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Sequoia LISST-ABS User Manual

Acoustic backscatter sensor
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LISST-ABS
Acoustic Backscatter Sensor
User's Manual
Version 1.4
February 2017
Sequoia Scientific, Inc.
2700 Richards Road Suite 107
Bellevue, WA, 98005, USA
Phone: +1 425-641-0944; Fax: +1 425-643-0595
support@SequoiaSci.com; www.SequoiaSci.com

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  • Page 1 LISST-ABS Acoustic Backscatter Sensor User’s Manual Version 1.4 February 2017 Sequoia Scientific, Inc. 2700 Richards Road Suite 107 Bellevue, WA, 98005, USA Phone: +1 425-641-0944; Fax: +1 425-643-0595 support@SequoiaSci.com; www.SequoiaSci.com...
  • Page 3 Distributor, or Sequoia if the instrument was purchased directly from Sequoia. Please be sure to include the instrument serial number with any correspondence. A list of local Sequoia distributors can be found at our website http://www.sequoiasci.com/about/contact/distributors Sequoia Scientific, Inc. can be reached at support@sequoiasci.com...

  • Page 4: Table Of Contents

    ..................17 PERATIONS VIA SOFTWARE 2.6 F ..................27 IELD EPLOYMENT UGGESTIONS APPENDIX A: LISST-ABS CABLE WIRING AND CONNECTOR PINOUTS ......28 APPENDIX B: CONVERTING UNCALIBRATED CONCENTRATION TO CONCENTRATION 30 APPENDIX C: HOW THE LISST-ABS WORKS ................31 WARRANTY ..........................34...

  • Page 5: Section 1: Quick Start

    The Uncalibrated Concentration is converted to Concentration using standard calibration procedures such as used for turbidity sensors. For more details see Appendix B and Appendix C. The LISST-ABS is shipped ready for use. It takes just 3 easy steps to start seeing some real measurements. Step 1:...
  • Page 6 You can now start the LISST-ABS software to see the values in real time. You can also use the software to log data. Below is a screen shot of the software while data is being logged to text file. More details on the operation of the software can be found in Section 2.5.

  • Page 7: Section 2: Instructions

    LISST-ABS will output an Uncalibrated Concentration value of -999. When the LISST-ABS is powered up the green LED on the endcap will start to blink at about once per second. This indicates the instrument is powered up and operating normally.

  • Page 8: Sdi-12 Operations

    The LISST-ABS is compatible with SDI-12 protocol version 1.3. 2.2 SDI-12 Operations This section is divided into two parts, Connecting to your datalogger and SDI-12 command summary. SDI-12 only requires three wires. Power, Ground and Data. SDI-12 Connections Appendix A includes detailed descriptions of the use of the individual pins of the 8-pin connector on the LISST-ABS.
  • Page 9 LISST-ABS SDI-12 Command Summary Command Name Command Code Notes Address Query Request address of single sensor on bus Acknowledge Active Request response from sensor at address a Change Address aAb! Change address of sensor at address a to b Send Identification...
  • Page 10 LISST-ABS SDI-12 Command Details Basic Command Set Address Query Syntax: ?! Description: Request address of single sensor on bus. Note: sensor must be the only sensor on the bus or multiple instruments will respond simultaneously. Example: Command: ?! Response: 0...
  • Page 11 Response: 3+1234.56 (responds with Uncalibrated Concentration, C Note: in response to certain commands, the data returned after a D command may have a CRC value appended to it. Since the LISST-ABS has only one output only the aD0! command is required.
  • Page 12 Continuous Measurements Syntax: aR! Description: Not supported. The LISST-ABS is not a continuous measurement device. No data will be returned. The response to this command is below. Example: Command: 3R! (request continuous measurement) Response: 3 (responds with address of sensor)
  • Page 13 In order to obtain the most accurate results it is recommended LISST-ABS and SDI-12 that the LISST-ABS collect a 30 second or longer average. The Best practices LISST-ABS is more sensitive to larger particles and the sample volume is smaller.

