User`s Manual Model 6490 Present Weather Sensor
Contents
1. 5 2 cator afe ie rer Me Lu Scu 21 9 23 523 1 SW Cather E18 E E E RN HIR EN 23 9 927 s Status COUES ce esos uer ep 24 5 3 3 Check Sum Caleulation i etr ener et e e eee aue tone ee E 26 Model 6490 Present Weather Sensor User s Manual 6 MAINTENANCE 4 TROUBLESHOOTING seseeene em Ime emen nrn nnn tre rrr rentrer rias 28 5 1 Monthly du De Pew M EO AV DUIS PALA Ue ea 28 6 2 Triann al Maintenance a RR aquse 28 6 3 Calibration Carrier Level eese esee eee teet tette titt a 29 7a SPEGCGIFRIGATIONS ux tnt tt ties x rN ir A Mr Ap E f 31 8 P rini 12055255 2 222 EU rer ver TU TNT NUNCA 33 Model 6490 Present Weather Sensor User s Manual 1 OVERVIEW Precipitation types The Model 6490 Present Weather Sensor optically measures Drizzle precipitation induced scintillation and applies algorithms to determine the precipitation occurrence type and rate automatically The sensor Snow is superior to more traditional sensors and offers reliability and Precipitation proven performance Freezing Rain The Model 6490 Present Weather Sensor measures precipitation by Freezing Drizzl2. PT Monday through Friday Call 916 928 1000 and ask for Service e Online 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 Present Weather Sensor User s Manual Revision E Date 2011 Oct 31 Revision History Summary of Changes Removed references to OEM part numbers replaced installation drawing with diagrams in the Installation chapter and better explained options and wiring details Model 6490 Present Weather Sensor User s Manual TABLE OF CONTENTS Tc VER MIE VV ches 2221 81224 2 rA c bed be Ea s E eae ard e dS nd 1 12 1 Models 1 ad Eo EM RM dpt hl A Cone toca 2 2 5 01 DESGRIE TION Zasshi s 3 2 1 Major Gomi ponents obsessi tva on wei detur cts dads deudas dU Pet Ua Iu 3 2 1 3b 2 Sensor esc tL 3 2 1 2 Electronics Enclosure eere reve tree ree D e dea aevi eve evt 4 2 053 Interface Bodtd sion noi dep ia iet d teet 4 S THEORY OF OPEBATIODN ee oce cerco eo pte doces te ds Cape oe edo ereptus e ord lc een 5 Sal Sensor Hedd cota Ema en forse fe c pna 5 3 2 ONIONS e DIEGO c Lo MMC EE 6 3 2
3. field should not contain any data two underscores if there is no precipitation falling 28 Model 6490 Present Weather Sensor User s Manual SOOOO The status fields should all read zero if the OWI has 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 4 3 2 for an interpretation of the possible problem Present Weather Stat XnnnLnnnKnnnH nnnTnnn Display the Present Weather Status display on the LCD display and verify the following Lnnn The one minute low channel reading will generally ready in the range of 30 to 50 Knnn The one minute particle channel reading will generally read in the range of 0 to 150 Hnnn The one minute high channel reading will generally read in the range of 40 to 120 Tnnn Temperature should be representative of the ambient temperature 5 degrees The temperature probe is connected thermally to the electronics enclosure so it generally reads warmer than the ambient temperature because of internal heating of the enclosure 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 6 3 CALIBRATION CARRIER LEVE
4. 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 tree20 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 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 When installing on
5. 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 M482105 Transmit Modulator TXM Card M406053 Automatic Gain Control AGC Card M406054 Signal Processor 1 SP1 Card M406055 Signal Processor 2 SP2 Card M406056 Microprocessor MPU Card M406057 Electronics Power Supply M438150 n a Heater Power Supply M438151 PCB Sensor Interface M404806 Present Weather Firmware EPROM M469053 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 25 Model 6490 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 crc crcl6 buffer length initial value where crc is the returned value buffer is the data buffer to compute a crc length is the number of byt
