Campbell SR50 Instruction Manual
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Campbell SR50 Instruction Manual

Sonic ranging sensor
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SR50 Sonic Ranging Sensor
Revision: 1/07
C o p y r i g h t
©
1 9 9 5 - 2 0 0 7
C a m p b e l l
S c i e n t i f i c ,
I n c .

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  • Page 1 SR50 Sonic Ranging Sensor Revision: 1/07 C o p y r i g h t © 1 9 9 5 - 2 0 0 7 C a m p b e l l S c i e n t i f i c ,...
  • Page 2 Warranty and Assistance The SR50 SONIC RANGING SENSOR is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or...

  • Page 3: Table Of Contents

    6. Maintenance ...............23 7. Assembly/Disassembly Procedures ......24 Figures 1. SDI-12 Wiring ..................5 2. SR50 Wiring for CR10(X) SDI-12 Example ..........6 3. Pulse Train Wiring..................11 4. SR50 Wiring for 21X Pulse Example .............12 5. SR50 Cone Angle ...................20 6a. SR50 Tripod Mount ................20 6b.
  • Page 4 SR50 Sonic Ranging Sensor Table of Contents Tables 1. SR50 SDI-12 Command List ..............9 2. Address Jumper Settings for Pulse Train and ASCII Outputs....19 Appendices A. Making Concurrent Measurements with the SR50 ..A-1...
  • Page 5 Procedures” on page 24 of the manual. Damage may occur to the transducer wires if the transducer assembly is not carefully orientated when fastening to the SR50 housing. The transducer assembly should be positioned in such a way that the wires are sure to remain within the inside wall of the housing.
  • Page 6 This is a blank page.

  • Page 7: Sr50 Specifications

    SR50 Sonic Ranging Sensor 1. SR50 Specifications Power Requirements: 9-16 VOLTS D.C. Power Consumption: 2 mA (Quiescent) 250 mA (Measurement Peak) Measurement Time: 0.6 seconds typical 3.0 seconds max. Output: SDI-12 (version 1.2) Serial ASCII - 300 and 1200 Baud TTL or RS-232...

  • Page 8: Introduction

    A simple calculation is applied to initial readings for this purpose. The SR50 is capable of picking up small targets or targets that are highly absorptive to sound--such as low density snow. The SR50 can measure multiple targets and it makes use of a unique echo processing algorithm to help ensure measurement reliability.

  • Page 9: Operation (General)

    22°. The closest object to the sensor will be detected if it is within this field of view. If a target is in motion, the SR50 may reject a reading if the target distance changes at a rate of 4 centimeters per second or more.

  • Page 10: Sdi-12 Operation

    SDI-12 sensors (CR10’s with the correct PROM can do SDI-12). The SR50 can be set to one of ten addresses (0 to 9) which allows up to ten sensors to be connected to a single digital I/O channel (control port) of an SDI-12 datalogger.

  • Page 11: Sdi-12 Wiring

    "8" command ensures that the sensor will complete the measurement within a one second period by disabling retries. If the SR50 is unable to detect a proper echo for a measurement, the sensor will return a zero value for the distance to target value. When the multiple...

  • Page 12: Sdi-12 Cr10(X) Program Example

    FIGURE 2. SR50 Wiring for CR10(X) SDI-12 Example 3.2 SDI-12 CR10(X) Program Example In this example, the SR50 is mounted 2 meters above the ground. Snow depth and a quality of measurement number is the desired output. This program uses Instruction 105 (refer to the CR10(X) manual for details on the SDI-12 Recorder Instruction) to obtain a distance measurement from the SR50.
  • Page 13 Offset ; This converts the value to degrees Kelvin. ; Measure the SR50 using code ‘1’ for parameter 2. This will cause the SR50 to measure the distance to target (in meters) and provide a measurement quality number. 2: SDI-12 Recorder (P105)
  • Page 14 SR50 Sonic Ranging Sensor 6: Z=X*Y (P36) 1: 2 X Loc [[ DEPTH ] 2: 5 Y Loc [ MULT 3: 2 Z Loc [[ DEPTH ] 7: Z=X+F (P34) 1: 2 X Loc [ DEPTH ] 2: 2.0 ; <<<<<<<<<< Insert the distance from sensor to bare ground...

  • Page 15: Sr50 Sdi-12 Command List

    Start Verification calculates NUMERIC SIGNATURE ROM Signature Send Identification 012CAMPBELLSR50 1.1 NOTE: There are 2 spaces between SR50 and 1.1 Concurrent Measurement* Concurrent Measurements* Same as M – M8 Where a = address of SDI-12 device. Where n = numbers 1 to 8.

  • Page 16: Pulse Train Output

    +5 Volts. The pulse width should be a minimum of 5 ms and a maximum of 250 ms in width. When the SR50 detects that the Sensor Enable Line is high, it makes a measurement. When complete, the SR50 outputs the appropriate pulse train on the SDI-12 Bus.

  • Page 17: Pulse Train Wiring

    SR50 Sonic Ranging Sensor 3.3.1 Pulse Training Wiring Datalogger Color Function Connection Black Ground Ground (G) +12V +12V Green Data Bus Pulse Channel White Sensor Enable Control Port Clear Shield Ground (G) FIGURE 3. Pulse Train Wiring CAUTION The order in which the connections are made is critical.

