Vaisala PWD22, User Manual

Page 1: ...Present Weather Detector PWD22 USER S GUIDE M210543EN B January 2004...

Page 2: ...echanical including photocopying nor may its contents be communicated to a third party without prior written permission of the copyright holder The contents are subject to change without prior notice...

Page 3: ...1 CHAPTER 2 PRODUCT OVERVIEW 13 Introduction to Vaisala Present Weather Detector PWD22 13 Hardware Structure 14 Sensing Element in PWD22 14 PWT11 Transmitter 14 PWC22 Controller Receiver 15 Vaisala RA...

Page 4: ...Memory Tests 33 Signal Monitoring 34 Hardware Monitoring 34 Monitoring Contamination 34 CHAPTER 4 INSTALLATION 37 Selecting Location 37 Grounding and Lightning Protection 39 Equipment Grounding 39 In...

Page 5: ...ssage 3 60 Message 4 60 Messages 5 and 6 60 Message 7 61 Automatic Message Sending 62 Message Polling 62 Precipitation Sums 64 List of Commands 65 PWD22 Command Set 65 HELP 65 MES 66 AMES 66 Weather R...

Page 6: ...OOTING 99 Common Problems 99 Message Indicating Warning or Alarm 99 Message Missing 100 Message Exists but Visibility Value Does Not 101 Visibility Value is Continuously Too Good 101 Visibility Consta...

Page 7: ...6 Relay Connection PWD22 Supplies 52 Figure 17 Relay Connection External Relay Supply 53 Figure 18 Illustration of Contents of Messages 0 1 and 2 58 Figure 19 Analog Current Output Connection 77 Figur...

Page 8: ...Table 21 PWD22 Electrical Specifications 108 Table 22 Optical Specifications of the Light Transmitter 108 Table 23 Optical Specifications of the Light Receiver 109 Table 24 Visibility Measurement Spec...

Page 9: ...apter 1 General Information provides general notes for the product Chapter 2 Product Overview introduces Vaisala Present Weather Detector PWD22 features advantages and the product nomenclature Chapter...

Page 10: ...the manual Version Information Table 1 Manual Revisions Manual Code Description M210543EN A This manual Related Manuals Table 2 Related Manuals Manual Code Manual Name M210542EN A Vaisala Present Weat...

Page 11: ...ow instructions carefully at this point the product could be damaged or important data could be lost NOTE Note highlights important information on using the product Product Related Safety Precautions...

Page 12: ...ion in 47 CFR 15 838 has specified that the following notice must be brought to the attention of users of this kind of a product in the USA Federal communications commission radio frequency interferen...

Page 13: ...cord When neither of the above is possible touch a conductive part of the equipment chassis with your other hand before touching the boards Always hold the boards by the edges and avoid touching the c...

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Page 15: ...is equipped with a background luminance sensor it can also measure ambient light PWD22 suitable for automatic weather station applications especially for low power requirement installations Table 3 Mo...

Page 16: ...nto a crossarm using the mounting clamps 0308 002 Figure 1 PWD22 Present Weather Detector The following numbers refer to Figure 1 above 1 Transmitter 2 Controller Receiver 3 PWR211 Vaisala RAINCAP Rai...

Page 17: ...by an insulating glass coating The presence of water changes the capacitance of the plate The capacitance is measured by the integrated electronics The integrated heating resistors keep the elements d...

Page 18: ..._______________________________________________________ 16____________________________________________________________________M210543EN B data processing is done by the embedded software The main unit...

Page 19: ...t is either a digital serial interface or an analog current signal The digital serial interface can be configured into two different operating modes the sensor can be set to send a data message automa...

Page 20: ...nd photo diode circuit board for PWD22 PWR211 RAINCAP Double Plate Rain Sensor A capacitive detector to sense water droplets and or moisture Two plate in a 90 degree angle towards each other Table 5 N...

Page 21: ...ct on the MOR must be handled separately Usually these particles are precipitation droplets The optical arrangement of PWD22 is such that individual droplets can be detected from rapid signal changes...

Page 22: ...rticles to be measured even at relatively heavy precipitation intensities The signal levels from even the smallest precipitation droplets can also be detected Transmitter Unit PWT11 The transmitter un...