6. 1 Controller eene eterne seen enne 6 A INSTALLATIONS cec o it ace elt idee IC teet 7 4 1 Siting and Installation Guide nes ttes 7 4 2 Mechanical re Ute ee FO Ebo dad 9 4 21 SPIODACALIOIE a 9 42 2 Mountthe Serisor Head et eter eese fever Te vester gest 10 4 2 3 Install the Electronics Enclosure 12 4 3 Electrical Contectiofls isse de bois otro pero CUR Praese ele 14 431 RS 485 Connections to AWOS Data Collection Platform 17 4 3 2 Connecting the Sensor to the AC Power 2 eet 17 4 3 3 Optional Backup Battery 18 4 3 4 Model 6490 A Heaters sit tenir ie e e n dO e eere PER 18 5 OPERATION WITH AWOS DATA COLLECTION PLATFORM 19 Sensor Interfaces 2 Uns cst coe oe iren nl oce cere e eee Carsten foi 19 Dub Physical Level snoscnsioteqetssto esr edet detentus andata desee d Doo M D sedes 19 925 Tank xeu vethusito nunt v temm 19 5 1 3 ei obere see ii ted pe eder 19 Protocol ce St reet tee due EPI ERE EE 20
7. 6180 0xa141 0x6300 0xa3c1 0xa281 0x6240 0x6600 0xa6c1 0xa781 0x6740 0xa501 0x65c0 0x6480 0xa441 0x6c00 0xacc1 0xad81 0x6d40 0xaf01 0x6fc0 0x6e80 0xae41 0xaa01 0x6ac0 0x6580 0xab41 0x6900 0xa9c1 0xa881 0x6840 0x7800 0xb8c1 0x5981 0x7940 0xbb01 0x75c0 0x7a80 0xba41 0xbe01 0x7ec0 0x7 80 0xbf41 0x7d00 0xbdc1 0xbc81 0x7c40 Oxb401 0x74c0 0x7580 0xb541 0x7700 0xb7c1 0xb681 0x7640 26 Model 6490 Present Weather Sensor User s Manual 0x7200 0xb2c1 0x5381 0x7340 0xb101 0x71c0 0x7080 0xb041 0x5000 0x90c1 0x9181 0x5140 0x9301 0x53c0 0x5280 0x9241 0x9601 0x56c0 0x5780 0x9741 0x5500 0x95c1 0x9481 0x5440 0x9c01 0x5cc0 0x5d80 0x9d41 0x5 00 0x9 c1 0x9e81 0x5e40 0x5a00 0x9acl 0x9b81 0x5b40 0 9901 0 59 0 0 5880 0 9841 0 8801 0 48 0 0 4980 0 8941 0 4 00 0 8 1 0 8 81 0 4 40 1 1 0 0x4e00 0x8ec1 0x8 81 0x4f 40 0x8d01 0x4dc0 0x4c80 0x8c4 0 4400 0 84 1 0 8581 0 4540 0 8701 0 47 0 0 4680 0 864 0 8201 0 42 0 0 4380 0 8341 0 4100 0 81 1 0 8081 0 404 crc ival while lengtn crc cro vals string crc 8 Oxff cro gt gt 8 amp Oxff return crc end crel6 routine 27 Model 6490 Present Weather Sensor User s Manual 6 MAINTENANCE amp TROUBLESHOOTING Equipment Required e Clean Cotton Cloth or Lens Tissue e Common Household Glass Cleaner 6 1 MONTHLY MAINTENANC
8. E Check Lens Heaters With a clean finger touch the lenses in front of the disc shaped heaters which are bonded to 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 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 carrier raw data field Xnnn should be in the range of 405 420 If it needs to be adjusted go to Section 6 3 The data fields in bold shown below are the channels of interest XnnnLnnnKnnnHnnnTnnn 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 The present weather
9. L The carrier level can be easily adjusted without special test equipment DO NOT PERFORM IN PRECIPITATION FOG FREEZING FOG OR MIST Thoroughly clean both lenses with glass cleaner and a soft cloth before proceeding Clean the lenses by first spraying the lens cleaner on the lens and then wipe gently to prevent scratching the glass optics Procedure 1 Turn power to the Sensor ON and allow 10 minutes before taking a reading of the data string 2 Display the present weather status display on the LCD screen The Carrier raw data field should contain Channel Data Value Tolerance Carrier X405 to 420 Anywhere in range The Carrier raw data field should be in the range of 405 420 If it needs to be adjusted go to Step 3 Keep the electronics enclosure door closed during the calibration process The data fields in Bold shown below are the channels of interest 29 Model 6490 Present Weather Sensor User s Manual 3 Carrier Channel Adjustment Locate SP1 card in enclosure SP1 Adjust post as shown at left to increase or decrease data value LO CW Wait 2 3 minutes Verify Carrier channel is 405 to 420 per data fields Increase shown below Readjust as necessary to reach correct value The carrier adjustment by the pot labeled is read in the data string at the X position HINT A turn of the pot will typically be enough to adjust the carrier 10 15 counts Wait for 2 3 mi
10. Model 6490 Present Weather Sensor User s FAA APPROVAL PENDING Rev E ECP 204 to be submitted NOT FAA APPROVED allweatherinc All Weather Inc 1165 National Drive Sacramento 95834 USA 800 824 5873 www allweatherinc com Copyright O 2011 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 TM symbol in every occurtence 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 tradematks 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 42 alweatherinc 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
