light path The need for frequent lens cleaning is eliminated enabling the Model 6490 I Present Weather Sensor to operate for long periods of time completely unattended 1 1 MODELS One 6490 I model is available Model Description 6490 I 115 V 230 V AC Model 6490 I Present Weather Sensor User s Manual 1 2 ACCESSORIES The following accessories and replacement parts are available for the Model 6490 I Present Weather Sensor Part Number Description M488173 01 Present Weather Sensor Standalone Mounting Kit Present W
6. the upper and lower inside surface of lenses The lens surfaces should be slightly warmer to the touch than the ambient temperature 2 Clean Lenses Cleaning the lenses should be done with lint free cloth and cleaning solution Clean the lenses by first spraying the lens cleaner on the lens and then wipe gently to prevent scratching the glass optics In actual practice moderate dust buildup and scratches on the lenses will not have any discernible effect on the instrument 27 Model 6490 1 Present Weather Sensor Users Manual 6 2 TRIANNUAL MAINTENANCE Check the strength of the carrier signal by displaying the present weather status display on the DCP s LCD display screen Press the or keys until the screen is displayed The data fields in bold shown below are the channels of interest W__ P0000S0000VvvvvccXnnnzzzLnnnbbbKnnnbbbHnnnbbbEnnngggTttt 1 Quick Check on Data Fields The following checks are general in nature and should be used as a general indication that the sensor is working properly This test should be performed when there is no precipitation and after the sensor has stabilized for at least 30 minutes Display the present weather data screen on the DCP s LCD display screen using the and keys Present Weather Data PO000S0000 W The present weather field should not contain any data two underscores if there is no precipitation falling S0000 The status fields should all read zero if the 6490 I has
7. 1 M408506 00 B 40 UNISTRUT SS nn ENCLOSURE REF B B ENCLOSURE A ASSY RER ECTION D BERND ASSEMBLY REF section A A Figure 7 Mounting Hardware Details Figure 7 shows the details of securing the mounting hardware These additional steps will help keep the mounting secure and corrosion resistant e Apply anti seize compound to all external threaded connections e Once the installation of the enclosure has been completed apply a light spray of corrosion block to all metallic connectors and threaded fasteners 13 Model 6490 1 Present Weather Sensor Users Manual 4 3 ELECTRICAL CONNECTIONS Figure 8 shows the external connections at the bottom of the enclosure e AC power conduit e Battery backup cable optional e Signal cable from sensor head e Signal cable to Data Collection Platform DCP A user supplied ground wire should also be connected to the ground lug to ground the Model 6490 I Present Weather Sensor to earth potential per local electrical codes AC POWER que OO o O FROM SERIAL CABLE SENSOR HEAD TO DCP Figure 8 External Connections at Enclosure Bottom Route the cable from the sensor head to the bottom of the electronics enclosure Secure the cable to the mast using tie wraps or other straps 1 Route the cable from the sensor head into the electronics enclosure as shown in Figure 8 2 Connect the wires to the connector on the DIN rail shown in Figure 9 according to the wiring diagram in Figu
8. 40 0xa501 0x65c0 0x6480 0xa441 0x6c00 0Oxaccl 0xad81 0x6d40 0xaf01 0x6fc0 0x6e80 0xae4l 0Oxaa01 0x6ac0 0x6b80 0xab41 0x6900 0xa9c1 0xa881 0x6840 0x7800 0xb8c1 0xb981 0x7940 0xbb01 0x7bc0 0x7a80 0xba41 Oxbe01 0x7ec0 0x7f80 0xbf41 0x7d00 0xbdc1 0xbc81 0x7c40 0xb401 0x74c0 0x7580 0xb541 0x7700 0xb7c1 0xb681 0x7640 25 Model 6490 I Present Weather Sensor User s Manual 0x7200 0xb2c1 0xb381 0x7340 0xb101 0x71c0 0x7080 0xb041 0x5000 0x90c1 0x9181 0x5140 0x9301 0x53c0 0x5280 0x9241 0x9601 0x56c0 0x5780 0x9741 0x5500 0x95c1 0x9481 0x5440 0x9c01 0x5cc0 0x5d80 0x9441 0x5f00 0x9fc1 0x9e81 0x5e40 0x5a00 0x9acl 0x9b81 0x5b40 0x9901 0x59c0 0x5880 0x9841 0x8801 0x48c0 0x4980 0x8941 0x4b00 0x8bc1 0x8a81 0x4a40 LD I 0 0x4e00 0x8ec1 0x8f 81 0x4f40 0x8d01 0x4dc0 0x4c80 0x8c4 0x4400 0x84c1 0x8581 0x4540 0x8701 0x47c0 0x4680 0x864 0x8201 0x42c0 0x4380 0x8341 0x4100 0x81c1 0x8081 0x404 cre ival while length cre cre_vals stringt crc amp Oxff crc gt gt 8 amp Oxff return crc end crc16 routine 26 Model 6490 I Present Weather Sensor User s Manual 6 MAINTENANCE AND TROUBLESHOOTING Equipment Required e Clean Cotton Cloth or Lens Tissue e Common Household Glass Cleaner 6 1 MONTHLY MAINTENANCE 1 Check Lens Heaters With a clean finger touch the lenses in front of the disc shaped heaters which are bonded to
