Campbell SR50A Series Product Manual
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Campbell SR50A Series Product Manual

Sonic ranging sensors
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Revision: 02/2020
Copyright © 2007 – 2020
Campbell Scientific, Inc.

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Summary of Contents for Campbell SR50A Series

  • Page 1 Revision: 02/2020 Copyright © 2007 – 2020 Campbell Scientific, Inc.
  • Page 2 Limited warranty “Products manufactured by CSI are warranted by CSI to be free from defects in materials and workmanship under normal use and service for twelve months from the date of shipment unless otherwise specified in the corresponding product manual. (Product manuals are available for review online at www.campbellsci.com.) Products not manufactured by CSI, but that are resold by CSI, are warranted only to the limits extended by the original manufacturer.
  • Page 3 Campbell Scientific reserves the right to refuse service on products that were exposed to contaminants that may cause health or safety concerns for our employees.
  • Page 4 Periodically (at least yearly) check electrical ground connections. WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR...

  • Page 5: Table Of Contents

    Table of contents 1. Introduction 2. Precautions 3. Initial inspection 4. QuickStart 5. Overview 6. Specifications 6.1 Integrated temperature sensor 7. Installation 7.1 Beam angle 7.2 Mounting height 7.2.1 Reference point 7.3 Mounting 7.4 Wiring 7.5 Programming 7.5.1 SDI-12 programming 7.5.2 RS-232 programming 7.5.3 RS-485 programming 8.
  • Page 6 Appendix C. RS-232 and RS-485 operation C.1 RS-232 wiring C.2 RS-485 operation C.3 RS-485 wiring for direct data logger connection C.4 RS-485 wiring using an MD485 C.5 RS-232 and RS-485 settings C.5.1 Baud rate setting C.5.2 Address C.5.3 Operational mode setting C.5.3.1 Measure in poll mode C.5.3.2 Auto measure auto output mode C.5.3.3 Auto measure polled output mode...
  • Page 7 E.1.10 Send data command (aD0! … aD9!) E.1.11 Continuous measurement command (aR0! … aR9!) E.1.12 Extended commands E.2 SDI-12 transparent mode E.2.1 Changing an SDI-12 address E.2.2 Changing an SDI-12 address — CR200(X) Series E.3 References Campbell Scientific regional offices Table of Contents - vi...

  • Page 8: Introduction

    1. Introduction The SR50A-series sonic ranging sensors provide a non-contact method for determining snow or water depth. They determine depth by emitting an ultrasonic pulse and then measuring the elapsed time between the emission and return of the pulse. An air temperature measurement is required to correct for variations of the speed of sound in air.

  • Page 9: Precautions

    FIGURE 1-1. SR50AT mounted to a crossarm with the temperature sensor housed in a RAD06 radiation shield NOTE: This manual provides information only for CRBasic data loggers. For retired Edlog data logger support, see an older manual at www.campbellsci.com/old-manuals. 2. Precautions READ AND UNDERSTAND the Safety (p.

  • Page 10: Initial Inspection

    3. Initial inspection Upon receipt of the sensor, inspect the packaging for any signs of shipping damage and, if found, report the damage to the carrier in accordance with policy. The contents of the package should also be inspected and a claim filed if any shipping related damage is discovered. 4.
  • Page 11 3. In the Available Sensors and Devices box, start typing 107 or find the 107 in the Sensors > Temperature folder. Double click the 107 Temperature Probe. Use the default of degree Celsius. 4. Click on the Wiring tab to see how the sensor is to be wired to the data logger. Click OK after wiring the sensor.
  • Page 12 5. In the Available Sensors and Devices box, start typing SR50A. You can also find the sensor in the Sensors > Miscellaneous Sensors > SR50/SR50A Sonic Ranging Sensor folder. Double-click the sensor model; the SR50A-EE is programmed the same as the SR50A. Data defaults to meters, which can be changed by clicking the Unit of measure box and selecting cm, ft, or in.
  • Page 13 7. Repeat steps five and six for other sensors. Click Next. 8. In Output Setup, type the scan rate, meaningful table names, and Data Output Storage Interval. Click Next. Because of the delays using SDI-12, Campbell Scientific recommends measurement scans of 10 seconds or more.