11. NTERPRETATION 5 3 4 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 place marker NWS WX Code Description Code NWS WX Code Description Light Drizzle I Light Ice Pellet Moderate Drizzle I Moderate Ice Pellet Heavy Drizzle I Heavy Ice Pellet Light Rain A Light Hail Moderate Rain Moderate Hail Heavy Rain A Heavy Hail Light Precipitation 2 3 No Precipitation Moderate Precipitation Start up code Heavy Precipitation ER Error Condition Light Snow CL Lenses need to be cleaned Moderate Snow only reported when no Heavy Snow precip Freezing Drizzle Freezing Rain The underline character above represents an ASCII underline character The code will be output in this and other data fields during the first 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 sensor but is derived from inputs from other sensors 23 Model 6490 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 sen
12. OCK 1 4 20 88 TOWER LEG REF A 2X 40 UNISTRUT SS M009032 00 8X 20 68 40 UNISTRUT SS n i t REF 4X 1 UNISTRUT CLAMP SS B M009041 00 M408149 01 IS O Cum Hf E TOWER LEG HARDWARE INCLUDED WITH 8X NUT UNISTRUT 1 4 20 58 REF CLAMP MA08149 01 408508 00 B 40 UNISTRUT SS ENCLOSURE REF B B ENCLOSURE A ECTION ASSEMBLY REF section A A Figure 6 Mounting Hardware Details Figure 6 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 Present Weather Sensor User s Manual 4 3 ELECTRICAL CONNECTIONS Figure 7 shows the external connections at the bottom of the enclosure e AC power conduit e Battery backup cable optional e Signal cables from sensor head e A ground lug A user supplied ground wire should also be connected to the ground lug to ground the Model 6490 Present Weather Sensor to earth potential per local electrical codes FROM SENSOR HEAD AC POWER CONDUIT BATTERY BACKUP CABLE TO DCP optional SERIAL CABLE GROUND TEMPERATURE TO DCP LUG PROBE Figure 7 External Connections at Enclosure Bottom Note that the enclo
13. SOR M492557 CABLE M404802 CONDUIT 1 POWER INTERFACE FITTING BOARD le o o o o o o Figure 9 Present Weather Sensor Signal and Power Wiring 16 Model 6490 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 lower right side of the electronics enclosure A 3 wire connection to the AWOS Data Collection Platform DCP is required Before proceeding verify that the 6490 electrical power is turned OFF 1 If the RS 485 cable is not already connected to the Serial Interface Processor connect the WHITE RS 485 signal cable to pin 4 connect the BLACK RS 485 signal cable to pin 5 and connect the RED GND cable to pin 6 of the Serial Interface Processor s terminal block 2 Feed the free end of the three conductor RS 485 cable through the serial cable gland shown in Figure 7 3 Strip and tin the ends of the wires 4 Route the cable through a cable gland on the DCP and connect the three wires inside the DCP to TB4 pins 1 RS 485 2 5 485 and 7 GND 5 Ensure that none of the wires are stressed then hand tighten the gland seals on the DCP enclosure and on the Model 6490 Present Weather Sensor enclosure 4 3 2 Connecting the Sensor to the AC Power Line Connections are made to the AC surge protection module inside the electronics enclosure AC power connections are made to
14. alone Mounting Kit Present Weather Sensor Tandem Mounting Kit M488176 01 to mount Present Weather Sensor on same mast as Model 1190 Data Collection Platform M488181 Optional Heater Kit already included with Model 6490 A M404806 Serial Sensor Interface Board 442071 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 Board used with 230 V setting An optional rechargeable backup battery kit AWI part number 11903 housed in the nearby Model 1190 Data Collection Platform is available to power the Model 6490 Present Weather Sensor and the Model 1190 Data Collection Platform in the event of an AC power failure Model 6490 Present Weather Sensor User s Manual 2 SYSTEM DESCRIPTION 2 1 MAJOR COMPONENTS 2 1 1 Sensor Head The 6490 sensor head uses a compact 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 IRED diode and lens with dual heaters The large box RX contains a receiver assembly consisting of a photo diode lens with dual heaters and preamplifier electronics The dual lens heaters prevent dew frost and snow from building up on the lenses and are self regulating devices They are continuously drawing more current when the outside temperature 15 cold and less current when the temperature is warm All wiring between the tran