9. E 5 1 1 Physical Level The serial signal consists of a three wire RS 485 connection 5 1 2 Link Level Data transfer across the interface is implemented via a serial ASCII encoded half duplex 4800 bps asynchronous transfer link Data transfer in the DCP to sensor direction is limited to a seven character poll PRWX00 lt CR gt Data transfers in the sensor to DCP direction are fixed format ASCII strings starting with an equals sign and terminated with a carriage return lt CR gt 5 1 3 Frame Format The standard output frame format is shown below Details of the data fields are presented in a later section Each of the transmitted characters are eight 8 bit msb bit 7 always 0 no parity ASCII decimal codes 0 to 127 with 1 stop bit The status code and other information is formatted in this way as printable ASCII characters to aid in system debugging and field maintenance The output message from the interface computer in response to the poll consists of the following string of characters Position Contents Description 4 WxxPppppSssss W plus weather code see Section 5 3 1 P plus rain rate in 0 001 inches per hour S plus four digit status code see Section 5 3 2 39 CO AE XnnnLnnnKnnnHnnnTnnn engineering data see Section 5 2 gt sensor crc error counter lt blank gt sensor input msg engineering data see Section 5 2 counter lt blank gt 4 character CRC lt er gt lt If gt crc from position 4
10. H AN AWOS DATA COLLECTION PLATFORM ocan 18 A A A RO re 18 Sl Physical Levels anne an ehe lt 18 5 12 A A ne a bud Mau a Lead bed asad ca 18 SSS Frame A nina Aa a WEA sn 18 3 4 SPTOLOGON 362 sessions ern ann 19 Bie Data OA ES N SEE NE sa 20 Do Data Interpretation brit ainia 22 3 3 1 Weather Codes sais 22 3 322 MAA see ee 23 3 33 Check Sum Caleulation a id 25 6 MAINTENANCE AND TROUBLESHOOTING occoccccnnncccnnnccnonacononacononacononacononacononacononananns 27 6 1 Monthly Maintenance pida ao le 27 6 2 Triannual Maintenance arena 28 Lo PECIFICGA ON Scania 29 8 WARRANTY ercer tidad naaa 31 Model 6490 I Present Weather Sensor User s Manual 1 OVERVIEW nn recipitation types The Model 6490 I Present Weather Sensor optically measures Drizzle precipitation induced scintillation and applies algorithms to determine Rain the precipitation occurrence type and rate automatically The sensor Snow is superior to more traditional sensors and offers reliability and proven performance Precipitation Freezing Rain Freezing Drizzle The Model 6490 I Present Weather Sensor measures precipitation by detecting the optical irregularities known as scintillations induced by particles falling through a beam of partially coherent infrared light in the sample volume The induced scintillations are related to the characteristics to the precipitation and the precipitation rate is determined based on the intensity of these
11. Model 6490 Present Weather Sensor Users Manual Rev A allweatherinc All Weather Inc 1165 National Drive Sacramento CA 95834 USA 800 824 5873 www allweatherinc com Copyright 2012 All Weather Inc All Rights Reserved The information contained herein is proprietary and is provided solely for the purpose of allowing customers to operate and or service All Weather Inc manufactured equipment and is not to be released reproduced or used for any other purpose without written permission of All Weather Inc Throughout this manual trademarked names might be used Rather than put a trademark symbol in every occurrence of a trademarked name we state herein that we are using the names only in an editorial fashion and to the benefit of the trademark owner and with no intention of infringement All Weather Inc and the All Weather Inc logo are trademarks of All Weather Inc Disclaimer The information and specifications described in this manual are subject to change without notice Latest Manual Version For the latest version of this manual see the Product Manuals page under Reference on our web site at www allweatherinc com O aliweatherinc All Weather Inc 1165 National Drive Sacramento CA 95834 Tel 916 928 1000 Fax 916 928 1165 Contact Customer Service e Phone support is available from 8 00am 4 30pm PT Monday through Friday Call 916 928 1000 and ask for Service e O