  • Page 14: Overview

    9. Select the output options. 10. Click Finish and save the program. Send the program to the data logger if the data logger is connected to the computer. 11. If the sensor is connected to the data logger, check the output of the sensor in the data display in LoggerNet, RTDAQ, PC400, or PC200W to make sure it is making reasonable measurements.
  • Page 15 SDI-12, RS-232, and RS-485 output options are available for measuring the SR50A. The SR50A is factory configured as an SDI-12 sensor (address 0) because Campbell Scientific data loggers typically use the SDI-12 format. To use the RS-232 or RS-485 format, three jumpers inside the...

  • Page 16: Specifications

    6. Specifications Power requirements: 9 to 18 VDC Quiescent power consumption (no heater) SDI-12 mode: < 1.0 mA RS-232/RS-485 modes: < 1.25 mA (≤ 9600 bps), < 2.0 mA (> 9600 bps) Active power consumption (no heater): 250 mA typical Measurement time: Less than 1.0 s typical for RS-232 or RS-485 measurements 1.2 s typical for SDI-12 measurements Selectable outputs: SDI-12 (version 1.3)

  • Page 17: Integrated Temperature Sensor

    Sensor length: 10.1 cm (4 in) Sensor diameter: 7.6 cm (3 in) Sensor weight (no cable) Standard aluminum chassis: 0.4 kg (0.88 lb) Type III aluminum chassis: 0.36 kg (0.80 lb) Cable weight (15 ft): 0.25 kg (0.55 lb) IP rating Electrical housing: IP67 Transducer:...

  • Page 18: Beam Angle

    7.1 Beam angle When mounting the SR50A, the beam angle needs to be considered. Mount the SR50A perpendicular to the intended target surface. The SR50A has a beam angle of approximately 30 degrees. This means that objects outside this 30-degree beam will not be detected nor interfere with the intended target.

  • Page 19: Reference Point

    7.2.1 Reference point The front grill on the ultrasonic transducer is used for the reference for the distance values. Because of the difficulty of measuring from the grill, most users measure the distance from the target to the outer edge of the plastic transducer housing (FIGURE 7-2 (p.
  • Page 20 FIGURE 7-3. Two views of the crossarm installation using the SR50A mounting kit FIGURE 7-4. SR50A mounting stem SR50A-Series Sonic Ranging Sensors...

  • Page 21: Wiring

    FIGURE 7-5. SR50AT mounted to a crossarm using the mounting stem and a 1-inch-by-1- inch Nu-Rail fitting with the temperature sensor housed in a RAD06 radiation shield 7.4 Wiring Table 7-1 (p. 14) provides wiring information when using the SDI-12 output. Refer to RS-232 and RS-485 operation (p.

  • Page 22: Programming

    7.5 Programming Short Cut is the best source for up-to-date programming code for Campbell Scientific data loggers. If your data acquisition requirements are simple, you can probably create and maintain a data logger program exclusively with Short Cut. If your data acquisition needs are more complex, the files that Short Cut creates are a great source for programming code to start a new program or add to an existing custom program.

  • Page 23: Rs-232 Programming

    Split out digital count value from the input string. 7.5.3 RS-485 programming The RS-485 output can be directly read by a CR6-series and CR1000X-series. Other Campbell Scientific data loggers can use an MD485 multidrop interface to read the RS-485 output. Refer to the MD485 manual for information about using the MD485.

  • Page 24: Operation

    Programming for RS-485 output uses the same instructions as the RS-232 output (Table 7-2 16)). Refer to RS-232 and RS-485 operation (p. 31) for detailed information about using the RS- 485 output. Downloadable example programs for using the RS-485 output are available at www.campbellsci.com/downloads/sr50a-example-programs www.campbellsci.com/downloads/sr50at-example-programs.

  • Page 25: Temperature Compensation

    Table 8-1: Quality number description Quality number range Quality range description Not able to read distance 152 to 210 Good measurement quality numbers 210 to 300 Reduced echo signal strength 300 to 600 High measurement uncertainty Although not necessary, quality numbers provide useful information such as surface density in snow monitoring applications.

  • Page 26: Sdi-12 Measurements

    FIGURE 8-1. SR50AT-CBL For the RS-232 and RS-485 modes, temperature correction using the integrated temperature probe measurement is applied to the readings by default. For the SDI-12 output mode, the data logger must include a measurement command that outputs temperature. Otherwise, the temperature correction will not be applied.
  • Page 27 NOTE: The SR50A needs to be powered for 1.5 s before it can receive an SDI-12 command. The different commands are entered as options in the SDI-12 recorder instruction. The user has the option to output the distance to target in either meters or feet, or to include the measurement quality numbers.
  • Page 28 Table 8-2: SDI-12 commands SDI-12 Command Values returned command function/description Concurrent Measurement Commands with Output is the same as aM, aCC! aCCn! Checksum aM1-aM8 Checksum is added See aM and aM1-aM8 aD0! Send Data Dependent upon command sent S1, S2, V, WD S1 = Operating System Signature Verification Command S2 = BootRom Signature...
  • Page 29 Table 8-2: SDI-12 commands SDI-12 Command Values returned command function/description Returns the distance to ground setting in the aR1! SR50AT. The units returned are in inches. Returns the temperature sent to the SR50AT for internal temperature compensation. This aR2! value remains the same unless power is cycled or a new temperature values is sent.

