0871LH1 Freezing Rain Sensor
Contents
1. Fari Oo Y Oo Re RS 422 Transmit RS 422 Transmit ICE Feedback EEPROM Figure B 1 Functional Block Diagram B 1 Appendix B Freezing Rain Sensor B 2 B1 1 Microcontroller The freezing rain sensor uses an Intel 87C51 type microcontroller to control the freezing rain sensor functions This 8 bit microcontroller requires at least 4 Kbytes of on board ROM 128 bytes of RAM and 32 input output ports The freezing rain sensor uses about 75 of these resources Upgraded microcontrollers that provide more resources are available The microcontroller runs at 7 372 MHz B1 2 Watchdog Reset Circuit The watchdog timer reset circuit monitors the microcontroller and provides a reset pulse if not periodically toggled The watchdog also provides reset pulses on initial power up and holds the microcontroller in the reset state if the internal power supply falls below an acceptable voltage The watchdog indicates impending power loss so the ice detector can shut down ina known manner B1 3 Serial EEPROM The Serial EEPROM stores unit status icing state failure state heater state correlation count which is recovered after power interruptions of 200 ms or less This allows the unit to meet the power interruption requirements of RTCA DC 160C Section 16 Category Z Additionally the Serial EEPROM stores environmental and failure information such as unit elapsed time number of icing encounters number of failures a2. Reference Number whether the repair is under guarantee or not Please state the faults as clearly as possible and if the product is out of the guarantee period it should be accompanied by a purchase order Quotations for repairs can be given on request It is the policy of Campbell Scientific to protect the health of its employees and provide a safe working environment in support of this policy a Declaration of Hazardous Material and Decontamination form will be issued for completion When returning equipment the Repair Reference Number must be clearly marked on the outside of the package Complete the Declaration of Hazardous Material and Decontamination form and ensure a completed copy is returned with your goods Please note your Repair may not be processed if you do not include a copy of this form and Campbell Scientific Ltd reserves the right to return goods at the customers expense Note that goods sent air freight are subject to Customs clearance fees which Campbell Scientific will charge to customers In many cases these charges are greater than the cost of the repair CAMPBELL DT SCIENTIFIC Campbell Scientific Ltd Campbell Park 80 Hathern Road Shepshed Loughborough LE12 9GX UK Tel 44 0 1509 601141 Fax 44 0 1509 601091 Email support campbellsci co uk www campbellsci co uk PLEASE READ FIRST About this manual Please note that this manual was originally produced by Campbell Scientific Inc
3. The drive coil modulates the magnetic field of the magnetostrictive oscillator and causes an ultrasonic axial movement of the probe B1 7 Feedback Coil The feedback coil senses the movement of the probe and when employed in the probe oscillator circuit completes the feedback portion of the MSO B1 8 Heater The probe heater de ices the probe It is activated when the nominal icing trip point of 0 50 mm is reached and is turned off five seconds after the MSO has returned to at least 39 970 Hz the additional five seconds allows the strut probe time to shed the de bonded ice The maximum heater ON time is 25 seconds Ifthe probe frequency has not returned at least 39 970 Hz by that time a de ice failure is declared and the heaters are turned off An open circuit of the heater is detected by the microcontroller B1 9 DC Power Supply The DC power supply provides 24 VDC for the heater circuitry Internal circuitry converts the 24 VDC input power to 5 VDC for use by the microcontroller and associated circuits It employs a large input capacitor to provide enough time between detection of input power loss and actual loss of DC power for the microcontroller to store the current unity status in the non volatile memory The DC power supply provides input transient protection to meet RTCA DO 160C power input voltage spike and lightning requirements B1 10 Status Output The status output provides a ground output when the freezing rain s
4. change in collection efficiency caused by ice build up Upon reaching a correlation count of 255 the value is no longer incremented The freezing rain sensor compensates by adding a value ranging from 0 to 6 to the correlation count when the ice detection cycle is completed to account for the ice that would have accumulated if the heater had not been on The correlation count is in the serial string Table A 2 Serial String Format The correlation count is initialized to zero at unit power up Appendix A RS 422 Output Format A 9 Ice Detector RS 422 String Format Table A 2 Serial String Format Byte Bit Definition Comments Interpretation Range 0 First 7 MSB String ID Presently defined as 00 6 May add additional strings in future 5 3 Unused 2 Probe Heater State 1 Heater On 0 Heater Off 1 Ice Output 1 Ice 0 No Ice 0 Status Output 1 Fail 0 OK No Fail 1 2 MSO FREQUENCY MSO Count in Hex Frequency 774060000 Dec MSO 3 ERRSTATI Unused 1 Active O TG Wish rato Ps Ms Fail Too Low pia EEPROM Fal PRAM el RO at a o e Power Interrupt Timer Fail Probe Heater Failure 00 Probe Heater OK 01 Probe Heater Always ON or OPEN 10 Probe Heater Always OFF 11 Probe Heater ON with 1 Enable O S 5 Dpeicingrail 1 Active TA a es ee a ooo qunsed TT used 0 a 5 7 ON TIME CNT Foyer On Tune hye 2 00 01 BEBE 10 Minute Increments 8