12. contains the sensor head and cables Also packed in this carton are the sensor head U bolt mounting hardware and electronics enclosure mounting hardware When opening the cartons be careful to avoid spilling the contents CAUTION Exercise care when removing the sensor head from its packing carton The temperature probe at the bottom of the sensor head extends out a short distance and can break easily Report any shortages or shipping damage to All Weather Inc within 3 days CAUTION Do NOT drill holes in any portion of the sensor head or electronics enclosure Doing so will void the warranty and may allow water to enter the enclosure Site Preparation 1 Choose the site using the guidelines in Section 4 2 1 2 Following applicable electrical and building codes install a concrete mounting base mast or tower AC power cable RS 485 signal cable and ground rod Model 6490 I Present Weather Sensor User s Manual 4 2 2 Mount the Sensor Head The sensor must be securely installed and correctly oriented to work properly POLE CAP CONTROL BOX CABLES TO Figure 2 Mounting Present Weather Sensor Head 1 Attach the sensor head using the two U bolts to connect the mounting plate on the sensor head and the mounting bracket with the 4 20 hex locking nuts as shown in Figure 2 To mount the head to a vertical mast or tower section install the U bolts and mounting bracket horizontally To mount to a horizontal towe
13. d so that the receive lens faces north If the orientation can be altered to either side of north to obtain a view with fewer or more distant obstructions it is generally acceptable to alter the orientation up to 30 degrees from north 5 General Recommendations e The sensor must be mounted vertical within 2 degrees so that the line aperture on the in beam lens is horizontal e The sensor is generally oriented with off axis lens facing away from highway or contamination sources to avoid dirt splash directly into the lenses e The sensor should be oriented to avoid direct sunlight shining into the off axis lens SUGGESTION Take a picture at the installation site in each direction north east south and west to record the topography and obstructions for future reference Model 6490 I Present Weather Sensor User s Manual 4 2 MECHANICAL INSTALLATION 4 2 1 Preparation The sensor and site should be readied prior to beginning the installation SITING GUIDELINES Sensor head mounted 2 5 m above ground Rigid mounting pole In beam lens aperture horizontal to 2 degrees No overhanging trees wires or roof lines Distance between sensor and closest obstruction at least 2 times obstruction height As far from road runway and contamination sources as possible The 6490 I Present Weather Sensor is packed in two heavy walled corrugated cartons One carton contains the electronics enclosure and the larger narrow carton
14. de After 5 minutes when reset bit turns off again status codes should be S0000 23 Model 6490 I Present Weather Sensor User s Manual In normal operation excluding the first five minutes after reset or power up the status bytes will be all low 0000 A non zero character in any of the four positions indicates the suspected failure of an FRU The host system should take action to alert maintenance personnel of a possible problem In addition data from the OWI should be disregarded and a missing report issued Note that the sensor does not necessarily stop outputting data when a status bit flags an error condition The table below summarizes the active status bits and the corresponding FRUs and assembly numbers Item Description All Weather Inc P N Sensor Head Assembly M482228 00 Electronics Power Supply M403510 00 The FRUs are available for maintenance and repair of the sensor in the field or depot The sensor head contains no user replaceable parts and can not be repaired except at the factory 24 Model 6490 I Present Weather Sensor User s Manual 5 3 3 Check Sum Calculation The CRC is calculated using a standard crc 16 formula The algorithm is as follows CRC routine used with AWOS remote sensors USE cre crcl6 buffer length initial value where cre is the returned value buffer is the data buffer to compute a crc length is the number of bytes in buffer to process initial_ value is the re