  • Page 30: Measuring Multiple Sdi-12 Sensors

    Disassembly is required to inspect or replace the desiccant, and to change the transducer and the option jumpers. CAUTION: Before proceeding with any maintenance, always retrieve the data first. Campbell Scientific also recommends saving the data logger program. SR50A-Series Sonic Ranging Sensors...
  • Page 31 CAUTION: Always disconnect the SR50A from the data logger or the connector before disassembling. FIGURE 9-1. Disconnect Cable from Sensor FIGURE 9-2. Remove six screws from the transducer housing SR50A-Series Sonic Ranging Sensors...
  • Page 32 FIGURE 9-3. Remove transducer housing and disconnect wires FIGURE 9-4. Location of desiccant in transducer housing assembly SR50A-Series Sonic Ranging Sensors...
  • Page 33 FIGURE 9-5. Remove and replace desiccant FIGURE 9-6. Remove the two flat Phillips screws to expose the PCB Carefully reassemble in reverse order. SR50A-Series Sonic Ranging Sensors...

  • Page 34: Data Interpretation

    9.2 Data interpretation Although not common, the SR50A can output invalid reading indicators if unable to obtain a measurement. For distance to target values, a 0.0 reading is usually output. For snow depth outputs, the error indicator value is -999. An invalid temperature reading is also indicated by a -999 reading.
  • Page 35 Table 9-1: Data filtering example If 11 consecutive values are as After being sorted from follows for snow depth low to high 0.37 0.33 0.28 0.34 0.36 0.35 0.10 (high error value) 0.36 0.33 0.37 0.32 The best course of action would be to ignore the five lowest values and take the sixth value (0.33).

  • Page 36: Appendix A. Importing Short Cut Code Into Crbasic Editor

    Appendix A. Importing Short Cut code into CRBasic Editor Short Cut creates a .DEF file that contains wiring information and a program file that can be imported into the CRBasic Editor. By default, these files reside in the C:\campbellsci\SCWin folder. Import Short Cut program file and wiring information into CRBasic Editor: 1.

  • Page 37: Appendix B. Jumper Settings

    Appendix B. Jumper settings FIGURE B-1 (p. 30) shows the jumper locations of the SR50A. FIGURE B-1. Jumper settings The SR50A can be configured with either SDI-12, RS-232 or RS-485 communications. Shunt jumpers can be located on any of the three sets of communication selection headers. Only place the three jumpers on one group at a time.

  • Page 38: Appendix C. Rs-232 And Rs-485 Operation

    Appendix C. RS-232 and RS-485 operation The SR50A sensor comes from the factory with the internal jumpers set to SDI-12 mode. To use the SR50A in the RS-232 or RS-485 mode of operation, the jumpers need to be set as outlined in Jumper settings (p.
  • Page 39 Interface with Hood and Hardware Kit, DB9 Female to Terminal Block Pin Assignment Pins used for RS-232 communication in bold lettering. FIGURE C-1. RS-232 DB9 Connector Description Table C-2: SR50A RS-232 interface wiring SR50A wire color Function Wiring location +12 VDC power Power source (data logger: 12V) System ground and/or Black...

  • Page 40: Rs-485 Operation

    The CR6 and CR1000X data loggers can read the SR50A output without an interface such as the MD485. For other Campbell Scientific data loggers, the MD485 interface is required to connect one or more SR50A sensors. The RS-485 mode is useful for sensors that require cable lengths that exceed the limits of either RS-232 or SDI-12 communications.

  • Page 41: Rs-485 Wiring Using An Md485

    C.4 RS-485 wiring using an MD485 Table C-4 (p. 34) and FIGURE C-2 (p. 34) show the wiring for the SR50A when using an MD485 Multidrop Interface to read the RS-485 output. Table C-4: Connections to MD485A Multidrop Interface Color Function Connection System ground and/or RS-232 receiver ground...