Page 23: ...oes it saturate the preamplifier The AMBL signal proportional to the ambient light is lead to the CPU for monitoring Additional Measurements PWD22 includes RAINCAP for estimating the water content of...

Page 24: ...ven with no precipitation In PWD22 this is used as an estimated humidity measurement The estimated humidity is used to separate between dust and mist As PWD22 can detect the beginning of precipitation...

Page 25: ...the positive scaling factor for the luminance value See the example below BLSC 1 0 The response is the following BL SCALE 1 000 Background luminance is reported in a range of 4 20000 cd m2 with the ab...

Page 26: ...temperature is measured once a minute using a high resolution A D converter The sensor crossarm temperature TS is used to select the default precipitation type The sensor is not shielded from solar ra...

Page 27: ...converts frequency into visibility MOR The transfer function has been defined with an accurate transmissometer Vaisala MITRAS as a reference The instantaneous 15 s visibility values are averaged to ge...

Page 28: ...cipitation the shape of particles varies but they are proportional to the average volume of the particles Optical precipitation intensity value is calculated from the signal change distribution data a...

Page 29: ...intensities The snow sum is accumulated from the optical intensity when snow is detected The snow sum is only a coarse estimate of the thickness of snow In a shorter period the accumulated snow value...

Page 30: ...practical definition of rain or drizzle freezing on surfaces not on detecting supercooled water Rain If the maximum droplet size is bigger than the Drizzle limit the precipitation type is rain Light...

Page 31: ...ity ratio is between 1 and Snow limit The intensity is determined by estimating the water equivalent intensity and using the rain intensity limits Ice Pellets Ice pellets is reported if the sensor cro...

Page 32: ...eduction in visibility is caused by moisture in the air HAZE SMOKE DUST or SAND 05 Lower than 1 km No precipitation Reduction in visibility is caused by moisture in the air WMO has not clearly defined...

Page 33: ...le 7 WMO METAR Code Limits Code 10 minute Visibility Average None Higher than 5 km MIST BR Higher than or equal to 1 km but lower than or equal to 5 km FOG FG Lower than 1 km Weather Classes The weath...

Page 34: ...ue in other words the highest SYNOP code number first This table is then analyzed from top down by adding the counts together until a minimum sum is obtained The code number associated with the last a...

Page 35: ...ng measurements are displayed in volts or hertz depending on their origin Program operation is monitored by the watchdog circuitry If the circuit is not triggered in about two seconds it will perform...

Page 36: ...in a batch PWD22 checks that the frequencies are not zero and signal sample count is bigger than the offset sample count Errors in signal or offset are fatal and data is set to Offset drift is monito...

Page 37: ...easured values are used only for warnings and alarms No compensation for the visibility signal is calculated Transmitter backscatter is measured by an analog circuit using the transmitter LED as a lig...

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Page 39: ...for PWD22 has a minimum clearance of 100 m from all large buildings and other constructions that generate heat and obstruct precipitation droplets Avoid the shade of trees because the trees may cause...

Page 40: ...m passing vehicles Dirty lenses will cause the sensor to report too high visibility values Excessive contamination is automatically detected by the sensor In the road environment the receiver should f...

Page 41: ...cable can also be cast inside the concrete base The length of the grounding rod depends on the local groundwater level The lower end of the grounding rod should touch moist soil continuously The qual...

Page 42: ...the case more than five centimeters Unpacking Procedure 1 Read the packing list supplied within the delivery documents Then compare the packing list against the purchase order to make sure that the sh...

Page 43: ...rial line automatically The interval and message type can be changed by the user the AMES command In addition the baud rate of the serial line can be changed to other value and the data frame can be s...

Page 44: ...0 Commands for Displaying and Changing Parameters Operation Command Parameter listing WPAR Parameter setting WSET Local practice may require changes especially in the precipitation intensity limits mo...

Page 45: ...___________________________________________43 0401 182 Figure 10 Location of Jumpers and Connectors on the PWC22 Processor Receiver Board Mounting When installing PWD22 with the sensor support arm pro...