15. e These irregularities are known as scintillation The twinkling of stars is a familiar example of scintillation The precipitation rate is determined by detecting the intensity of the scintillations that are characteristic of precipitation The precipitation type rain snow etc is determined by analyzing the frequency spectrum of the induced scintillation Precipitation is measured using the sensor head in beam optics These components make up the sensor head e Transmitter gt Infrared LED gt Heated transmitter optical lens assembly e Receiver gt Heated receiver optical lens assembly gt Photo detector and preamplifier assembly e Integral Cables gt One external cable for connection to electronics enclosure gt Ground lug for electrical grounding The transmitter portion of the sensor head uses an infrared LED as a light source that is modulated to eliminate interference in the system caused by background light The LED has a very long life time has a relatively low power draw is invisible to the eye and presents no radiation hazard to the user The LED is housed in the smaller of the sensor head boxes A lens is used to collimate the LED s carrier wave modulated light into a slightly diverged beam The transmit and receive lenses are heated by dual self regulating positive temperature coefficient thermistors to a temperature just above the ambient temperature to reduce dew frost and snow on the lenses The larger se
16. ead is completely sealed from water intrusion at the factory Exercise care should to avoid drilling or otherwise puncturing the frame The connecting cable for power and data is found at the bottom of the receiver box along with the temperature probe The 7 6 m 25 ft cable is supplied as part of the sensor to connect the Model 6490 I Present Weather Sensor to the electronics inside the electronics enclosure A Y4 20 threaded hard point and screw are provided on the side of the receiver for electrical grounding A green ground cable is included to connect the sensor to earth ground The terms ground electrical ground and earth ground are defined by the National Electric Code or governing local authority A mounting plate an integral part of the sensor head cross arm is provided to install the head to a user supplied mast Two sets of holes in the mounting plate allow the U bolts supplied with the head to clamp the head to either a vertical or horizontal pipe up to 50 mm in diameter Note The sensor head frame contains no user serviceable parts opening the head will void the warranty Model 6490 I Present Weather Sensor User s Manual 2 1 2 Electronics Enclosure The electronics enclosure contains the processing electronics power supplies and surge protection circuits The electronics enclosure is a fiberglass NEMA 4X type box with a hinged access door One power supply and AC and RS 485 interface modules with su
17. eather Sensor Tandem Mounting Kit M488176 01 to mount Present Weather Sensor on same mast as Model 1190 Data Collection Platform M404806 Serial Sensor Interface Board M442071 10 A 250 V 5x20 mm slow blow fuse F1 AC Interface Board 5 A 250 V 5x20 mm slow blow fuse F2 AC Interface M442070 Board not used Model 6490 I Present Weather Sensor User s Manual 2 SYSTEM DESCRIPTION 2 1 MAJOR COMPONENTS 2 1 1 Sensor Head The 6490 sensor head uses a uses a compact triple aperture optical system to measure precipitation The sensor head frame is an all aluminum welded design The small box TX is the transmitter unit and contains an infrared diode and lens with dual heaters The large box RX contains two independent receiver sections each consisting of a photo diode a lens with dual heaters and preamplifier electronics These two sections operate independently A small panel is attached to the sensor arm to block stray transmitter light from entering the off axis receiver The generated signals are sent to a Digital Signal Processor board located behind the receivers The dual lens heaters prevent dew frost and snow from building up on the lenses and are self regulating devices They are on continuously drawing more current when the outside temperature is cold and less current when the temperature is warm All wiring between the transmit and the receive heads is within the welded head frame The sensor h