5. on the probe temperature can exceed 204 4 C Maintenance personnel should exercise caution when servicing the unit 7 Power Interruptions The freezing rain sensor is qualified to DO 160C power input category Z The unit will remember status through a 200 ms power interruption but the output string will cease during the interruption 0871LH1 Freezing Rain Sensor The freezing rain sensor uses a power fail monitor to verify the supply voltage If a power fault is detected the freezing rain sensor is halted with a failure indication on the STATUS discrete output 8 Mounting Considerations Prevailing Wind 20 30 degrees Figure 4 Mounting part 0871LH1 MNT The freezing rain sensor should be mounted to a sturdy crossarm located away from buildings or other obstacles that could shadow the sensing element from freezing rain The sensor should be installed so that the sensing probe is a minimum of 92 cm 36 above the ground 1 Remove the protective tube from strut 2 Attach the freezing rain sensor to the mounting bracket using the supplied 1 4 20 screws and lock washers Position the freezing rain sensor on the mounting pole with the sensing probe pointing upward with the bracket inclined at a 20 30 angle above horizontal to ensure proper drainage of melted ice 3 Attach to a vertical or horizontal pipe using the supplied V bolts nuts and washers NOTE The sensor should be mounted so as to be
6. ordering Recycling information At the end of this product s life it should not be put in commercial or domestic refuse but sent for recycling Any batteries contained within the product or used during the products life should be removed from the product and also be sent to an appropriate recycling facility Campbell Scientific Ltd can advise on the recycling of the equipment and in some cases Sz arrange collection and the correct disposal of it although charges may apply for some items or territories For further advice or support please contact Campbell Scientific Ltd or your local agent fz CAMPBELL LT SCIENTIFIC Campbell Scientific Ltd Campbell Park 80 Hather Road Shepshed Loughborough LE12 9GX UK Tel 44 0 1509 601141 Fax 44 0 1509 601091 Email support campbellsci co uk www campbellsci co uk Contents PDF viewers note These page numbers refer to the printed version ofthis document Use the Adobe Acrobat bookmarks tab for links to specific sections Mes SPU DOS aa 1 Bu e PeR A 1 3 Detailed Principle of Operation 1 4 Specifications 3 5 Physical Description rreren 4 6 Temperature Considerations 5 7 Power Interruptions eeee cece cette eee rnrn 5 8 Mounting Considerations 6 Si WIFING storti ER RR E ERER ERR 7 9 1 0871LH1CBL L Wiri
7. primarily for the North American market Some spellings weights and measures may reflect this origin Some useful conversion factors Area lin square inch 645 mm Mass 1 oz ounce 28 35 g 1 Ib pound weight 0 454 kg Length lin inch 25 4 mm 1 ft foot 304 8 mm Pressure 1 psi Ib in 68 95 mb 1 yard 0 914 m 1 mile 1 609 km Volume 1 UK pint 568 3 ml 1 UK gallon 4 546 litres 1 US gallon 3 785 litres In addition while most of the information in the manual is correct for all countries certain information is specific to the North American market and so may not be applicable to European users Differences include the U S standard external power supply details where some information for example the AC transformer input voltage will not be applicable for British European use Please note however that when a power supply adapter is ordered it will be suitable for use in your country Reference to some radio transmitters digital cell phones and aerials may also not be applicable according to your locality Some brackets shields and enclosure options including wiring are not sold as standard items in the European market in some cases alternatives are offered Details of the alternatives will be covered in separate manuals Part numbers prefixed with a symbol are special order parts for use with non EU variants or for special installations Please quote the full part number with the when
8. 9 COLD START CNT Cold Start Power On Count 00 FFFF 10 11 ICE CNT Ice Events 00 FFFF 12 FAIL CNT Total Failures Encountered 00 FF This number is incremented each time the ice detector transitions from OK to fail 13 FAIL DTL 1 7 4 MSO Frequency Fail Count 0 F 3 0 Heater Fail Count 0 F 14 FAIL DTL 2 7 4 Not Used Not Used 3 0 Not Used Not Used 15 LAST ERR 1 See ERRSTATI Above Appendix A RS 422 Output Format 16 LAST ERR 2 See ERRSTAT2 Above 17 2ND LAST ERR 1 See ERRSTATI Above 18 2ND LAST ERR 2 See ERRSTAT2 Above 19 PERM ERR See ERRSTAT1 Above 20 PERM ERR 2 See ERRSTAT2 Above i Software Version per 21 Software Version 7 0 VDD SC1 P 0 FF 22 Correlation Count 7 0 0 01 ice accretion 0 FF increments since power on 23 CHECKSUM Summation 1 byte wide of 0 FF bytes 0 22 A 10 Electrostatic Discharge ESD Consideration The freezing rain sensor internal components are ESD sensitive class 1 so proper ESD precautions must be observed wrist straps conductive surfaces when handling Appendix B Freezing Rain Sensor B 1 Freezing Rain Sensor Block Diagram The block diagram in Figure B 1 Functional Block Diagram provides an understanding of the functionality of the freezing rain sensor Drive Feedback Coil Coil Probe Heater Probe Oscillator 24 VDC return Heater Control Voltage Monitor amp Watchdog Timer Connector pe L
9. A Public Variables from 0871LH1 Sensor via RS 422 Output Ikkxkxk xkxkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk Public LH1 Serial Error As Boolean This is the decimal equivalent of Bytes 1 to 24 output by the 0871LH1 Public LHa_Byte 24 As Long String is 1 On or o Off Public LHa_Probe_Heater_State As String 3 String is 1 Ice or o No Ice 12 User Manual Public LHa_Ice_Output As String 6 String is 1 Fail o OK Public LH1 Status Output As String 4 String is 1 Fail o OK ERRSTAT1 Public LH1_ERR_MSO_TOO_HIGH As String 4 Public LH1_ERR_MSO_TOO_LOW As String 4 Public LH1_ERR_EEPROM As String 4 Public LH1_ERR_RAM As String 4 Public LH1_ERR_ROM As String 4 Public LH1_ERR_WATCHDOG As String 4 Public LH1_ERR_PWR_INT_TIMER As String 4 ERRSTAT2 Public LH1_ERR_DE_ICING As String 4 oo OK 01 Always On 10 Always Off 11 ON Public LH1_ERR_PROBE_HEATER As String 10 Public LH1_MSO_Frequency As Float Public LH1_ON_Time_Days As Float Public LH1 Cold Start Count As Float Public LH1 ICE Count As Float Public LH1 FAIL Count As Float Public LH1_MSO_FAIL_Count As Float Public LH1_Heater_FAIL_Count As Float Public LH1 Software Version As Float Public LH1_ICE_Count_From_PWR_ON As Float Public LHa_CHECKSUM As Long IKAKAKAKAAKAAKAAAAAAAAAAAAAAKAKAAKAAKAAAAAAAAAAAKAAAAAAAAAAAAAAAAAKAAAAAAAAAAAAAAAKAAAAAAATA