15. ary algorithms The microprocessor also performs real time self tests to detect faults in the sensor on an ongoing basis and contains an RS 232 communication port Ancillary Subassemblies There are two power supplies a 12 V DC power supply and a DC DC converter that provides regulated 5 12 and 12 V DC to the analog and digital electronics The lens heaters in the sensor head use 12 V DC from the DC DC converter The AC input and RS 485 signal lines are fully protected from the lightning surges by surge suppres sion circuits Surge suppression is also used at the termination points for the user AC and RS 485 connections A precision thermistor type temperature probe is attached to the bottom of the enclosure It is used for automatic temperature compensation in the algorithm The temperature measured by the probe is not meant for meteorological reporting Model 6490 Present Weather Sensor User s Manual 4 INSTALLATION 4 1 SITING AND INSTALLATION GUIDELINES The Model 6490 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 the 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
16. ather 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 CABLES TO CONTROL BOX 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 14 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 tower 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 Present Weather Sensor User s Manual 2 Rotate the sensor head until the receive lens is facing north NN 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 mou
17. ation the precipitation rate is determined By analyzing the frequency spectrum of the induced scintillation the precipitation type rain snow etc is determined Precipitation is measured using the sensor head in beam optics These components make up the sensor head e Transmitter Infrared LED Heated transmitter optical lens assembly e Receiver gt Heated receiver optical lens assembly gt Photo detector and preamplifier assembly e Integral Cables gt 2 external cables for connection to electronics enclosure 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 sensor 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 apertu
18. cal 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 20 Model 6490 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 High 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 S X L and 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 outp
19. ds 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 NN XnnnLnnnKnnnHnnnTnnn engineering data see Section 5 2 bln _ _ ___ __ _ O sensor crc error counter blank sensor input msg engineering data see Section 5 2 counter lt blank gt 4 character CRC lt cr gt lt lf gt crc from position 4 up to but not including the crc itself 19 Model 6490 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 of the standard data reply string Note that the sensor is sampling data continually every 5 seconds and processing the precipitation algorithm once a minute typi
20. e 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 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 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 1 1 MODELS Three 6490 models are available Model Description 6490 standard for North America 115 V 230 V AC 6490 A with heater for AWSS installations 115 V AC 6490 1 standard for outside North America 115 V 230 V AC The Model 6490 I Present Weather Sensor is described in detail in the Model 6490 I Present Weather Sensor User s Manual Model 6490 Present Weather Sensor User s Manual 1 2 ACCESSORIES The following accessories and replacement parts are available for the Model 6490 Present Weather Sensor Part Number Description M488173 01 Present Weather Sensor Stand
21. e 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 Present Weather Sensor is packed in two heavy walled corrugated cartons One carton contains the electronics enclosure and the larger narrow carton 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 electronics enclosure from its packing carton The temperature probe at the bottom of the enclosure 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 Present We