18. h raw data field marker High 1 min average raw data Temperature field marker Temperature field Blank This section describes the format of the various fixed fields as they are used in the poll response above 1 The capital letters W P S X L K H and T above serve as place markers for the Weather Precipitation Status Carrier Low Particle High and Temperature data fields to follow These markers are fixed in position and coding They are included within the format to simplify manual interpretation of the sensor output ww is a two byte field indicating present weather The weather codes contained in this field are described in Section 5 3 1 pppp is a four byte field indicating the precipitation rate Zero is formatted as four zeros 0000 The number is a floating point format varying from 0 001 to 9999 The units are inches hour millimeters hour rain rate averaged over a one minute period ssss is a four character field containing ASCII encoded hex value reserved for error and status codes Each character represents a four bit field of binary information The four bit field contains status information of the field replaceable units FRUs The status codes in this field are described in Section 5 3 2 nnn is a three byte ASCII numeric field indicating the corresponding one minute averaged raw data in tens of millivolts Leading unused positions are filled with zeros
19. he same environment as the area around it Ideally the area around the site should be free of buildings trees and other obstructions All Weather Inc 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 from Obstructions 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 tree 20 m high is located alongside the sensor the sensor should be at least 40 m away from the tree This restriction reduces the affects of wind turbulence created by the nearby obstruc tion and makes the precipitation measurement more representative Do not locate the sensor where tree branches or wires will hang over the sensor 2 Separation from Turbulence and Contamination Sources Do not mount the sensor near building exhaust vents strobe lights or sources of smoke or steam Where possible locate the unit 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 m 3 Sensor Height Rigidity Verticality and Orientation The OFCM recommends that the Present Weather Sensor be mounted at a height of 10 ft 3 m This height is
20. ipitation induced frequencies in the range of 1 to 4 kHz that are associated with rain TX Module Contains the voltage controlled oscillator and amplifier to drive the LED in the sensor head Digital Module Contains the A D sample and hold and digital control logic to sample the outputs of the signal processing cards It determines the precipitation type and intensity using algorithms The digital module also performs real time self tests to continually detect faults in the sensor and contains the serial communications port Flash ROM Module Contains an onboard programmable flash ROM and control circuit A new program can be remotely downloaded without any hardware change Ancillary Subassemblies There is one DC to DC converter that provides regulated 5 12 and 12 V DC to the analog and digital electronics The unregulated input voltage nominally 12 V DC is supplied to the lens heaters in the sensor head The 12 V DC input and serial signal line are fully protected from lightning surges by separate modules Model 6490 I Present Weather Sensor User s Manual 4 INSTALLATION 4 1 SITING AND INSTALLATION GUIDELINES The Model 6490 I Present Weather Sensor may be installed almost anywhere outdoors An area free and clear of obstructions and contamination sources will help insure good sensor performance In general the sensor should be located on level or slightly sloping ground where the sensor site will be exposed to t