10. AAAAAAAAA END Public Variables for 0871LH1 RS 422 Output KKKKKKKK KKK KKK AAA AE KKK KKK KKK KEK KKK KEKE KKK KK KK KKK KKK KKK KKK KKK ERK RRR KK KK EKER KKK KK KKK KKEKKKKKKKKKKE Define Data Tables PLEASE NOTE The majority of 0871LH1 outputs are diagnostic in nature Add to Data Table s as required for your application DataTable LH1_output 1 1000 Datalnterval 0 15 Sec 10 Minimum 1 batt_volt FP2 0 False Sample 1 PTemp FP2 Sample 1 Ice IEEE4 Sample 2 lce_mm lEEE4 EndTable This Subroutine Sets all values to a Defaut Error State if Serial Communications do not work Sub LH1_Error_State LH1_Probe_Heater_State NAN LHa_Ice_Output NAN LHa_Status_Output NAN LHa_ERR_MSO_TOO_HIGH NAN LHa_ERR_MSO_TOO_LOW NAN LHa_ERR_EEPROM NAN LHa_ERR_RAM NAN LHa_ERR_ROM NAN LHa_ERR_WATCHDOG NAN LHa_ERR_PWR_INT_TIMER NAN LHa_ERR_DE_ICING NAN LHa_ERR_PROBE_HEATER NAN 13 0871LH1 Freezing Rain Sensor LHa_MSO_Frequency NAN LH1_ON_Time_Days NAN LH1_Cold_Start_Count NAN LHa_ICE_Count NAN LHa_FAIL_Count NAN LH1 MSO FAIL Count NAN LH1 Heater FAIL Count NAN LH1 Software Version NAN LH1_ICE_Count_From_PWR_ON NAN LHa_CHECKSUM NAN EndSub KAKAKAAAKAAKAAAAAAAAAAAAAAAKAAKAAKAAAAAAAAAAAKAAKAAAAAAAAAAAAAKAAKAAKAAAKAAAAAAAAAAAAAAAAAKRAARAAAAAAAAA o871LH1_GetData Subroutine Typically Takes 3 Seconds to execute Ikkxkxkxkxkxkxkkkkkkkkkkkkkkkkkkkkkkkk
11. AWA 0871LH1CBL L Terminal Expander Figure 5 General Hook up Diagram 9 2 0871LH1CBL L Wiring for RS422 Output NOTE The MD485 Multidrop Interface the L15966 Wall Charger and the SC110 Interface Cable are required to measure the RS422 output on a CR1000 or CR3000 NOTE The MD485 Multidrop Interface must be configured for Active Ports RS232 and RS485 RS232 Baud Rate 9600 and RS485 Baud Rate 9600 Refer to the MD485 Manual for configuration instructions Table 4 Datalogger Connections Description Pin Colour Sensor MD485 Sensor CR1000 CR3000 Ice F Blue N C N C Status G Yellow N C N C RS422 A D White RS485 A N C RS422 B E Brown RS485 B N C Power Reference B Black N C G Case GND C Green N C G 5V Power Purple N C G Shield Clear N C G NOTE WARNING User Manual If the application requires the monitoring of the discrete outputs the 5Vdc connection must be made problems if shorted to ground Isolate wires that are not connected as they may cause Table 5 Power Connections to Terminal Expander Description Pin Colour Connection 24VDC A Red V 24VDC Return B Black V Table 6 SC110 Connections Description Colour MD485 CR1000 CR3000 DB9 Male Connector RS 232 to DTE N C CR1000 Tx Brown N C C3 CR1000 Rx White N C C4 CR1000 Gnd Yellow N C G Shield Clear N C G 10 Program Examples It is poss
12. Failure x Appendix A RS 422 Output Format NOTEWhen the failure is enunciated the software no longer provides ice detection capability NOTEIn Continuous BIT the Probe Heater Always OFF failure is set when the heater is ON and a de icing failure has been detected If the frequency indicates that the ice has been removed within the expected time the software will not annunciate the probe heater failure The actual failure is most likely due to a problem in the heater feedback circuitry rather than heater control circuitry The failure will be enunciated the next time IBIT is performed A 6 Operator Initiated Tests CAUTION The operator can test the freezing rain sensor functionality by squeezing the tip of the probe between the index finger and thumb This simulates icing by decreasing the frequency of the probe With the sensor wired to the datalogger use a digital voltmeter DVM measure DC voltage signal between the Ice signal blue wire in control port and the power reference ground black wire in G terminal The voltage reading should be 4500mvDC to 5000mvDC When the probe tip of the ice detector is squeezed thus changing the frequency and tripping the probe the voltage reading will immediately drop to a reading below 500mvDC Observing this will verify that the probe is operating properly and give the user enough time to release the probe before it reaches its full heating temperature Once initiated the heatin
13. IVANVIA JASA NE CAMPBELL 5 SCIENTIFIC WHEN MEASUREMENTS MATTER 0871LH1 Freezing Rain Sensor ON ESD CAUTION AINS THIS EQUIPMENT cor 10 DEVICES SUSCEPTA FOSTATIO DAMAGE BY ELECTRO E ESD E DISCHARGE ESD TONS HANDLING PRECAU ED WHEN COV IS REMOVED ER Issued 27 1 14 Copyright 2007 2012 Campbell Scientific Canada Corp Printed under licence by Campbell Scientific Ltd CSL 742 Guarantee This equipment is guaranteed against defects in materials and workmanship This guarantee applies for twelve months from date of delivery We will repair or replace products which prove to be defective during the guarantee period provided they are returned to us prepaid The guarantee will not apply to e Equipment which has been modified or altered in any way without the written permission of Campbell Scientific e Batteries e Any product which has been subjected to misuse neglect acts of God or damage in transit Campbell Scientific will return guaranteed equipment by surface carrier prepaid Campbell Scientific will not reimburse the claimant for costs incurred in removing and or reinstalling equipment This guarantee and the Company s obligation thereunder is in lieu of all other guarantees expressed or implied including those of suitability and fitness for a particular purpose Campbell Scientific is not liable for consequential damage Please inform us before returning equipment and obtain a Repair