22. es in buffer to process initial value is the results of previous crc 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 crcl 6 char string unsigned int length unsigned int ival buffer address to compute a crc number of characters to process initial value of crc mu static unsigned int crc F CRC values for crcl6 routine static unsigned int crc vals 0x0000 0xc0c1 0xc181 0x0140 0xc301 0x03c0 0x0280 0xc241 0xc601 0x06c0 0x0780 0xc741 0x0500 0xc5c1 0xc481 0x0440 Oxcc01 0x0cc0 0x0d880 0xcd41 0x0 00 0xcfc1 0xce81 0x0e40 0x0a00 0xcaci1 0xcb81 0x0040 0xc901 0x09c0 0x0880 0xc841 0xd801 0x18c0 0x1980 0xd941 0x1000 0xdbc1 0xda81 0x1a40 0x1e00 0xdec1 0xdf81 0x1f40 0xdd01 0x1dc0 0x1c80 0xdc41 0 1400 0 44 1 0 581 0 1540 0 701 0 17 0 0 1680 0 4 641 0xd201 0x12c0 0x1380 0xd341 0x1100 0xd1c1 0xd081 0x1040 0xf001 0x30c0 0x3180 0xf141 0x3300 0xf3c1 0xf 281 0x3240 0x3600 0xf6c1 0xf781 0x3740 0xf501 0x35c0 0x3480 0xf441 0x3c00 0xfcc1 0xfd81 0x3d40 0xf f01 0x3fc0 0x3e80 0xfe41 Oxfa01 0x3ac0 0x3b80 0xfb41 0x3900 0xf9c1 0xf 881 0x3840 0x2800 0xe8c1 0xe981 0x2940 0xeb01 0x2bc0 0x2a80 0xea41 Oxee01 0x2ec0 0x2 80 0xef41 0x2d00 0xedc1 0xec81 0x2c40 0xe401 0x24c0 0x2580 0xe541 0x2700 0xe7c1 0xe681 0x2640 0x2200 0xe2c1 0xe381 0x2340 0xe101 0x21c0 0x2080 0xe041 0xa001 0x60c0 0x
23. ide the DCP to TBI pins 1 WHT and 2 Ensure that none of the wires are stressed then hand tighten the gland seals on the DCP enclosure and on the Model 6490 Present Weather Sensor enclosure Heater Kit The Model 6490 A Present Weather Sensor comes with a built in heater installed on the inside of the enclosure door There is a knob that can be used to adjust the temperature The heater is a factory installed option for other models Figure 10 shows the electrical connections for reference DC POWER M404802 SUPPLY GRN AC INTERFACE WHT BOARD TO SITE AC POWER e 28 488181 HEATER KIT Figure 10 Heater Electrical Connections 18 Model 6490 Present Weather Sensor User s Manual 5 OPERATION WITH AN AWOS DATA COLLECTION PLATFORM 5 1 SENSOR INTERFACE 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 Data transfers in the sensor to DCP direction are fixed format ASCII strings starting with an equals sign and terminated with a carriage return CR 5 1 3 Frame Format The standard output frame format is shown below Details of the data fiel
24. lectronics enclosure is mounted with the supplied fastener hardware using the four 4 mounting tabs on the enclosure 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 needed only for 230 V operation S2 115 230 V 2 5 SELECTION 230 V F1 10A MAIN ON OFF SWITCH Figure 1 AC Interface Board Note that there is a plastic safety shield over the AC Interface Board This shield must be removed to access the fuses for replacement and should be reinstalled once the fuse has been replaced 4 Model 6490 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 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 volume 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 precipit
25. nting 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 11 Model 6490 Present Weather Sensor User s Manual 4 2 3 Install the Electronics Enclosure Two mounting kit options are available 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 4 and Figure 5 show the mounting arrangements for the two mounting options _ 7 2X MOUNTING RAIL 14 M105078 01 22 4X 250 WASHER FLAT 27 M008041 00 AX 250 WASHER LOCK 70 MOD9032 00 177 4X SCREW 25020X100 012004 00 SM SL 2x PIPE CLAMP FOR 2 4 2 PIPE M408473 MAST Figure 4 Standalone Enclosure Mounting 12 Model 6490 Present Weather Sensor User s Manual 6490 PRESENT WEATHER SENSOR NASA SANA A ANS AN ANN 7 OUS Figure 5 Tandem Present Weather Sensor and DCP Enclosure Mounting SCR 1 4 20 X 17 85 012004 00 8X WASHER L
26. nutes to see if the adjustment is sufficient before adjusting again 30 Model 6490 Present Weather Sensor 7 SPECIFICATIONS Parameter User s Manual Specification 6490 A Present Weather Codes Reported 250 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 570 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 1096 Data Update Rate Once per minute Serial Output RS 485 Output Format ASCII characters Baud Rate 4800 bps Serial Port Parameter Setting Power Requirements Supply Voltage 8 N 1 8 data bits no parity 1 stop bit 115 230 V AC 115 V AC 115 230 V AC 50 60 Hz 50 60 Hz 50 60 Hz 50 50 VA 50 V A Transient Protection Environmental AC power and RS 485 signal lines fully protected Operating Temperature e Storage Temperature i pen Relative Humidity 0 10096 noncondensing 3l Model 6490 Present Weather Sensor Parameter Specification User s Manual 6490 A Mechanical NEMA 4X NEMA 4X electro polished NEMA 4X Controller Assembly Enclosure fiberglass 304 stainless fiberglass steel Sensor Assembly 2 5 6 35 cm dia mast Mounting Contr