  • Page 42: Rs-232 And Rs-485 Settings

    C.5 RS-232 and RS-485 settings Once the jumpers are set for RS-232 operation, Device Configuration Utility is used to change factory defaults or existing settings. Use a terminal program that allows local echo. The following settings apply to Device Configuration Utility or any program used for communications. Baud rate: Current SR50A setting (see NOTE) Data bits:...
  • Page 43 FIGURE C-3. Initial terminal window in Device Configuration Utility To enter Setup mode, type setup in the terminal window and press the Enter key. The word setup and all options in the setup menu are not case sensitive. The SR50A should respond with the setup menu shown in FIGURE C-4 (p.
  • Page 44 FIGURE C-4. SR50A Setup Menu Table C-5 (p. 37) summarizes the settings that can be changed using the SR50A RS-232 or RS-485 operating modes. Recommended changes are shown in parenthesis. Table C-5: RS-232 and RS-485 settings Setting description Options Default value 1200 4800 Baud rate...

  • Page 45: Baud Rate Setting

    Table C-5: RS-232 and RS-485 settings Setting description Options Default value Distance to target or depth Distance to target Distance to target output depth Distance to ground Decimal value in meters Seconds Measurement interval units Minutes Seconds Hours Measurement interval value Integer 1-255 Meters Centimeters...

  • Page 46: Address

    C.5.2 Address The factory default address is 33. For RS-232 applications, use the factory default address. For RS- 485 operation, multiple sensors can be polled individually if different addresses are assigned. C.5.3 Operational mode setting Three different operational mode settings are available on the SR50A. Overall system design and desired performance determine which mode to select.

  • Page 47: Distance To Target Or Depth

    The main advantage of this operating mode is that the receiving device will only have to wait 100 ms for the data instead of 1 second. This configuration is also more conducive to a multidrop RS-485 system where individual sensors do not transmit until they are addressed. C.5.4 Distance to target or depth The SR50A can output either distance to target values or calculate snow depth values.

  • Page 48: Quality Output

    range from 1 to 255. The units used for the value is set by the Measurement Interval Units. C.5.8 Quality output The SR50A quality numbers can be optionally included in the data output string. The Quality Output setting can be set to ON or OFF. C.5.9 Diagnostics output The SR50A diagnostics numbers can be optionally included in the data output string.

  • Page 49: Rs-232/Rs-485 Data Output Format

    “tAA;-5.5<CR>” – where AA is a two-character address and set from the factory to 33 and –5.5 is the temperature in degrees C “t33;tt.ttt<CR>” – Temperature command with factory address of 33 and a temperature value in Celsius. C.7 RS-232/RS-485 data output format The measurement output string for the SR50A is as follows: <STX>aa;D.DDD;QQQ;TT.TT;VVVVV;CC<CR><LF><ETX>...
  • Page 50 VVVVV This is the diagnostic output value. Each digit represents a pass or a fail on a diagnostic test. XVVVV If X is a 1, then the ROM Memory has passed the signature test. VXVVV If X is a 1, then no watchdog errors have occurred. VVXXX The three digits XXX are for factory use and should always read 111.
  • Page 51 These two characters are the serial address of the sensor. The default is 33. Note this is two ASCII characters of 0x33 in hexidecimal or 51 in decimal. SSSSS This is the serial number of the sensor. This is the hardware version of the sensor. This is the operating system version of the sensor.

  • Page 52: Appendix D. Sr50Ah Heater Operation

    Always use the heater option wired to switched 12 VDC source. For battery-operated solar- powered sites, Campbell Scientific recommends that the heater power be turned off when icing conditions are not occurring to reduce power requirements. The heater power must be turned off when operating at temperatures of 25 °C or more.

  • Page 53: Heating Cable Requirements

    D.1.1 Heating cable requirements Type: 2 conductor (twisted pair), shielded Diameter: 4 to 6 mm (0.16 to 0.24 in) Recommended gage:  22 AWG for lengths < 30 m (100 ft) FIGURE D-1. SR50AH heater option D.2 Heater maintenance Most of the maintenance is the same as the maintenance for the standard SR50A Maintenance and troubleshooting (p.
  • Page 54 1. Remove the six Phillips screws on the outermost hole pattern. NOTE: The screws used on the SR50A have changed from the slotted type to Phillips. 2. Separate the housing from the sensor body and disconnect the connector from the transducer to the main sensor body.
  • Page 55 3. To replace the desiccant, remove the desiccant holder plate with the Phillips 4-40 screw. Cutting the tie strap will allow the old packets to be removed for replacement. During reassembly, ensure that the desiccant does not come in contact with the metal backing of the transducer.
  • Page 56 5. Remove the three screws from the innermost hole pattern as shown. 6. Replace the transducer assembly and the second O-ring that seats under the transducer assembly. 7. Reassemble the sensor in the reverse order. Please observe the orientation of the parts, wiring, and desiccant.