14. NT_TIMER OK Endlf If LHa_Byte 4 AND amp B10 lt gt o Then LH1_ERR_WATCHDOG FAIL Else LH1_ERR_WATCHDOG OK Endlf If LHa_Byte 4 AND amp B100 lt gt o Then LH1_ERR_ROM FAIL Else LH1_ERR_ROM OK Endlf If LHa_Byte 4 AND amp B1000 lt gt o Then LH1_ERR_RAM FAIL Else LH1_ERR_RAM OK Endlf If LHa_Byte 4 AND amp B10000 lt gt o Then LH1_ERR_EEPROM FAIL Else LH1_ERR_EEPROM OK Endlf If LHa_Byte 4 AND amp B100000 lt gt o Then LH1_ERR_MSO_TOO_LOW FAIL Else LH1_ERR_MSO_TOO_LOW OK Endlf If LHa_Byte 4 AND amp B1000000 lt gt o Then LH1_ERR_MSO_TOO_HIGH FAIL Else LH1_ERR_MSO_TOO_HIGH OK Endlf If LHa_Byte 5 AND amp Bo11000000 amp Booooo0000 Then LH1_ERR_PROBE_HEATER OK Elself LH1_Byte 5 AND amp Bo11000000 amp Bo1000000 Then LH1_ERR_PROBE_HEATER Always On Elself LH1_Byte 5 AND amp Bo11000000 amp B10000000 Then LH1_ERR_PROBE_HEATER Always Off Elself LH1_Byte 5 AND amp Bo11000000 amp B11000000 Then LH1_ERR_PROBE_HEATER On Endlf If LHa_Byte 5 AND amp Boo1000000 lt gt o Then LH1_ERR_DE_ICING FAIL Else LH1_ERR_DE_ICING OK Endlf o871LH1 output ON time in 10 Minute Increments User Manual LH1_ON_Time_Days LH1_Byte 6 lt lt 16 LH1_Byte 7 lt lt 8 LH1_Byte 8 144 LH1_Cold_Start_Count LH1_Byte g lt lt 8 LH1_Byte 10 LHa_ICE_Count LHi1
15. RS 422 RS422 Outputs Icing Signal Period for Icing and Status No Icing Open Icing Ground Status OK Ground Status Failure Open Hexidecimal 24 byte string ASCII format 9600 Baud 1 Start Bit 8 Data Bits No Parity 1 Stop Bit for Icing and Status No Icing 0 Icing 1 Status OK 0 Status Failure 1 60 second activation from start of icing measurement Discrete or RS 422 outputs 0871LH1 Freezing Rain Sensor Connector Pinout Table 1 0871LH1 Connector Pinout Connector Pin Signal Description A 24VDC B 24VDC Return C Case Ground D RS 422 High E RS 422 Low F Ice G Status Mating Connector MS27473T10B99SN De icing Control Automatically triggered with accumulation of 0 5mm of ice on probe Max heating time 25 seconds 5 Physical Description The freezing rain sensor is an integrated unit containing both the sensor and processing electronics It contains a 7 35 cm 2 9 square faceplate for mounting to the 0871LH1MNT and a 7 28 cm 2 86 diameter housing containing the processing electronics The maximum weight of a unit is 318 grams 0 7 lbs User Manual Bottom View Top View 1 22 jii O O Airflow 0 266 mi 3 0 265 0 366 2 88 0 25 o Probe All dimensions in inches MS27474T10B99P _ Figure 3 Ice Detector 6 Temperature Considerations In the case of unit malfunction causing strut heater lock
16. _Byte 11 lt lt 8 LH1_Byte 12 LHa_FAIL_Count LH1_Byte a3 LHa_MSO_FAIL_Count LH1_Byte 14 gt gt 4 LHa_Heater_FAIL_Count LHa_Byte 14 AND amp Boooo1111 LH1_Software_Version LH1_Byte 22 LHa_ICE_Count_From_PWR_ON LH1_Byte 23 Endif EndSub Main Program BeginProg Ensure that the proper Com port is defined for the Constant LHi_comport SerialOpen LH1_comport 9600 3 0 50 Scan 15 Sec 0 0 PanelTemp PTemp 250 Battery batt_volt Enter other measurement instructions Inteval Time for Reading the Ice Detector If TimelntoInterval 0 1 Min Then Read_LH1 True Read_LH1 True If Read_LH1 True Then Call LH1_GetData Read_LH1 False Endif PPP t t t t tt t t t t tt t t t NOTE The use of the Ice thickness calculation is discretionary and dependant on the application The maximum allowable ice is 0 02 before the heater turns on Formula used to convert the Frequency into Ice Thickness inches Ice 0 00015 LH1_MSO_Frequency 6 Convert ice accumulation from inches to millimeters Ice_mm Ice 25 4 PPP t t t t t t t t t t t t t t t t CallTable LH1 output NextScan EndProg 17 Appendix A RS 422 Output Format A 1 RS 422 Output Format for non Campbell Datalogger Applications This output operates at 9600 BAUD One Start Bit 8 Data Bits No Parity One Stop B
17. agnetic field Amagnet mounted inside the strut and modulated by a drive coil surrounding the lower half of the tube provides the magnetic field A magnetostrictive oscillator MSO circuit is created with the above components and the addition of a pickup coil and an electronic comparator The ultrasonic axial movement of the tube resulting from the activation of the drive coil causes a current to be induced in the pickup coil The current from the pickup coil drives the comparator that in turn provides the signal for the drive coil The oscillation frequency of the circuit is determined by the natural resonant frequency of the sensor tube which is tuned to 40 kHz With the start of an icing event ice collects on the sensing probe The added mass of accreted ice causes the frequency of the sensing probe to decrease in accordance with the laws of classical mechanics A 0 5 mm 0 020 thickness ofice on the probe causes the operating frequency of the probe to decrease by approximately 130 Hz The freezing rain sensor onboard software monitors the probe frequency detects and annunciates any frequency decrease At the same time the internal probe heater power is applied until the frequency rises to a predetermined set point pus an additional delay factor to assure complete de icing 0871LH1 Freezing Rain Sensor Once de iced the sensing probe cools within a few seconds and is ready to sense ice formation again When ice forms on the se