21. nline support is available by filling out a request at www allweatherinc com customer support html e E mail your support request to support allweatherinc com Model 6490 I Present Weather Sensor Revision A Date 2012 J un 30 Initial release Revision History Summary of Changes User s Manual Model 6490 I Present Weather Sensor User s Manual TABLE OF CONTENTS OVERVIEW aaa ios ia ERROR BOOKMARK NOT DEFINED A AAA a A REINA 1 Hee INCE CSS OTT OS NAS A een 2 2 SYSTEM DESCRIPTION nennen 3 A AA asien 3 DA E E ETE a LEET AE A O RT A TREN 3 2 12 Electronics PROS sionen a ai a a a a aet aai kisas 4 E AAA een 4 3 THEORY OF OPERATION sic isis ince inne 5 Sa a IR PA TE A A Sie ek Se A Siete 5 3 2 Digital Signal Processing DSP Algorithn 2 2 82 na 6 3 21 DSP Algorithm Modules uses 6 A INSTALLATION a tocas 7 4 1 Siting and Installation Guidelines oononnonononoccnocononoonnoonoonncn nooo nonononnnno nono noo n noo nono nonn ron nnnnnnnnno T 4 2 Mechanical sta lO A SS AA A 9 4 2 NO 9 42 2 Mount the Sensor Hed Erin 10 4 2 3 Install the Electronics Enel sure 2 2u 22H aka an na an an 12 4 3 Electrical Connections a A el a A NO 14 4 3 1 RS 485 Connections to the AWOS Data Collection Platform 0 17 4 3 2 Connecting the Sensor to the AC Power Line ooooocnncccnoccconoconcconononnnonnonono cono conn ccoo ncnos 17 5 OPERATION WIT
22. nsor head rectangular box houses the in beam receive optics for present weather sensing and associated photodiode and preamplifier electronics The in beam light passes through a horizontal line aperture to increase the precipitation detection sensitivity to particles falling vertically Signals from the sensor head are carried in a cable to the electronics enclosure Model 6490 1 Present Weather Sensor Users Manual 3 2 DIGITAL SIGNAL PROCESSING DSP ALGORITHM The electronics supporting the 6490 I are integrated inside the sensor head This section describes the modules that make up the functionality for the DSP algorithm The Present Weather Sensor digital signal processor contains several components for power distribution analog signal processing and digital processing 3 2 1 DSP Algorithm Modules AGC Module Automatically adjusts the signal level received from the sensor front end and demodulates the precipitation induced modulation signal from the carrier frequency SP1 Channel Contains two elements the carrier X channel and the low L channel The carrier channel is used to diagnose the carrier signal strength The low channel detects precipitation induced frequencies in the range of 25 to 250 Hz that are associated with snow SP2 Channel Contains two elements the particle counting K channel and the high H channel The particle channel detects the occurrence of falling precipitation The high channel detects prec
23. r section or boom arm install them vertically using the same holes Note that the metallurgy of the stainless U bolts will cause the nuts to seize to the U bolts and twist them off Lubricate the threads with anti seize compound before assembling Do not tighten the nuts completely until the sensor head is installed on the mast or tower and is oriented on the north south axis as shown in Figure 3 10 Model 6490 I Present Weather Sensor User s Manual 2 Rotate the sensor head until the receive lens is facing north MN i L Figure 3 Sensor Head Orientation When mounting the sensor head on a tower choose the tower leg that gives the larger head an unobstructed view to the North without rotating the head assembly into the tower The head assembly should be completely outside the tower as much as possible 3 Tighten the U bolt nuts when the orientation is correct Do not overtighten such that the mounting plate is bent 4 Route the cables along the mast or tower to the electronics enclosure and secure them to the mast or tower every meter using tie wraps or other straps 5 Connect the ground cable to a ground rod TIE WRAP AS NEEDED MOUNTING POLE GREEN GROUND CABLE concrete FOOTER USER SUPPLIED GROUND ROD Figure 4 Installation of Ground Cable 11 Model 6490 I Present Weather Sensor User s Manual 4 2 3 Install the Electronics Enclosure Two mounting kit options are available