  • Page 18: Two 21X Program Examples For Pulse Train Output

    The programming examples assume that the sensor is mounted 2 meters above the ground and the desired output is snow depth in meters. In these examples a 21X micrologger is used to read the SR50 with the pulse train option. The number of pulses are counted on Pulse channel 1.
  • Page 19 Set Low 2: 1 Port Number The P3 instruction counts the pulse train being transmitted from the SR50. Distance-to-surface will automatically be reset to 0.00 after the distance is calculated and stored for later processing and output. 4: Pulse (P3)
  • Page 20 SR50 Sonic Ranging Sensor 8: Z=SQRT(X) (P39) 1: 24 X Loc [ ATempComp ] 2: 24 Z Loc [ ATempComp ] 9: Z=X*Y (P36) 1: 21 X Loc [ Dis2Surf ] 2: 24 Y Loc [ ATempComp ] 3: 21...
  • Page 21 3.4.2 Pulse Train Programming Example 2 Example 2 will measure every execution interval. This program will measure the SR50 when Flag 1 is set high, which can be done manually and/or at a specified interval. All instructions above those that define the Output Interval must remain together.
  • Page 22 SR50 Sonic Ranging Sensor If Flag 2 is high, compute the air temperature compensation factor and correct the distance-to-surface measurement for air temperature (see Formula 1). 3: If Flag/Port (P91) 1: 12 Do if Flag 2 is High 2: 30...
  • Page 23 SR50 Sonic Ranging Sensor Parameter 2 of P92 determines how often to measure. 12: If time is (P92) 1: 0 Minutes into a 2: 15 Minute Interval 3: 11 Set Flag 1 High 13: If Flag/Port (P91) 1: 11 Do if Flag 1 is High...

  • Page 24: Ascii Output

    Sensor Enable Line high to +5 Volts. The pulse width should be a minimum of 5 ms and a maximum of 250 ms. Once the SR50 detects the Sensor Enable Line has gone high, it makes a measurement. When the measurement is finished, the SR50 outputs the appropriate serial data.

  • Page 25: Sensor Mounting And Installation

    4. Sensor Mounting and Installation When mounting the SR50, the sensor's beam angle needs to be considered (see Figure 5). It is important to remember that the SR50 has a beam angle of approximately 22 degrees. This means that no objects should obstruct the intended target within this 22 degree beam.

  • Page 26: Sr50 Cone Angle

    The SR50’s mounting stem also has 1” pipe thread to accommodate other threaded installation options. Campbell Scientific offers hardware that enables mounting the SR50 to towers (see Figures 6a and 6b) or a vertical pipe with 0.75” to 1.25” diameter.

  • Page 27: 6B. Sr50 Tower Mount

    4 cm/sec or more may cause the SR50 to reject a reading and output a zero as the distance to target. If vibration is the concern, it could be reduced by using guy wires on the mounting structure.

  • Page 28: Data Interpretation

    One such example is snow of extremely low density. In this situation, the surface may not reflect enough sound for the sensor to detect. The SR50 will output zero for the distance to target or a single pulse in the pulse output mode.

  • Page 29: Measuring Snow Depth

    5.1 Measuring Snow Depth The SR50 measures the distance to the surface that it is pointed at. The sensor is mounted above and perpendicular to the surface. To obtain snow depth, the distance to snow must be subtracted from the distance to ground. The instruction that measures the SR50 has a negative multiplier, yielding a negative distance to surface measurement.

  • Page 30: Assembly/Disassembly Procedures

    SR50 Sonic Ranging Sensor 7. Assembly/Disassembly Procedures It is important to follow these instructions to disassemble the SR50. Disassembly is required to change the Address/Option jumpers and to inspect or replace the desiccant. There are two small packages of desiccant inside the transducer housing as well as desiccant inside the electronics enclosure (Refer to Figure 8).
  • Page 31 SR50 in the reverse order. To obtain access to the address/option jumpers, unscrew the cylinder of the SR50 from the lid and slide the cylinder off. The internal jumpers are now exposed to set the address or to change the sensor's output options.

  • Page 32: Sr50 Stuffing Chart/Jumper Settings

    .0033 F 1000pf 1.5KE20CA 1000pf 0.1 F 1.0mH LT1086-5 LM2901N 1000pf 68HC71103 IN4001 .047 F 20 1/2W IRFD113 0.01 F 4.7K 2N3004 220 F 0.1 F ADDRESS/OPTION JUMPERS Address 15 for factory use only FIGURE 8: SR50 Stuffing Chart/Jumper Settings...
  • Page 33 (use option code “ # -- “ where # is a number 0-8; see Table 1). To Determine SR50 OS Version: To determine the version of software in the SR50, insert ‘10’ in parameter 2 of the P105 SDI-RECORDER instruction (SDI-12 command “aI” where a = address).
  • Page 34 Reset counter. Example Program: In this example, an SR50 is mounted 2 meters above the ground. Snow depth and measurement quality numbers are the desired output. This program uses Instruction 105 (refer to Section 9 in the CR10X manual for details on P105 SDI-Recorder Instruction) to obtain a distance measurement from the SR50.
  • Page 35 Appendix A. Modifying the Non-Volatile Memory 4: If (X<=>F) (P89) 1: 3 X Loc [ Raw_Dist ] 2: 3 >= 3: -1000 4: 30 Then Do 5: Z=X (P31) 1: 3 X Loc [ Raw_Dist ] 2: 8 Z Loc [ DEPTH 6: Z=X (P31) 1: 4 X Loc [ Raw_Qual ]...
  • Page 36 Appendix A. Making Concurrent Measurements with the SR50 14: End (P95) 15: End (P95) ; Apply air temperature correction to the reading... 16: Z=F (P30) 1: 273.15 2: 0 Exponent of 10 3: 6 Z Loc [ REF_TEMP ] 17: Z=X/Y (P38)
  • Page 37 This is a blank page.
  • Page 38 Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA)

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