18. controller is reset no output string is sent Appendix A RS 422 Output Format A 4 Continuous Built In Test BIT Continuous BIT consists of verifying the following The probe heater is in the correct state The return leg of the heater is monitored The ICE discrete output is in the correct state The ICE discrete output is fed back to the microcontroller through a passive voltage divider and voltage comparator The MSO is operating correctly Frequencies between 39000 and 40150 Hz are valid The probe heater is de icing correctly After turn on the probe heater must cause the MSO frequency to return to at least 39970 Hz within the 25 second timeout or it is considered failed e Probe is de iced within 25 seconds De Icing Fail A 5 BIT Failure That Disables Ice Output The Ice output is disabled due to Continuous and Initiated BIT failures as shown in Table A 1 BIT Information Ice detection is disabled when these failures occur because the integrity of the ice detection capability has been compromised Table A 1 BIT Information LIA Initiated BIT Continuous BIT Title Detection MSO Fail High x MSO Fail Low x x EEPROM Fail x RAM Fail x x ROM Fail x Watchdog Fail x Power Interrupt Timer Fail X Ii Power Fault Monitor Fail x A me ONE Active Test Passive Test Probe Heater Always OFF Active Test Probe Heater ON w 1 Enable x De Icing Fail Clear Only Set Only Unknown Reset
19. csteeesteesseessteessteesneesate B 5 Appendices A RS 422 Output Format A 1 B Freezing Rain Sensor B 1 0871LH1 Freezing Rain Sensor 1 Purpose 2 General This document provides detailed information about the Rosemount Aerospace model 0871LH1 Freezing Rain Sensor for use in ground based meteorological applications Topics covered include requirements qualification categories and methodology and detailed design information The Rosemount Aerospace 0871LH1 Freezing Rain Sensor is a one piece unit that detects the presence of icing condition Twenty four volts DC input power is provided to the freezing rain sensor The freezing rain sensor outputs include ice detection indication and fault status indication These outputs are provided through an RS 422 interface and discrete outputs One freezing rain sensor is used on each station and provides the primary means of ice detection The ice signal is used to indicate to the operator that an icing condition exists so that appropriate actions can be taken 3 Detailed Principle of Operation The freezing rain sensor uses an ultrasonically axially vibrating probe to detect the presence of icing conditions The sensing probe is a nickel alloy tube mounted in the strut at its midpoint node with one inch exposed to the elements This tube exhibits magnetostrictive properties it expands and contracts under the influence of a variable m
20. ensor is operating correctly and high impedance 200 KQ minimum when the unit has detected a failure Failures are detected through continuous and initiated tests The Status output is capable of sinking 50 mA and is guaranteed to be no more than 1 5 VDC with respect to Signal Return when active This output is transient protected to meet RTCA DO 160C lightning requirements and to prevent stray high voltage from coupling into the unit and damaging the output transistor B1 11 Ice Signal Output The Ice Signal output provides a ground output for 60 6 seconds when the ice detector has detected the presence of ice frequency drop of 130 Hz equivalent to approximately 0 50 mm ice formation If the frequency subsequently decreases by 130 Hz while the Ice Signal output timer is non zero the timer is reinitialized to 60 seconds B 3 Appendix B Freezing Rain Sensor The output is transient protected to meet RTCA DO 160C lightning requirements and to prevent stray high voltage from coupling into the unit and damaging the output transistor The ice output has feedback to the microcontroller for software to verify it is in the correct state for more built in test coverage The software in the 0871KB2 model uses this feedback to verify that the ice output is operating correctly To interface to the 0871LH1 the power supply must provide a pull up of 5 3 volts maximum When the ice output is inactive open the nominal resistance to ground
21. fic do Brazil Ltda CSB Rua Luisa Crapsi Orsi 15 Butanta CEP 005543 000 Sao Paulo SP BRAZIL www campbellsci com br e suporte campbellsci com br Campbell Scientific Canada Corp CSC 11564 149th Street NW Edmonton Alberta TSM 1W7 CANADA www campbellsci ca e dataloggers campbellsci ca Campbell Scientific Centro Caribe S A CSCC 300N Cementerio Edificio Breller Santo Domingo Heredia 40305 COSTA RICA www campbellsci cc e info campbellsci cc Campbell Scientific Ltd CSL Campbell Park 80 Hathern Road Shepshed Loughborough LE12 9GX UNITED KINGDOM www campbellsci co uk e sales campbellsci co uk Campbell Scientific Ltd France 3 Avenue de la Division Leclerc 92160 ANTONY FRANCE www campbellsci fr e info campbellsci fr Campbell Scientific Spain S L Avda Pompeu Fabra 7 9 Local 1 08024 BARCELONA SPAIN www campbellsci es e info campbellsci es Campbell Scientific Ltd Germany Fahrenheitstrasse13 D 28359 Bremen GERMANY www campbellsci de e info campbellsci de Please visit www campbellsci com to obtain contact information for your local US or International representative
22. g de icing sequence will quickly heat the probe to 204 4 C Though bare fingers must be used for a reliable test result there is a danger that you will burn your fingers if you do not let go when heating has been verified A 7 Initiated Built In Test BIT Initiated BIT is performed at initial power up of the freezing rain sensor and following power interruptions of not less than 200 ms Initiated BIT consists of the following tests e The ice and fault status outputs are set in the RS 422 string and on the discrete outputs so monitoring electronics or test equipment can verify activation e The freezing rain sensor heater is turned on for a short period of time to verify correct operation of the heater heater control circuit and heater feedback circuit e Correct operation of the watchdog timer is verified by simulating a microcontroller time out and waiting for a reset input Appendix A RS 422 Output Format e Proper ROM operation is verified by computing a checksum of the ROM contents and comparing against a checksum stored in the ROM e RAM operation is verified by writing and reading test bytes e The Power Interrupt Timer is checked by verifying its transitions to a warm state after performing a cold start The power fail input is pulled down to verify a power failure is detected e Each time the critical data from the Serial EEPROM is read a checksum is read and compared to the checksum computed f