Page 46: ...mast See Figure 12 above NOTE Do not damage the RAINCAP plate 3 Connect the PWD22 mast cable power and signal cable to a fixed connector underneath the PWD22 housing 4 Test if the connector swings If...

Page 47: ...nd baud rate of the service terminal program If wrong characters are shown try other baud rates such as 300 1200 2400 and 4800 5 Wait for 20 seconds and enter into the command mode with the OPEN comma...

Page 48: ...and the connector terminals are exposed to weather Basic Wiring The PWD22 cable has 16 connection wires Table 11 Receptable Connector Default Wiring Signal Name Connector in PWC Wire Color Sensor DC...

Page 49: ...ange is chosen by jumper X13 Heating power X3 5 WHT GRN Heating power X3 5 BRN GRN Heating power X3 6 WHT YEL Heating power X3 6 YEL BRN All four heating power wires must be connected due to high curr...

Page 50: ...ply the internal heaters too When separate heater power is applied it can be used to supply internal heaters Choosing whether to use or not separate supply for internal heaters is done by jumpers X5 a...

Page 51: ...e with two interfaces The two wire RS 485 is intended to be the standard interface The PWD22 software is designed to allow the RS 232 interface to be used as a service line when the RS 485 interface i...

Page 52: ...s Connection of the Maintenance Terminal Any computer equipped with terminal emulation software or a VT 100 compatible terminal with RS 232 serial interface can be used as a Maintenance Terminal for P...

Page 53: ...1 and LIMIT 2 1 ON 2 OFF When visibility is lower than LIMIT 1 but higher than LIMIT 2 1 ON 2 ON When visibility is lower than LIMIT 1 and LIMIT 2 Below is a table of a control logic example of relay...

Page 54: ...red by default NOTE Do not load any of the relay control output pins by more than 35 mA or any Ext Vb voltage output pin by more than 200 mA If external relays require higher coil current an external...

Page 55: ...2 Relay 3 wires X4 5 VIO X4 6 GRY PNK X4 7 RED BLU X4 8 PWC12 board Cable Box GND 12V 0309 045 Figure 17 Relay Connection External Relay Supply RELAY Command Set display the relay control states When...

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Page 57: ...iven in the command mode see section Entering and Exiting the Command Mode on page 56 PWD22 has four different standard message formats for data message output It presents the weather type using the W...

Page 58: ...ons Operation Commands Sensor cleaning CLEAN optional Visibility calibration ZERO CHECK CAL The standard output messages contain a status character which presents the results of the internal diagnosti...

Page 59: ...ber PWD22 answers as follows LINE OPENED FOR OPERATOR COMMANDS If no input is given within 60 seconds PWD22 closes the line automatically CLOSE The CLOSE command is used for releasing the line to auto...

Page 60: ...10 min ave visibility FIELD one minute average visibility DESCRIPTIONS 1 hardware error 2 hardware warning 3 backscatter alarm 4 backscatter warning 1 visibility alarm 1 2 visibility alarm 2 3 visibil...

Page 61: ...sage 1 displays the one minute average visibility instant precipitation type and the one minute average water intensity 00 1839 61 0 3 water intensity 1min ave mm h instant precipitation type 0 99 vis...

Page 62: ...20000m visibility one minute average max 20000m 1 hardware error 2 hardware warning 3 backscatter alarm 4 backscatter warning 1 visibility alarm 1 2 visibility alarm 2 3 visibility alarm 3 The follow...

Page 63: ...inute average max 20000m 1 hardware error 2 hardware warning 3 backscatter alarm 4 backscatter warning 1 visibility alarm 1 2 visibility alarm 2 3 visibility alarm 3 RA instant METAR weather codes RER...

Page 64: ...ing is used Message_interval Given in multiples of 15 s measuring interval Therefore intervals 15 30 45 are valid Other intervals are converted to multiples of 15 s Maximum sending interval is 255 s 4...

Page 65: ...cter 13 hex Carriage Return ASCII character 05 hex CTRL E id Selected in the configuration message number This is optional ASCII character 13 hex Carriage Return When the PWD22 unit number two ID 1 is...