24. re 10 14 Model 6490 I Present Weather Sensor User s Manual Figure 9 shows the layout of the various electronics subassemblies inside the electronics enclosure SERIAL SENSOR INTERFACE EMI FILTER D SENSOR HEAD Figure 9 Model 6490 1 Present Weather Sensor Subassemblies Inside Enclosure 15 Model 6490 I Present Weather Sensor User s Manual Figure 10 summarizes all the signal and power wiring for the Model 6490 I Present Weather Sensor Sensor Interface Processor Board ne Function Color 4 RS 485 GREEN 5 RS 485 BROWN 6 GROUND BLACK 7 DC RED AC le Function Color 1 HOT BLACK NEUTRAL WHITE GROUND GREEN CONDUIT FITTING M404802 1 POWER INTERFACE 2 BOARD 1 SENSOR INTERFACE PROCESSOR O RS 232 Tx E DC INPUT DC AND DC CONNECTIONS REFER TO DC POWER SUPPLY HEADER J2 M438210 POWER SUPPLY Figure 10 Model 6490 I Present Weather Sensor Signal and Power Wiring 16 Model 6490 I Present Weather Sensor User s Manual 4 3 1 RS 485 Connections to the AWOS Data Collection Platform RS 485 connections are made to the Serial Sensor Interface located in the upper right side of the electronics enclosure A 3 wire connection to the AWOS Data Collection Platform DCP is used Before proceeding verify that the 6490 I electrical power is turned OFF 1 4 3 2 If the shielded RS 485 cable is not already connected to the DIN
25. rge protection are mounted to the base plate of the enclosure Figure 9 shows the locations of these components inside the enclosure All of the units in the enclosure are field replaceable The electronics enclosure is mounted with the supplied fastener hardware using the four 4 mounting holes on the enclosure If a 6490 1 is purchased by itself there no mounting hardware is provided Note Exercise care to avoid drilling or otherwise puncturing the electronics enclosure 2 1 3 AC Interface Board Two fuses are located on the AC Interface Board see Figure 1 Though installed fuse F2 is only used for the 6490 I Replace the fuses only with fuses of the same rating as shown below Fl 10 A 250 V 5x20 mm slow blow F2 5 A 250 V 5x20 mm slow blow not used 2 115 230 V F2_5A SELECTION 230 V F1 10 A MAIN ON OFF SWITCH Figure 1 AC Interface Board Note that there is a plastic safety shield over the AC Interface Board The fuse holders protrude through the cover Model 6490 I Present Weather Sensor User s Manual 3 THEORY OF OPERATION 3 1 SENSOR HEAD The sensor head is a self contained unit consisting of electro optical components heaters a digital signal processor and integral cabling to connect with the electronics enclosure The sensor measures precipitation by detecting the optical irregularities induced by particles falling through a beam of partially coherent infrared light in the sample volum
26. st 60 seconds or so after reset or power up of the sensor Note AWOS installations with a Present Weather Sensor will also report fog freezing fog haze and mist This information does not originate with the 6490 I sensor but is derived from inputs from other sensors 22 Model 6490 I Present Weather Sensor User s Manual 5 3 2 Status Codes The status codes are a convenient way for the sensor to report sensor condition and identify faulty subassemblies The status field denoted by s s s s four bytes in the data output format is a four byte field of sensor status bytes The codes can be interpreted as shown in the table below S sss s BYTE 10 11 12 13 14 BIT STATUS BIT STATUS BIT STATUS BIT STATUS 0 OK 0 OK 0 OK 0 OK 1 FRU2 1 FRU1 1 1 2 2 2 2 R 3 3 3 3 E 4 4 4 4 S 5 5 5 5 E 6 6 6 6 R 7 7 7 7 yV 8 8 8 RESET 8 E 9 9 9 9 D A status code of 0 in bytes 11 12 13 or 14 indicates no problem while a number or letter other than 0 indicates one or more FRUs may be defective For instance if byte 11 read 1 then FRU 2 should be checked Example Status codes read S0180 Interpret this code as follows Byte 11 0 OK Byte 12 1 FRU 1 probably bad Byte 13 8 Sensor was reset in past 5 minutes Byte 14 0 OK Solution Wait for 5 minutes to verify that the reset bit turns off The status code will now read S0100 indicating that there may be a problem with FRU 1 Replace FRU 1 Sensor Head and recheck the status co
27. sults of previous cre calculations that will allow the buffer crc to be computed in stages if necessary If this is not necessary then set initial_value to 0 unsigned int crcl6 char string unsigned int length unsigned int ival buffer address to compute a crc number of characters to process initial value of crc aay static unsigned int crc CRC values for crc16 routine ES static unsigned int crc_vals 0x0000 0xc0c1 0xc181 0x0140 0xc301 0x03c0 0x0280 0xc241 0xc601 0x06c0 0x0780 0xc741 0x0500 0xc5c1 0xc481 0x0440 Oxcc01 0x0cc0 0x0d80 0xcd41 0x0f00 0xcfc1 0xce81 0x0e40 0x0a00 0xcacl 0xcb81 0x0b40 0xc901 0x09c0 0x0880 0xc841 0xd801 0x18c0 0x1980 0xd941 0x1b00 0xdbc1 0xda81 0x1a40 0x1e00 0xdec1 0xdf81 0x1f40 0xdd01 0x1dc0 0x1c80 0xdc41 0x1400 0xd4c1 0xd581 0x1540 0xd701 0x17c0 0x1680 0xd641 0xd201 0x12c0 0x1380 0xd341 0x1100 0xd1c1 0xd081 0x1040 0xf001 0x30c0 0x3180 0xf141 0x3300 0xf3c1 0xf281 0x3240 0x3600 0xf6c1 0xf781 0x3740 0xf501 0x35Cc0 0x3480 0xf441 0x3c00 0xfcc1 0xfd81 0x3d40 0xff01 0x3fc0 0x3e80 0xfe41l Oxfa01 0x3ac0 0x3b80 0xfb41 0x3900 0xf9c1 0xf881 0x3840 0x2800 0xe8c1 0xe981 0x2940 0xeb01 0x2bc0 0x2a80 0xea41 0Oxee01 0x2ec0 0x2f80 0xef41 0x2d00 0xedc1 0xec81 0x2c40 0xe401 0x24c0 0x2580 0xe541 0x2700 0xe7c1 0xe681 0x2640 0x2200 0xe2c1 0xe381 0x2340 0xe101 0x21c0 0x2080 0xe041 0xa001 0x60c0 0x6180 0xa141 0x6300 0xa3c1 0xa281 0x6240 0x6600 0xa6c1 0xa781 0x67