27. oller Assembly Unistrut mounted 11 5 cmH x23 0 cm W x 73 0 cm D Sensor Assembly 4 5 H x9 1 W 28 75 Dimensions 36cmW x41cmH 41emW x51cmH 36cmW x4lcmH Controller x20 x24 cmD x20 Assembly 14 W 16 16 W x20 H 14 W x16 H x 8 D x 9 25 D 8 D Sensor Assembly 4 kg 8 8 Ib 4 kg 8 8 Ib 4 kg 8 8 Ib Weight Controller Assembly 10 kg 22 Ib 12 kg 27 Ib 10 kg 22 Ib Shipping Weight 2 boxes 16 kg 35 Ib 18 kg 40 Ib 16 kg 35 Ib 32 Model 6490 Present Weather Sensor User s Manual 8 WARRANTY This equipment has been manufactured and will perform in accordance with requirements of FAA Advisory Circular 150 5220 16B 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 AII Weather Inc 33 allweatherinc All Weather Inc 1165 National Drive Sacramento CA 95818 Fax 916 928 1165 Phone 916 928 1000 Toll Free 800 824 5873 6490 001 Revision E September 2011
28. re to increase the precipitation detection sensitivity to particles falling vertically Signals from the sensor head are carried in two separate cables to the electronics enclosure Model 6490 Present Weather Sensor User s Manual 3 2 CONTROLLER The Present Weather Sensor controller contains several components for power distribution analog signal processing and digital processing 3 2 1 Controller Subassemblies AGC Card Automatically adjusts the signal level received from the sensor head and demodulates the precipitation induced modulation signal from the carrier frequency SP1 Contains two elements the carrier channel and the low 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 which are associated with snow SP2 Contains two elements the particle counting channel and the high channel The particle channel detects the occurrence of falling precipitation The high channel detects precipitation induced frequencies in the range of 1 to 4 kHz which are associated with rain TXM Card Contains the voltage controlled oscillator which is amplified to drive the LED in the sensor head Microprocessor Card Contains the A D converter sample and hold and microprocessor control logic to sample the outputs of the signal processing cards Determines the precipitation type and precipitation intensity using propriet
29. smit and the receive heads is within the welded head frame The sensor head is completely sealed from water intrusion at the factory Exercise care should to avoid drilling or otherwise puncturing the frame Two integral cables with a length of 5 m are supplied as part of the sensor head frame a transmit cable P5 and an in beam receive cable P4 A green ground cable is provided to electrically ground the sensor head to the electronics enclosure 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 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 or stainless steel NEMA 4X type box with a hinged access door Two power supplies a controller card cage with five printed circuit boards and AC and RS 485 interface modules with surge protection are mounted to the base plate of the enclosure Figure 8 shows the locations of these components inside the enclosure All of the units in the enclosure are field replaceable The e
30. sor status bytes The codes can be interpreted as shown in the table below S s s 8 8 BYTE 10 11 12 13 14 BIT STATUS BIT STATUS BIT STATUS BIT STATUS 0 OK 0 OK 0 OK 0 OK 1 FRU3 1 FRUI 1 1 2 FRU2 2 FRU9 2 2 3 FRU2 3 3 FRU9 1 3 3 I 4 FRU7 4 FRUS 4 4 T 5 FRU7 3 5 FRUS 1 5 5 S 6 7 2 6 FRUS 9 6 6 7 FRU7 2 3 7 FRUS 9 1 7 7 R 8 FRUS 8 FRU4 8 RESET 8 E 9 FRUS 3 9 FRU4 1 9 9 S A FRUS 2 A FRU4 9 A A B 8 2 3 FRU4 9 1 B B R C FRUS 7 C 4 5 C C D FRUS 7 3 D FRU4 5 1 D D E E 8 7 2 E FRU4 5 9 E E D F FRUS 723 FRUA4 5 91 F F A status code of 0 in bytes 11 12 13 or 14 indicates problem while a number or letter other than 0 indicates one or more FRUs may be defective For instance if byte 11 read 9 then both FRU 8 amp FRU 3 should be checked Example Status codes read 50180 Interpret this code as follows Byte11 Z0 OK Byte 1221 FRU 1 probably bad Byte 13 2 8 MPU was reset in past 5 minutes Byte 14 0 OK Model 6490 Present Weather Sensor User s Manual Solution Wait for 5 minutes to verify that the reset bit turns off The status code will now read 50100 indicating that there may be a problem with FRU 1 Replace FRU 1 Sensor Head and recheck the status code After 5 minutes when reset bit turns off again status codes should be 50000 In normal operation excluding the first five minutes after reset or power up the status bytes will be all low