  • Page 14: Rs232 Output Operations

    ABS Transmit wire to the datalogger receive input and the Blue ABS Receive wire to the datalogger transmit output. The LISST-ABS uses a baud rate of 9600 with 8 data bits, one stop bit, no parity, and no flow control.
  • Page 15 LISST-ABS as it is output. As described below in the recommended sampling procedure, the instrument should be allow to output for 30 seconds after power up before measurements are recorded. There are also a set of commands that can be sent to the LISST-ABS to give more control of the flow of data.
  • Page 16 Take Sample and hold it Syntax: HS or hs or holdsample Description: Instrument makes a measurement and stores it in memory. The results are NOT sent to the RS-232 output. Only a LISST-ABS> prompt is returned. Example: Command: HS 30 Response: LISST-ABS>...
  • Page 17 Response: 1.23456E3 LISST-ABS> Return Return to Automatic Mode Syntax: return or exit Description: Returns the LISST-ABS to automatic mode where results are output to the RS232 every 1 second Example: Command: Exit Response: <delay of 1 second> 1.23456E3 <delay of 1 second>...
  • Page 18 LISST-ABS to record 60 measurements 1 second apart. Option 2: Issue GetSample commands to record 60 measurements 1 second apart. 3) Power down the LISST-ABS and wait till the next sample time. For suggestions on mounting, cleaning and maintenance please see Section 2.6.

  • Page 19: Analog Output Operations

    2.4 Analog Output The LISST-ABS also provides an analog output for use with Operations data acquisition systems that do not support RS232 or SDI-12 interfaces. Using the Analog Output requires four wires. Power, Power Ground, Signal and Signal Ground. The two grounds can be combined, but separating them provides the best accuracy.
  • Page 20 2) Record 60 measurements of the analog voltage 1 second apart. 3) Power down the LISST-ABS and wait till the next sample time. For suggestions on mounting, cleaning and maintenance please see Section 2.6.

  • Page 21: Usb Operations Via Pc Software

    .NET framework 4.0 or later installed on your computer. You can determine if the framework is installed on your computer by simply running the LISST-ABS installer. If the framework is missing, a warning message will appear: Should you receive this message, return to the USB card and run the ‘dotNetFx40_Client.exe’...
  • Page 22 Ensure the instrument is connected to the computer via the USB cable. Within a few seconds the software will find the instrument and begin displaying concentration values (default calibration factor of 1). The instrument serial number will also be displayed at the bottom left of the screen. The software will automatically start plotting the concentration as function of sample number.
  • Page 23 If the Sequoia USB cable is not available you can still use the software via any RS232 connection to the PC. You will need to power the instrument separately. See Appendix A for wiring instructions. Should you have more than one ABS instrument plugged into your computer, the software will interface with the first instrument it finds while searching your computer’s ports.
  • Page 24 Calibration The concentration displayed in the software will be incorrect until an accurate calibration factor is entered in the software (see Appendix B for an explanation of calibration constants). If you are only interested in viewing and logging uncalibrated concentration, you can skip this section. If you already have a calibration factor for your instrument, you can simply type it into the ‘Cal.
  • Page 25 If you elected to save the uncalibrated ABS values, a text file will be saved at the location you specified before starting the calibration. It will contain a header with calibration information, followed by the 100 uncalibrated ABS measurements used to calculate the new calibration factor.
  • Page 26 The header is followed by three columns of data: date, time, and concentration (mg/L). Data Plotting The LISST-ABS software automatically plots concentration as a function of sample number. Data shown in the plot is color coded to indicate what operation the software is preforming.
  • Page 27 being calibrated, data are plotted in red. Scaling of the y-axis is handled automatically by default. However, if you wish to lock the y-axis limits at a specific value, enter a number in the text box next to ‘Min’ or ‘Max’ in the ‘Plot Controls’...
  • Page 28 LISST-ABS software will automatically reconnect when the power or connection is reestablished. If the disconnection occurs while logging data, the logging will pause and resume automatically when the instrument is reconnected. Should one of the two error codes be produced by the ABS, a brief description of the problem will be shown.
  • Page 29 Settings/Tools Program settings and tools are accessed by clicking the gear icon in the lower right corner. This provides access to a terminal window, the users manual, and communication settings. The terminal window allows you communicate directly with the instrument. This can be useful for retriving information about your sensor or exploring the instruments serial communication features.
  • Page 30 Communication Settings allows you to disable the automatic port searching feature. If you know what port your LISST-ABS is connected to, you can specify the port in this window. This can be useful if you are on a computer with many ports, or have...