  • Page 57: Appendix E. Sdi-12 Sensor Support

    SDI-12, Serial Data Interface at 1200 baud, is a protocol developed to simplify sensor and data logger compatibility. Only three wires are necessary — serial data, ground, and 12 V. With unique addresses, multiple SDI-12 sensors can connect to a single SDI-12 terminal on a Campbell Scientific data logger.

  • Page 58: Acknowledge Active Command (A!)

    Table E-1: Campbell Scientific sensor SDI-12 command and response set Response Name Command aAb! Change Address b<CR><LF> Start Measurement atttn<CR><LF> aM1!...aM9! aMC! Start Measurement atttn <CR><LF> aMC1!...aMC9! and Request CRC Start Concurrent Measurement atttnn<CR><LF> aC1!...aC9! aCC! Start Concurrent Measurement atttnn<CR><LF> aCC1!...aCC9! and Request CRC a<values><CR><LF>...

  • Page 59: Start Verification Command (Av!)

    mmmmmm 6 characters specifying the sensor model 3 characters specifying the sensor version (operating system) Up to 13 optional characters used for a serial number or other specific xxx…xx sensor information that is not relevant for operation of the data logger Terminates the response <CR><LF>...

  • Page 60: Start Measurement Commands (Am!)

    E.1.6 Start measurement commands (aM!) A measurement is initiated with the M! command. The response to each command has the form atttn<CR><LF>, where a = sensor address ttt = time, in seconds, until measurement data is available. When the data is ready, the sensor notifies the data logger, and the data logger begins issuing D commands.
  • Page 61 nn = the number of values to be returned when one or more subsequent D commands are issued. See the following example. A data logger has three sensors wired into terminal C1. The sensors are addresses X, Y, and Z. The data logger will issue the following commands and receive the following responses: Table E-3: Example aC! sequence The data logger makes a request to sensor X to start...

  • Page 62: Start Measurement Commands With Cyclic Redundancy Check (Amc! And Acc!)

    Table E-3: Example aC! sequence Ten seconds later, after a total of 40 seconds have passed, the data logger starts the process of YD0! collecting data from sensor Y by issuing the first D command. The sensor immediately responds with the sensor Y+1+2+3+4+5+6<CR><LF>...

  • Page 63: Continuous Measurement Command (Ar0

    characters of data in response to a D command that follows an M! or MC! command. A sensor may return up to 75 characters of data in response to a D command that follows a C! or CC! command. Data values are separated by plus or minus signs. Command: aD0! (aD1! …...

  • Page 64: Changing An Sdi-12 Address

    Transparent mode is entered while the computer is communicating with the data logger through a terminal emulator program. It is accessed through Campbell Scientific data logger support software or other terminal emulator programs. Data logger keyboards and displays cannot be used.

  • Page 65: Changing An Sdi-12 Address - Cr200(X) Series

    exited. In that case, simply type SDI12 again, press Enter, and type the correct control port number when prompted. 10. To change the SDI-12 address, type aAb!, where a is the current address from the previous step and b is the new address (see FIGURE E-1 (p.

  • Page 66: References

    3. Under Select Device, located in the lower left side of the window, select the CR200Series station. 4. Click Open Terminal. 5. Select All Caps Mode. 6. Press Enter until the data logger responds with the CR2XX> prompt. 7. Type SDI12 and press Enter. 8.

  • Page 67: Campbell Scientific Regional Offices

    Australia France Thailand Location: Garbutt, QLD Australia Location: Vincennes, France Location: Bangkok, Thailand Phone: 61.7.4401.7700 Phone: 0033.0.1.56.45.15.20 Phone: 66.2.719.3399 Email: info@campbellsci.com.au Email: info@campbellsci.fr Email: info@campbellsci.asia Website: www.campbellsci.com.au Website: www.campbellsci.fr Website: www.campbellsci.asia Brazil Germany Location: São Paulo, SP Brazil Location: Bremen, Germany Location: Shepshed, Loughborough, UK Phone:...

This manual is also suitable for:

Sr50aSr50-eeSr50ahSr50atSr50athSr50a-ee

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