Page 66: ...ng commands because the data message formats and framing are the same as in the VAISALA FD12 and FD12P sensors If PWD22 is polled by FD 1 2 the answer will start with FD 1 Precipitation Sums PWD22 has...

Page 67: ...RS Clears precipitation sums STA Displays status PAR Parameter message HIST Parameter For Vaisala systems use INTV Time For Vaisala systems use TIME hh mm ss Set Display system time DATE yyyy mm dd Se...

Page 68: ...r The valid range is 0 4 and 7 For example when choosing the data message number 0 type the following MES 0 AMES The AMES command defines the message which PWD22 transmits as the automatic message or...

Page 69: ...interval ignores the automatic sending This is used when messages are polled For details refer to section Automatic Message Sending on page 62 For example the following command selects message number...

Page 70: ...GHT SNOW LIMIT 1200 DRD SCALE 1 0 DRD DRY OFFSET 809 5 DRD WET SCALE 0 0017 WSET The WSET command is used to modify the present weather analysis parameters The WSET command asks for one parameter at a...

Page 71: ...cale is 1 0 Since the optimal value depends on the optical optoelectronic and electronic parameters in a very complex way no applicable factory calibration method has been developed yet Heavy rain lim...

Page 72: ...T PWD_AMOUNT where OLDSCALE The old value of rain intensity scale REF_AMOUNT The amount measured with the reference rain gauge PWD_AMOUNT The corresponding amount measured by PWD22 CLRS The CLRS comma...

Page 73: ...5 RECEIVER 300 CONTAMINATION ALARM LIMITS TRANSMITTER 3 0 RECEIVER 600 SIGN SIGNAL 1 1 000 DAC MODE EXT1 MAX VIS 20000 20 0 mA MIN VIS 180 4 5 mA 20 mA SCALE_1 184 6 SC_0 2 8 1 mA SCALE_1 184 8 SC_0...

Page 74: ...parameters a four character password can be set If no password is set the command continues as if it had the correct password When no password has been set the command is the following CONF When a pa...

Page 75: ...Y 5 TRANSMITTER CONTAMINATION LIMITS WARNING LIMIT 0 5 ALARM LIMIT 3 0 RECEIVER CONTAMINATION LIMITS WARNING LIMIT 300 ALARM LIMIT 600 ANALOG OUTPUT MODE 0 LINEAR 1 LN 2 EXTI 3 VG1 4 VG2 4 ANALOG OUTP...

Page 76: ...tion session is explained in the following The currently measured offset value not a parameter is shown in the brackets OFFSET 136 86 Y OFFSET REFERENCE UPDATED After receiving the Y answer the system...

Page 77: ...13 V where 0 V is a blocked lens The limit value is given as a positive value although the signal becomes smaller when contamination increases A contamination change of 5 V represents about a 10 decr...

Page 78: ...changed by the following operator command BAUD value communication_type Baud rates 300 1200 2400 4800 9600 Communication types E 7E1 and N 8N1 The new value is saved in EEPROM and it is used also afte...

Page 79: ...e PWD cable is so long that the 12 V power output is not adequate the analog output connection will be done as shown in Figure 20 on page 78 When the external power output is used one unused wire must...

Page 80: ...us the maximum value of the analog output may be set higher whereas the actual output is limited by the sensor s range The MIN VISIBILITY limits the low end If the abs max current minus min current is...

Page 81: ...S VIS VIS VIS VIS X i i coeff where VISi Initial visibility value in meters VISmin Lowest visibility value specified in configuration e g 10 m or 100 m VISmax Corresponding maximum visibility value e...

Page 82: ...lated from Iout by using DAC scale parameters Mode 3 Mode 3 is the Videograph mode that is non linear The visibility range from 100 m to 10000 m corresponds to the current range of 1 0 mA Mode 4 Mode...

Page 83: ...e DAC hardware and asks for the corresponding currents The currents can be measured with a standard calibrated multimeter 4 PWD22 calculates the bits current scales Following is an example of the cali...

Page 84: ...ts clean references ZERO Displays zero and noise test status CHEC Displays calibrator test signal DRY ON Sets RAINCAP dry offset WET ON Sets RAINCAP wet scale TCAL Sets the TS temperature ambient HEAT...