23. g and status Based on scan rate PortGet IceSignal 1 PortGet StatusSignal 2 If a status fault is detected then the status code is stored to the Sensor Status data table Only fault status data is stored to the table If StatusSignal 1 Then CallTable Sensor_Status Endif If an icing event is detected then store the record to the Ice Condition data table If IceSignal o Then CallTable Ice_Condition Reset the datalogger counter during icing events so that data is coordinated with the sensors counter Timer 1 Sec 3 Endlf Endlf NextScan EndProg 10 2 CR23X Example Discrete Outputs User Manual Set Timer input location 1 Timer P26 1 3 Loc Timer Use Timer to monitor Control Ports 1 amp 2 every 61 seconds 2 If X lt gt F P89 1 3 XLoc Timer 2 3 gt 3 61 F 4 30 Then Do 3 Set Port s P20 1 9999 C8 C5 nc nc nc nc 2 9988 C4 C1 nc nc input input Read the status of the ports and store to input locations for comparison 4 Read Ports P25 1 1 Mask 0 255 2 2 Loc IceStat 5 Read Ports P25 1 2 Mask 0 255 2 1 Loc FaultStat Check to see if there is a fault in the sensor and output it to final storage 6 If X lt gt F P89 1 1 XLoc FaultStat 2 1 3 1 F 4 30 Then Do 7 Do P86 1 10 Set Output Flag High Flag o 8 Set Active Storage Area P80 3085 1 1 Final Storage Area 1 2 10 Array ID g Real Time P77 1712 1 1220 Year Day Hour M
24. ible to collect icing information either by the discrete outputs of the 10 1 CR1000 Example Discrete Outputs 0871LHI or the available RS422 output Monitor the discrete outputs of the 0871LH1 for icing events and changes to the sensor status Data tables are updated only after an icing event or status change occurs 0871LH1 Freezing Rain Sensor 10 Declare Public Variables Public TimeCount Public IceSignal ice signal Open no ice Ground ice Public StatusSignal status signal Ground okay Open fault Define Data Tables DataTable Sensor_Status True 1 Sample 1 StatusSignal FP2 EndTable DataTable Ice_Condition True 1 Sample 1 IceSignal FP2 EndTable Main Program BeginProg In order for the datalogger to receive data from the 0871LH1 ports 1 amp 2 must be configured as inputs PortsConfig amp B11 amp Boo Scan 5 Sec 0 0 Start timer to corrdinate monitoring of ice signal output from sensor TimeCount Timer 1 Sec 0 During icing event the sensor cycles through a 60 second monitoring interval When the first icing event occurs a 60 second counter is started in the sensor Once the 60 seconds have pasted the sensor will determine if further icing has occurred If yes the sensor signals the icing event heats the probe and resets counter If no the sensor signals no ice and resets counter If TimeCount gt 61 Then Record sensor outputs for icin
25. inute midnight 2400 10 Sample P70 23951 1 1 Reps 2 1 Loc FaultStat 11 End P95 Check to see if there is Ice on the sensor and output it to final storage 12 If X lt gt F P89 1 2 X Loc lceStat 2 1 3 0 F 4 30 Then Do 13 Do P86 1 10 Set Output Flag High Flag 0 14 Set Active Storage Area P80 10755 11 0871LH1 Freezing Rain Sensor 1 1 Final Storage Area 1 2 20 Array ID 15 Real Time P77 8112 1 1220 Year Day Hour Minute midnight 2400 16 Sample P70 5446 1 1 Reps 2 2 Loc IceStat jlf there is ice on the unit start a looping sequence that ends only when ice is no longer detected 17 Timer P26 1 0 Reset Timer 18 End P95 19 End P95 10 3 CR1000 Example RS422 Outputs NOTE The MD485 Multidrop Interface the L15966 Wall Charger and the SC110 Interface Cable are required to measure the RS422 output on a CR1000 or CR3000 NOTE The MD485 Multidrop Interface must be configured for Active Ports RS232 and RS485 RS232 Baud Rate 9600 and RS485 Baud Rate 9600 Refer to the MD485 Manual for configuration instructions CR1000 Series Datalogger Declare Public Variables Public PTemp batt_volt Public LHa_Byte_Count As Float Public Read_LH1 As Boolean Public Ice Public Ice mm Define the Comport for the o871LHa here Const LHi_comport Com2 IKAKAKAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
26. is 10 1 KQ The power supply should source at least 0 250 mA to provide the proper signal to the Ice Signal feedback circuitry When the output is active closed it is capable of sinking 50 mA and is guaranteed to be no more than 1 5 VDC with respect to Signal Return B 2 Qualification Capabilities Table B 1 0871LH1 Ice Detector Qualification Capabilities Test Name Test Requirement EMC DO 160C Audio Freq Susc Cat Z Induced Signal Cat Z Susc Chg Notice 3 Cat R RF Susceptibility Cat Z RF Emissions Cat Z Lightning Induced Susceptibility DO 160C Multiple Burst Waveform 3 amp 4 Level 3 Multiple Stroke Waveform 3 Level 3 Temperature Variation DO 160C Cat A Temperature Altitude DO 160C Cat D2 40 C to 71 C Vibration DO 160C Cat E Random 7 9 grms Operation Shock Crash Safety DO 160C Shock Salt Spray DO 160C Cat S Humidity DO 160C Cat B Icing Performance Rosemount Aerospace Inc Test Procedure Power Input DO 160C Cat Z 18 29 5 VDC Voltage Spike DO 160C Cat A Magnetic Effect DO 160C Cat A 1 deflection at 0 5m Bonding 2 5 mW Max Mounting Plate to Aircraft Structure 10 mW Max Connector Shell to Mounting Plate Dielectric Withstanding MIL STD 202 500 VAC 60 Hz EMI Filters Disconnected Insulation Resistance MIL STD 202 500 VDC 1000 MW EMI Filters Disconnected Fluid Susceptibility DO 160C Cat F Wa