28. ting Temperature oe oa Storage Temperature Es See Relative Humidity 0 100 noncondensing Model 6490 I Present Weather Sensor User s Manual Parameter Specification Mechanical Electronics Enclosure NEMA 4X fiberglass Sensor Assembly 1 5 3 8 cm dia mast coupling Mounting Electronics Enclosure Unistrut mounted 11 5 cm H x 26 7 cm W x 89 1 cm D Sensor Assembly 4 5 H x10 6 W x35 1 D Dimensions Electronics 36cmW x41cmH x20 cm D Enclosure 14 W x16 H x8 D Sensor Assembly 4 5 kg 10 Ib Weight Electronics Enclosure LEK EE Shipping Weight 2 boxes 16 kg 35 Ib 30 Model 6490 I Present Weather Sensor User s Manual 8 WARRANTY Any defect in design materials or workmanship which may occur during proper and normal use during a period of 1 year from date of installation or a maximum of 2 years from shipment will be corrected by repair or replacement by All Weather Inc 31 allweatherinc All Weather Inc 1165 National Drive Sacramento CA 95818 Fax 916 928 1165 Phone 916 928 1000 Toll Free 800 824 5873 6490 1 001 Revision A June 2012
29. to mount the electronics enclosure e Standalone Mounting Kit AWI part number M488173 01 e Tandem Mounting Kit to mount Present Weather Sensor on same mast tower location as the Data Collection Platform AWI part number M488176 01 Attach the electronics enclosure to the Unistrut brackets using the hardware supplied with the sensor Figure 5 and Figure 6 show the mounting arrangements for the two mounting options _ 7 2X MOUNTING RAIL 14 M105078 01 _7 4X 250 WASHER FLAT 1009041 00 77 4X 250 WASHER LOCK lt Mooada2 00 4 SCREW 2 250 20 X 1 00 MO12004 00 N TL 2 PIPE CLAMP FOR 2 1 2 PIPE M408473 MAST Figure 5 Standalone Enclosure Mounting 12 Model 6490 I Present Weather Sensor User s Manual ce oa 210 Ss iF 7 y 6490 PRESENT 1190 WEATHER DCP SENSOR A A o o lo o 5 6 III N I SIR gt S id RAD AS Br Figure 6 Tandem Present Weather Sensor and DCP Enclosure Mounting 8X SCR 1 4 20 X 1 55 M012004 00 A 8X WASHER LOCK 1 4 20 58 gt TOWER LEG REF A 2X 40 UNISTRUT SS M009032 00 i 8X WASHER FLAT 14 20 88 40 UNISTRUT SS a REF A 4X 1 UNISTRUTCLAMP SS M009041 00 M408149 01 Y Q O m bh gt L i A TOWER LEG HARDWARE INCLUDED WITH 8X NUT UNISTRUT 1 4 20 8S REF CLAMP M408148 0
30. up to but not including the crc itself 18 Model 6490 I Present Weather Sensor User s Manual 5 1 4 Protocol In order to keep the interface design effective and simple the protocol does not support unsolicited messages to the DCP In other words the only time the sensor is allowed to transmit a message to the DCP via this link is in direct response to a poll transmission from the DCP which requires the return ofthe standard data reply string Note that the sensor is sampling data continually every 5 seconds and processing the precipitation algorithm once a minute typical In most cases the DCP s response time to a poll will begin within 100 ms after receiving the poll Requesting data from the sensor more than once per minute will result in identical data transmittals being sent within the one minute period 19 Model 6490 I Present Weather Sensor User s Manual 5 2 DATA FORMAT The raw weather information from the sensor head is encoded in the reply message as follows Section 5 3 provides the processed data that are provided to the DCP by the Present Weather Sensor Description Start of transmission Weather type marker Present weather field Precipitation rate marker Precipitation rate field Status field marker Status field Blank Carrier raw data field marker Carrier 1 min average raw data Low raw data field marker Low 1 min average raw data Particle raw data field marker Particle 1 min average raw data Hig
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