Page 85: ...ased more than the ALARM limit given in the configuration allows Transmitter Error LEDI signal is more than 7 V or less than 8 V 12 V Power Error Receiver transmitter power is less than 10 V or more t...

Page 86: ...s of the glass plates Typically the signal is close to 500 Hz PWD22 calculates a new scaling factor and stores it in the non volatile memory EEPROM NOTE If the PWC22 board has been changed and the sta...

Page 87: ...sage is shown Give the following command ZERO The output is the following ZERO SIGNAL OK Or in the case of failure in the receiver PWC22 on e of the following ZERO SIGNAL FAIL ZERO SIGNAL NOISE HIGH C...

Page 88: ...also the weather conditions must be dry The output is the following DRD DRY OFFSET 715 6 The DRY OFFSET value must be between 700 and 900 when the RAINCAP hardware operates normally The DRY command wi...

Page 89: ...N When you want to stop the heater test and quit the test mode press ESC NOTE Do not leave the heater testing on in warm conditions for long periods of time Other Commands TIME The TIME command is use...

Page 90: ...________________________________M210543EN B DATE The DATE command is used to display the current date To set a new system date type the following DATE yyyy mm dd where yyyy year mm month dd day RESET...

Page 91: ...CAP Rain Detector Checking the visibility calibration and calibrating it if necessary PWD22 is designed to operate continuously for several years without other maintenance than cleaning of the lenses...

Page 92: ...power OFF ON for example Cleaning Lenses and Hoods The lenses of the PWD22 transmitter and receiver units should be relatively clean to get reliable results as dirty lenses give too good visibility v...

Page 93: ...ouching grounded metallic parts of the installation to remove excessive static charges from your body Clean the RAINCAP rain detector carefully with a soft lint free cloth moistened with mild detergen...

Page 94: ...and a very high scatter signal The zero signal is obtained using a blocking plate and the high signal using opaque glass plates When visibility measurement is calibrated visibility should be better t...

Page 95: ...ed during the following steps 6 Move away from the optical path and wait for 30 seconds 7 Give the CHEC command 8 After one minute read the displayed signal 9 The signal value must be close to the one...

Page 96: ...ored Check PWD22 and the calibrator for hardware or mechanical errors Also consult Vaisala If the optical units PWC22 or PWT11 have been replaced the new scaling factor might change more than 20 from...

Page 97: ...remove the transmitter cover and the gasket 2 Disconnect the control cable connector 2 3 Loosen the set screw 3 to release the transmitter module 5 4 Pull the module out of the transmitter head by pry...

Page 98: ...Be careful not to touch the lens Make sure that the module seats properly If not lead it to the sink by pointed pliers 4 Lock the module with a M4x4 set screw 5 Connect control cable 1 and make sure...

Page 99: ...RAINCAP 1 Open the control box see section Removing PWC22 on page 96 2 Unplug the rain sensor cables X6 and X7 3 Remove the two screws below RAINCAP 4 Remove RAINCAP by pulling it out of the control...

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Page 101: ...performed by qualified personnel Message Indicating Warning or Alarm 1 Open the command mode and check the status information with the STA command or poll Message 3 to get the same information See sec...

Page 102: ...e 3 Go to the site Take the maintenance PC terminal tools and the calibrator set with you 4 Is PWD22 powered Open the PWC22 electronics enclosure cover and see if the Run and Signal Offset LEDs are bl...

Page 103: ...in section Removing and Replacing on page 94 when removing the units Visually inspect the condition of the electronics Visibility Value is Continuously Too Good This can be caused by several reasons...

Page 104: ...there are no flashing lights close to PWD22 Flashing lights may cause PWD22 to detect peaks in the optical signal 2 Check that there are no foreign objects in the sample volume Tree branches or other...

Page 105: ...t is too high Otherwise increase RAINCAP scale the WSET command PWD22 Electrical Troubleshooting PWD22 is protected against reverse polarity connected to power feed wires If the power feed is connecte...

Page 106: ...on set up of terminal Try with other expected baud rates 6 If the LEDs are not lit check the internal connector connections of PWD22 The following measurement can be done Measure the input voltage X1...

