Sequoia LISST-AOBS User Manual

LISST-AOBS

Super-Turbidity Sensor

User’s Manual

Version 1.3

November 2020

Sequoia Scientific, Inc.

2700 Richards Road Suite 107

Bellevue, WA, 98005, USA

Phone: [phone]; Fax: [phone]

[e-mail]; www.SequoiaSci.com

FOR TECHNICAL ASSISTANCE please contact your local 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

[e-mail] or by phone [phone].

INTRODUCTION .............................................................................................................................. 1

LISST-AOBS system parts ...................................................................................................... 1

Data interface and logging options .......................................................................................... 1

Data outputs ............................................................................................................................ 1

Wi ing ...................................................................................................................................... 2

OPERATION WITH THE NEXSENS X2 LOGGER ......................................................................... 3

About the X2 and X2-SDL ....................................................................................................... 3

WQDataLIVE ........................................................................................................................... 3

CONNECT software ................................................................................................................ 3

SDI-12 Addressing .................................................................................................................. 4

Initial setup .............................................................................................................................. 4

Parameter labels on WQDataLIVE .......................................................................................... 4

GENERAL SDI-12 OPERATION ..................................................................................................... 5

Overview .................................................................................................................................. 5

Addressing ............................................................................................................................... 5

Sampling and averaging .......................................................................................................... 5

Recommended command sequences ..................................................................................... 5

SDI-12 COMMAND REFERENCE ...................................................................................................... 6

PROCESSING LOGGED SDI-12 DATA............................................................................................... 7

Raw data ................................................................................................................................. 7

Processing ............................................................................................................................... 7

HOW SUPER-TURBIDITY MEASUREMENT WORKS .................................................................. 8

Acoustic ................................................................................................................................... 8

Optical ..................................................................................................................................... 8

Pairing ABS with turbidity ........................................................................................................ 9

Measuring Pairing Factor ........................................................................................................ 9

Pairing Results ........................................................................................................................ 9

CONNECTION DETAILS ............................................................................................................... 11

Pin functions .......................................................................................................................... 11

Male connector numbering .................................................................................................... 11

Female mating connector numbering .................................................................................... 11

Cables ................................................................................................................................... 11

SPECIFICATIONS ......................................................................................................................... 12

1

Introduction

LISST-AOBS
system parts

The LISST-AOBS is a system with three main parts:

1. LISST-ABS acoustic backscattering sensor

2. Turner Designs Turbidity Plus™ optical backscattering
sensor

3. An intelligent Y-cable/adapter that provides SDI-12
interfacing with the two sensors.

The combination of acoustic and optical sensors provides
measurements of total s concentration that are much less
affected by particle size than standard turbidity measurements (see
How Super-Turbidity Measurement Works on page 8)
For complete technical details of the Turbidity Plus™, see the

User’s Manual at https://www.turnerdesigns.com/turbidity-plus-

submersible-sensor.

Data interface
and logging
options

LI T-AOBS communicates through t S -12 protocol version

1.3. Any logger that supports SDI-12 can collect LISST-AOBS data.

Sequoia has teamed with NexSens Technology to integrate the
LISST-AOBS with the NexSens X2 logger family. The X2 can
automatically detect a LISST-AOBS and deliver its data, with data
from other connected sensors, through Wi-Fi, cellular or radio
channels. See more in Operation with the NexSens X2 logger on
page 3.

If operating with a logger other than the X2 family, see General
SDI-12 Operation on page 5.

Data outputs

LISST-ABS output is expressed in mg/liter, as calibrated with 75-90
µm microspheres. The Turbidity Plus is reported in Volts, not
calibrated in terms of concentration. The AOBS output, the
absolute concentration in mg/liter, is calculated by the user, as a
simple weighted sum of the two other parameters as described in
Processing Logged SDI-12 Data on page 7.

2

Wi ing

As with any SDI-12 device, only three connections are required:
power (nominally 12 V), ground, and SDI-12 data. However, for
compatibility with existing LISST-ABS cabling, the LISST-AOBS
uses the same 8-pin connector as a standard LISST-ABS. For
details, see Connection Details on page 11. The user must
determine how to connect the LISST-AOBS to the SDI-12 logger.
Sequoia Scientific can provide cable pigtails for this purpose.