27. it A 24 byte string is sent once per second See Section 9 Table 3 for string definition A two line output provides a unidirectional serial port running at 9600 BAUD 8 bits one Start Bit One Stop Bit no parity to allow communication with aircraft electronics and external test equipment A 2 Built In Test BIT Built In Test BIT capabilities of the freezing rain sensor consist of hardware continuous power up and operator initiated tests Whenever a failure is detected and verified the freezing rain sensor stops detecting and annunciating icing conditions and the heaters are disabled Failures detected in Initiated and Continuous BIT are counted and enunciated once they have been verified To eliminate nuisance errors failures are verified by delaying debouncing the failure for a period of time Failures detected in Initiated BIT are latched and power must be cycled on and off to remove a failure If failures detected in Continuous BIT go away the ice detector changes back to normal mode and once again enables all ice detection functions A 3 Hardware Built In Test BIT Hardware BIT is comprised of a watchdog timer that forces the microcontroller to re initialize if it does not receive a strobe every 1 6 seconds An internal voltage monitor forces the microcontroller to the reset state if the internal 5VDC power supply falls below 4 65 VDC and holds it there until the power supply returns above 4 65 VDC When the micro
28. kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk Use an MD485 configured to RS 485 RS 232 Transparent Mode 9600 BAUD for RS 232 and RS 485 Sub LH1_GetData Dim Stay_In_Loop As Boolean Dim CheckForBlankTime As Boolean Dim LoopCounter Dim Old_Byte_Count As Float Dim TimeSinceLastByte As Float Dim LHa_Raw_In_Buff As String 50 SerialFlush LH1_comport Obtain the current byte count Old_Byte_Count SeriallnChk LHa_comport Initializations reset and start the timer Timer 1 mSec 2 CheckForBlankTime False LH1_Serial_Error False Stay_In_Loop True While Stay_In_Loop True Get the existing byte count LH1_Byte_Count SeriallnChk LH1_comport reset the timer ifthe byte cound is not the same If LHa_Byte_Count lt gt Old Byte Count Then update the byte count Old_Byte_Count LH1 Byte Count reset and start the timer Timer 1 mSec 2 Received at least one byte start checking for a blank time CheckForBlankTime True Endlf Obtain the time from the last byte TimeSinceLastByte Timer 1 mSec 4 If CheckForBlankTime True Then If no characters occur within 100 msec of last byte then assume end of packet If TimeSinceLastByte gt 100 Then Stay In Loop False Endlf Exit regardless if more than 3 seconds elapse 14 User Manual If TimeSinceLastByte gt 3000 Then LH1_Serial_Error True Stay_In_Loop False Endif Wend If LHa_Serial_Error False The
29. n Flush the buffer SerialFlush LH1_comport Wait a mximum of 2 seconds If Timer 2 mSec 4 gt 2000 Then LH1_Serial_Error TRUE Stay_In_Loop False Endif Wend Obtain a CheckSum and convert All Binary Values LHa1_CHECKSUM 0 Convert allthe BINARY Values For LoopCounter 1 To 24 Step 1 LH1_Byte LoopCounter ASCII LH1a_Raw_In_Buff 1 1 LoopCounter If LoopCounter lt gt 24 LHa_CHECKSUM LHa_CHECKSUM LH1_Byte LoopCounter Endif Next LH1_CHECKSUM LH1_CHECKSUM AND amp B11111111 If LHa_CHECKSUM lt gt LH1_Byte LoopCounter Then LHa_Serial_Error TRUE Endif If LHa_Serial_Error TRUE Then Call LH1_Error_State Else For LH1 Byte 1 BIT o Status Output If LH1_Byte 1 AND amp B00000001 lt gt o Then LH1_Status_Output Fail Else LHa_Status_Output OK Endif BIT 1 Ice Output If LH1_Byte 1 AND amp Booooo010 lt gt o Then LHa_Ice_Output Ice Else LHa_Ice_Output No Ice Endlf BIT 2 Probe Heater State If LH1_Byte 1 AND amp Booooo100 lt gt o Then LH1_Probe_Heater_State On Else LH1_Probe_Heater_State Off Endif o871LH1 Bytes 2 and 3 are MSO Frequency count Calculate Frequency from the count as follows LH1_MSO_Frequency 774060000 LH1_Byte 2 lt lt 8 LH1_Byte 3 15 0871LH1 Freezing Rain Sensor 16 Byte 4 is the ERRSTAT1 If LHa_Byte 4 AND amp B1 lt gt o Then LH1_ERR_PWR_INT_TIMER FAIL Else LH1_ERR_PWR_I
30. nd detailed information on types and quantities of each annunciated failure This information is used by Rosemount Aerospace to confirm and repair failures reported by the end user and also to collect MTBF data Each time the Serial EEPROM is written a checksum is computed and written Each time the Serial EEPROM is read a checksum is computed and compared to the stored value B1 4 Probe Oscillator The probe oscillator is the electronic control portion of the magnetostrictive oscillator MSO used to sense and detect ice This circuit provides the drive and feedback of the ice sensing probe The circuit drives the probe at a nominal 40kHz and converts the feedback into a CMOS compatible square wave that is measured by the microcontroller As ice accretes on the probe the frequency decreases and it is this frequency change that the microcontroller annunciates in the form of Ice Signal 1 B1 5 Heater Control The heater control turns the probe heater on and off as commanded by the microcontroller and monitors the actual heater state ON or OFF for verification by the microcontroller Two outputs are required from the microcontroller to turn on the heater This minimizes the possibility of an unintended heater ON condition The heater control also monitors the state of the heater and provides feedback to the microcontroller so that it can be determined whether the heater is on or off Appendix B Freezing Rain Sensor B1 6 Drive Coil
31. ng for Discrete Output 7 9 2 0871LH1CBL L Wiring for RS422 OUtput iiiriiiee eine 8 10 Program Examples eneen n rererere rreren 9 10 1 CR1000 Example Discrete Outputs sssssssssssssrsrrsrrssssssssrsssrsririninnnnnnnsnsnsnernrn 9 10 2 CR23X Example Discrete Outputs 0 cesseesssessseesseecsteessteesseeseteessteesneeenses 11 10 3 CR1000 Example RS422 Outputs iu cei 12 Figures 1 MSO Circuit Sectional View sessssssesssseesssessssessssesssseesssseersseersseersnseessneessnse 2 2 MSO Circuit SCHEMA TC iasi iieiea anini ani naai iranta savy 3 Be YA Sa VA Kai Ka irisa aN cute aoa EEEa E DEE iii 5 A MOU NE AA E RA 6 5 General Hook up Diagram uiii ii 8 B1 Functional Block Diagram 0 eessessseessteeceeesseessteceseessneesneessteessteesneesateeeatees B 1 Tables 1 0871LH1 Connector PIN Ul eric 4 2 Datalogger COMMECtIONS sceessesssseecstecstessstessseesstecestessneesseecsseessneesueesateesstersneesnteesaees 7 3 Power Connections to Terminal EXpander uriii ini 7 4 Datalogger Connections assisia ismerni raer ainiti aeinn 8 5 Power Connections to Terminal Expamdet sscesssesssescsesseesstesseeseesnteessee 9 6 SCTLOGoNNECtONS staan a iii iii 9 A 1 BIT Informatio Hie ii nannan anaha han A 2 A 2 Serial String FORM ti ii A 5 B 1 0871LH1 Ice Detector Qualification Capabilities eee B 4 B 2 Input Output Pin Designations eessessseecssessseesste