Page 107: ...environment When did it fail date immediately after a while periodically randomly How many failed only one defect other same or similar defects several failures in one unit What was connected to the...

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Page 109: ..._______________________107 CHAPTER 8 TECHNICAL DATA This chapter provides the technical data of the Product Specifications Mechanical Specifications Table 20 PWD22 Specifications Property Description...

Page 110: ...tor Output data Automatic or polled data messages Visibility present weather precipitation and status data Automatic message type and interval is selectable at 15 s n x 15 s n 18 intervals Auxiliary d...

Page 111: ...ange of MOR 1 10 20000 m Accuracy 10 range 10 10000 m 15 range 10km 20 km Instrument consistency 5 Time constant 60 seconds Update interval 15 seconds 1 Meteorological Optical Range Weather Sensing Sp...

Page 112: ...___________________________________________M210543EN B Environmental Specifications Table 26 Environmental Specifications Property Description Value Operating temperature range 40 55 C Operating humid...

Page 113: ...surface snow etc to the receiver Check the orientation of PWD22 OFFSET Measurement signal offset The lowest frequency for measurement signal 140Hz 150Hz 80 Hz 170 Hz 80 Hz 170 Hz OFFSET ERROR Drifting...

Page 114: ...nces from the optical path 2 Replace the clean contamination setting by giving the CLEAN command 3 Change the PWC22 control unit TR BACKSCATTER Control signal for the transmitter contamination CHANGE...

Page 115: ...oard Some degrees higher than ambient temp SIGNAL Frequency of the transmission signal between transducer and CPU Hz inversely proportional to visibility 0 00 Hz 10000 00 Hz SIGNAL ERROR Signal freque...

Page 116: ...wrong M12 measurement may also fail due to heavy electrostatic discharge to RAINCAP plate 1 Reset 2 Disconnect transmitter 3 Change the PWC22 control unit DRD Instant value of RAINCAP Rain Sensor 64 9...

Page 117: ...d Luminance Sensor PWL111 Range YEL X3 2 Background Luminance Sensor PWL111 Level GRN X3 3 Background Luminance Sensor PWL111 5 VA RED X3 4 Background Luminance Sensor PWL111 AGND BLK X3 5 Separate he...

Page 118: ...ward tilted plate is connected to X6 in double rain plate assemblies at PWD22 X7 RAINCAP connector No 2 is used in PWD22 only backward tilted plate X9 Reset X10 1 5 VA X10 2 AUX CPU ADC input internal...

Page 119: ...ENDIX C NWS AND WMO CODE TABLES Table 28 Internal Weather Types and Supported NWS Codes Internal Weather Types NWS Codes NO PRECIPITATION C PRECIPITATION P DRIZZLE L RAIN R SNOW S SLEET IP FREEZING DR...

Page 120: ...e used if precipitation or fog is observed at the time of observation 30 FOG 31 Fog or ice fog in patches 32 Fog or ice fog has become thinner during the past hour 33 Fog or ice fog no appreciable cha...

Page 121: ...rs moderate 83 Rain showers heavy 84 Rain showers violent 32 mm h 85 Snow showers light 86 Snow showers moderate 87 Snow showers heavy Table 30 WMO METAR Codes Table 4678 Used by PWD22 Qualifier Weath...

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Page 123: ...103 Rain 69 calibration kit 91 92 CFR 10 CHEC 65 82 85 92 93 94 CLEAN 34 56 65 71 75 82 84 91 112 cleaning 9 18 56 84 89 90 91 Clear sums 70 CLOSE 45 57 62 65 90 CLRS 65 67 70 CMOS 10 Communication C...

Page 124: ...ng 57 62 63 64 66 74 Power Supply 15 108 Precipitation accumulation 69 70 Precipitation sensitivity 109 precipitation sums 65 67 Precipitation type 69 precipitation types 13 32 PT 100 47 PWA11 18 84 8...

Page 125: ...temperature sensor 14 15 17 24 113 TIME 65 87 Transmitter 14 18 20 35 83 89 94 108 116 Troubleshooting 99 103 U Unpacking 40 user commands 55 V Vaisala 7 8 9 10 11 13 14 15 16 18 19 20 21 25 37 40 41...