  • Page 31: Field Deployment Suggestions

    2.6 Field Deployment The mounting and orientation of the LISST-ABS is similar to Suggestions that of optical backscatter and turbidity sensor. suggestions below may help when determining how to mount or orientate the LISST-ABS The LISST-ABS measures backscatter from two cells at approximately 5 and 10 cm from the sensor head.

  • Page 32: Appendix A: Lisst-Abs Cable Wiring And Connector Pinouts

    This appendix details the configuration of the LISST-ABS connectors and cables so that it can be connected to the dataloggers. We will start at connector on the LISST-ABS and work toward the end of the long cable. Details of The endcap connector on the LISST-ABS is an Impulse MCBH8-M-P, wired Underwater as shown below.
  • Page 33 Sequoia offers cables for the LISST-ABS in lengths from 5 to 50 meters. These cables include an underwater connector is spliced to a longer cable which is terminated with a white plastic Molex connector. When purchasing the long cable multiple mating cables are provided for different datalogger connections.

  • Page 34: Appendix B: Converting Uncalibrated Concentration To Concentration

    C = Cu * Cal Factor Where CalConst is characteristic of a sediment size and type. All LISST-ABS instruments are calibrated using glass spheres between 63 and 90 microns. They are configured so that Cal Const = 1 for these particles.

  • Page 35: Appendix C: How The Lisst-Abs Works

    Appendix C: How the LISST-ABS works Basics The LISST-Acoustic Backscatter Sensor, LISST-ABS operates in a manner similar to radar. A short pulse of high-frequency sound is transmitted by a ceramic transducer (see Figure). The pulse travels outward, and its location at any time is at a distance equal to the product of speed of sound in water c, and time t after transmission, ct.
  • Page 36 To find the new calibration factor, we recommend using our provided Windows software. Prepare a mixture in a well-mixed chamber [Use of Sequoia's mixing chamber is strongly recommended]. Insert the instrument tip at the surface. Be sure to leave 15 cm gap between sensor and chamber bottom.

  • Page 37: Specifications

    Specifications: Technical: Mechanical and Electrical: • • Acoustic Frequency: 8 MHz Sensor Dia.: 2.00 in (5.08 cm) • • Sample Volume: 10 dia x 15 L (mm) (located Length: 13.25 in (33.65 cm) • 5.5 cm in front of sensor) Weight: 1 lb.

  • Page 38: Warranty

    Period”), any Product does not comply with the warranties set forth in 1(a) and 1(b) above, SEQUOIA will, at its option, either (a) repair the Product, (b) replace the Product, or (c) refund the purchase price paid by Customer to SEQUOIA for the Product;...
  • Page 39 SEQUOIA's liability (whether in contract, tort, or otherwise; and notwithstanding any fault, negligence, strict liability or product liability) with regard to any Product (including, but not limited to, any breach of or default by SEQUOIA) will in no event exceed the purchase price paid by Customer to SEQUOIA for such Product. Further, SEQUOIA will not be liable for, or be in breach of or default on account of, any delay or failure to perform as a result of any cause, condition or circumstance beyond SEQUOIA's reasonable control.

  • Page 40: Revision History

    Revision history Version 1.4 Update analog output range specification and clarify section 2.4. Version 1.3 Update maximum concentration specifications. Minor editing & clarifications. Version 1.2 Deleted GO command (no longer supported). Version 1.1 Complete revision of software, change standard outputs from ACB to Version 1.0 First released version.

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