32. nsing probe again to the point where the MSO frequency decreases by 130 Hz the sensor de ices itself again This cyclic process is repeated as long as the freezing rain sensor remains in an icing environment The ice signal activates at 0 5 mm ice accretion and stays on for 60 seconds after the end of the icing encounter Specifically when the output is activated a 60 second timer is started Each time 0 5 mm forms on the probe the 60 second counter is reset In effect the output stays on for 60 seconds after the beginning of the last icing encounter The Status output indicates whether the freezing rain sensor is functioning correctly using tests that are described in more detail in following sections of this document Ultrasonic Vibrating Probe 40KHz Nominal N Driv il ve lt Magnet Feedback Coil L Probe Heater Termination Strut Heaters Figure 1 MSO Circuit Sectional View 10 METERS NODE PLATE FEEDBACK coL DRIVE GOL 4 Specifications Power Supply Operating Voltage Power Draw Temperature Operating Storage User Manual f MAGNETORESTRICTIVE OSCILLATION 40 000 Hz NI SPAN C THIN WALLED TUBE Figure 2 MSO Circuit Schematic 18 29 5 VDC 5W max at 24 VDC sensing mode 27W max at 24 VDC deicing mode 55 C to 71 C 65 C to 90 C Communication Outputs Discrete Outputs
33. oriented into the prevailing wind 4 Connect cable to 0871LH1 connector and secure cable to bracket with cable ties 5 Remove shipping cover and protective cap prior to powering on the unit User Manual 9 Wiring The wiring of the 0871LH1 will depend on the required communication outputs of your application If you require the use of the discrete outputs of the 0871LH1 then refer to Section 9 1 If you require the use of the RS 422 output then refer to Section 9 2 NOTE Please contact a Certified Electrician to properly install the C2673 power supply All electrical connections and housings must be installed by a Certified Electrician 9 1 0871LH1CBL L Wiring for Discrete Output Table 2 Datalogger Connections Pin Colour CR3000 CR1000 CRIOX CR510 F Ble c 1 Cl Sar Brown N C N C G G G G PowerReferene B Buk o c Case GND C svPowr SV SV Shield sa G G WARNING The 5VDC connection must be made to avoid damage to the 0871LH1 WARNING Isolate wires that are not connected as they will cause problems if shorted to ground Table 3 Power Connections to Terminal Expander Description Pin Colour Connection 24 VDC A Red V 24VDC Return B Black V 0871LH1 Freezing Rain Sensor Transformer pata TITOLI n De Fren 1 000 quiz a O vira bs eni u EEE DN maw Ie ES n we AA mmama i mir
34. rom the contents Each time critical data is written to the Serial EEPROM a checksum is computed and stored with the data e Resets due to unknown reasons such as reset from the watchdog timer are detected Initiated BIT will examine the RESET EEPROM input If the input is active the STATUS output will be set to FAIL and the ICE output and probe heater will be disabled This feature allows a factory technician to perform the MSO capacitor selection process without activation of the probe heater Activation of the Press to Test PTT input for greater than 100 ms also causes the ice detector to perform Initiated BIT The PTT input is ignored when the ice output is active After PTT is completed the correlation count is restored to its pre test value Initiated BIT is complete within 3 seconds of initial power up A 8 Correlation Counting The freezing rain sensor tracks the amount of ice accumulation on the probe during an icing encounter The correlation count is a value tracked by the freezing rain sensor that indicates the amount of ice that has accumulated on the probe during the icing encounter Each correlation count equals 0 25 mm 0 01 of ice The correlation count ranging from 0 to 255 indicates the number of times the MSO frequency decreases by 65 Hz during an icing encounter A decrease in frequency of 65 Hz correlates to an equivalent 0 25 mm of ice that would have formed on the ice detector probe neglecting the
35. terproofness DO 160C Cat W Fungus Resistance DO 160C Cat F Sand and Dust DO 160C Cat D Direct Lightning Strike DO 160C Cat 1A Software DO 178B used as a guideline B 4 Appendix B Freezing Rain Sensor B 3 Input Output Specification B3 1 Input Output Pin Designations Table B 2 Input Output Pin Designations Signal Name Connector Input or Definition Current Wire Pin Output Gauge 1 5 Amp Max at 28VDC POR Input 18 29 5 VDC 20 24VDC Return B Input o _ 20 Case Ground C Input Lai 20 RS 422 High D Output Per RS 422 Spec Per RS 422 Spec 20 24 RS 422 Low E Output Per RS 422 Spec Per RS 422 Spec 20 24 Ice F Output Ground Active 1 5V Max 0 5 50 mA 20 24 Open Inactive Status G Output Ground Active 1 5V Max 0 5 50 mA 20 24 Open Active Ice will be correctly detected between these voltages Proper probe de icing however is only guaranteed when input voltage is 24VDC or greater B 5 CAMPBELL SCIENTIFIC COMPANIES Campbell Scientific Inc CSI 815 West 1800 North Logan Utah 84321 UNITED STATES www campbellsci com e info campbellsci com Campbell Scientific Africa Pty Ltd CSAf PO Box 2450 Somerset West 7129 SOUTH AFRICA www csafrica co za e sales csafrica co za Campbell Scientific Australia Pty Ltd CSA PO Box 8108 Garbutt Post Shop QLD 4814 AUSTRALIA www campbellsci com au e info campbellsci com au Campbell Scienti
Download Pdf Manuals
Related Search