31. sure bottom layout for the Model 6490 A enclosure is slightly different Finish routing the cables from the sensor head to the bottom of the electronics enclosure Secure any loose cables to the mast or tower pole using tie wraps or other straps 1 Connect the sensor head cables labeled P4 and P5 to the electronics enclosure connectors shown in Figure 7 The connectors are keyed so they can only plug into the correct receptacle P4 connects the receiver and P5 connects the transmitter 2 Connect the sensor head green wire to the ground lug on the bottom of the enclosure 14 Model 6490 Present Weather Sensor User s Manual Figure 8 shows the layout of the various electronics subassemblies inside the electronics enclosure PRESENT WEATHER SENSOR CONTROLLER 14 gt 2 INTERFACE AC INTERFACE DC POWER BOARD SUPPLY Figure 8 Present Weather Sensor Controller Subassemblies Inside Enclosure 15 Model 6490 Present Weather Sensor User s Manual Figure 9 summarizes all the signal and power wiring for the model 6490 Present Weather Sensor Sensor 1 Color DCP in Pin 4 RS 485 WHITE 1 5 RS 485 BLACK 2 6 GROUND RED 7 AC 1 Function Color in 1 HOT BLACK 2 NEUTRAL WHITE 3 GROUND GREEN SENSOR INTERFACE PROCESSOR 6490 o Rs 232 Tx PRESENT WEATHER SEN
32. 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 Before proceeding verify that the unit you are installing is configured for the same voltage available at the site Refer to the voltage selection switch on the AC Interface Board 1 Feed the power cable through the conduit fitting shown in Figure 7 A 3 wire 16 to 18 AWG cable is recommended 2 Crimp fork type terminals to the ends of the wires 3 Connect the three power cable wires to the AC Interface Board terminal blockTB1 pins 1 LINE 2 NEUTRAL and 3 GND Model 6490 Present Weather Sensor User s Manual 4 3 3 Optional Backup Battery Connections An optional rechargeable backup battery kit housed in the nearby Model 1190 Data Collection Platform is available to power the Model 6490 Present Weather Sensor and the Model 1190 Data Collection Platform in the event of an AC power failure l 4 3 4 The backup battery cable AWI part number M491561 is already connected to the terminal block on the DC DC converter inside the LAN Optional Present Weather sensor enclosure The remaining cable is looped and Backup stored inside the enclosure Battery Connection Feed the free end of the backup battery cable through the serial cable gland shown in Figure 7 Route the cable through a cable gland on the DCP and connect the two wires ins
33. the Model 8518 A Foldover Tower mount the Present Weather Sensor to the hinged side of the tower For AWOS installations All Weather Inc recommends that the sensor head be mounted 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 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 The sensor head must be mounted vertical within 2 degrees so that the line aperture on the in beam lens is horizontal Model 6490 Present Weather Sensor User s Manual 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 head 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 Model 6490 Present Weather Sensor User s Manual 4 2 MECHANICAL INSTALLATION 4 2 1 Preparation The sensor and sit
34. ut 2 ww is a two byte field indicating present weather The weather codes contained in this field are described in Section 5 3 1 3 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 4 888818 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 5 nnnisa three byte ASCII numeric field indicating the corresponding one minute averaged raw data in tens of millivolts Leading unused positions are filled with zeros Valid values are 99 to 999 Overflows and underflows are represented as 999 and 99 respectively 21 Model 6490 Present Weather Sensor User s Manual 6 tttis 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 22 Model 6490 Present Weather Sensor User s Manual 5 3 DATA I
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