FTS DTS-12 User manual

EXTREME ENVIRONMENTS. EXTREMELY RELIABLE.
DTS-12
SDI Turbidity Sensor
User Manual
1.800.548.4264 | www.ftsinc.com
700-DTS-12 Rev. 28 16 Apr 2020

Contact Information
Canadian Headquarters:
1065 Henry Eng Place
Victoria, BC | V9B 6B2 | Canada
www.ftsinc.com
Toll-free: 1.800.548.4264
Local: 250.478.5561
Technical support portal: http://support.ftsinc.com
Email: [e-mail]

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Table of Contents
Chapter 1 OPERATION .................................................................................................... 1
1.1 General description ......................................................................................................... 1
1.2 Unpacking ......................................................................................................................... 2
1.3 Site Selection..................................................................................................................... 2
1.3.1 Avoiding Sun Spikes 2
1.4 Installation ........................................................................................................................ 3
1.5 SDI Connection................................................................................................................. 4
1.6 SDI-12 connectorized cable ............................................................................................ 5
1.6.1 Cable Connection and Disconnection (Original model) 5
1.6.2 Cable Connection and Disconnection (V2) 8
1.7 Operation .......................................................................................................................... 9
1.7.1 Turbidity Measurement 9
1.7.2 DTS-12 Calculations 9
1.8 Address Configuration ..................................................................................................10
1.9 Calibration.......................................................................................................................10
1.10 Maintenance ...................................................................................................................10
1.10.1 Routine Cleaning 10
1.10.2 Changing the Wiper Blade 10
1.10.3 Replacing the Wiper Blade Assembly 12
1.11 Replacement Parts.........................................................................................................12
Chapter 2 QUICK START GUIDE ................................................................................... 13
2.1 Detecting the DTS-12.....................................................................................................13
2.2 Mapping the Sensor.......................................................................................................14
2.3 Configuring the DTS-12 .................................................................................................15
2.4 Setting up Logging – In-line Logging Enabled.............................................................16
2.5 Setting Up Logging - Regular Logging..........................................................................17
Chapter 3 SDI-12 COMMANDS..................................................................................... 19
3.1 Notation for SDI-12 Commands...................................................................................19
3.1.1 General SDI-12 Commands 19
3.1.2 SDI-12 Measurement and Request Data Commands 20
3.2 SDI-12 Commands for DTS-12 ver 20 or later............................................................21
3.2.1 Measurement Command Table(ver 20 and later) 22
3.2.2 Request Data Commands 22

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3.2.3 Extended (X) Commands 23
3.3 SDI COMMANDS FOR DTS-12 (ver 19 or earlier)........................................................23
3.3.1 SDI-12 Measurement Commands 24
3.3.2 Extended (C) Commands (ver 19 and earlier) 25
Appendix A TECHNICAL SPECIFICATIONS ..................................................................... 26
Appendix B ORDERING AND UPGRADE INFORMATION ............................................. 27
Document Revision History ................................................................................................ 28

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Chapter 1 OPERATION
1.1 General description
The FTS DTS-12 Turbidity Sensor (DTS-12) measures turbidity and suspended solids concentrations in
liquids. The method used is called optical back scatter and employs a detector at 90 degrees to the
incident light beam. Light is emitted into a liquid medium and any amount of reflection detected from
suspended matter is a measure of the turbidity of the medium. To achieve this result, the latest in
micro power, solid state, and infrared laser technology is used. The laser light output is modulated
and synchronously detected so that any effects from ambient light conditions are minimized. The
measurement range of the DTS-12 is 0 to 1600 NTU, making it ideal for stream and river applications.
The DTS-12 has a built-in wiper that is useful for reducing the effects of silt build up and biological
fouling of the sensor optics. The DTS-12 is factory programmed with turbidity calibration coefficients.
The micro controller applies these coefficients to the raw measurement data and computes mean,
median, maximum, minimum, variance, and BES (Best Easy Systematic estimator). All turbidity data is
returned in NTUs (Nephelometric Turbidity Units).
All control and measurement functions of the DTS-12 are initiated by sending it an SDI-121command.
Figure 1-1: DTS -12
1SDI-12 = Serial Data Interface at 1200 baud. It is a standardized protocol that defines how microprocessor based sensors can
communicate with data loggers

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1.2 Unpacking
You should have received the following materials with each DTS-12 sensor:
1. DTS-12 Turbidity Sensor complete with 25’ (or user specification) of polyurethane cable.
2. Spare wiper blade.
3. DTS-12 SDI Turbidity Sensor Operating Manual
1.3 Site Selection
The sensor should be located in an area that is representative of the water to be measured,
preferably in a shaded area.
1.3.1 Avoiding Sun Spikes
It is possible for direct or reflected sunlight to affect the DTS-12 measurements. Selecting a shaded
site will eliminate the possibility of sunlight affecting the DTS-12 turbidity readings; however, if a
shaded site is not available, if possible, mount a shade to eliminate sunlight effects on the DTS-12.
The installation directions (Section 1.4) contain further details on how to optimally deploy the DTS-12
to avoid interference from sunlight.
A typical data set from the DTS-12 from a sunlight affected deployment is shown below. Note the
daily pattern of zeroes in the turbidity measurement. In older DTS-12 units, sunlight affected
readings will be large positive spikes. The difference in how the older and newer units respond to
sunlight is due to how the DTS-12 firmware handles the erroneous readings.
Figure 1-2: DTS-12 data showing 0 NTU

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1.4 Installation
In most cases the best deployment for a turbidity sensor is inside a 4“ inner diameter protective pipe
(typically schedule 40 Aluminum or PVC pipe) that is placed in the river and fastened securely to the
shore by various means (concrete pillars, metal stakes etc.) as shown in the examples in Figure 1-3.
Figure 1-3: Example Installations
When deploying the DTS-12 sensor NEVER use the DTS-12 cable to position or remove the sensor.
Ensure its optic face is pointed away from direct sunlight. Generally, it is best to point the sensor face
downward. The exception to this is when deploying the sensor into shallow water where the bottom
or sides of the stream bed are highly reflective. For these applications, be sure to mount the sensor
so that the optic face avoids not only direct sunlight but reflected sunlight as well.
The DTS-12 must be oriented such that the optical window has at least 4 inches axial end clearance
and 2 inches radial side clearance from any physical objects (e.g. the river bottom or protective pipe).
The sensor should be located in an area that is representative of the water to be measured.
See Figure 1-4. If in doubt as to the how to deploy your DTS-12, consult FTS regarding deployment
options for your site. To aid in installation, FTS can supply a DTS-12 sensor deployment guide2.
2Part Number DTS-12-DG (Turbidity Sensor Deployment Guide Assembly)

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Figure 1-4: Typical DTS-12 Installation using FTS DTS-12 Deployment Guide
1.5 SDI Connection
The SDI cable (nominally 25 feet long) may be connected to the DTS-12 by waterproof gland or
underwater connector. Normally the free end of the cable is shipped with a length of the
polyurethane jacket removed to expose the three 20 AWG conductors. This allows maximum
flexibility when connecting to a data logger that uses a terminal strip.
The SDI cable may be optionally terminated with a 3-pin military connector for connection to a similar
connector on the Axiom Datalogger. Cable wire colour coding and FTS standard connector pinouts3
are shown in the table and diagram below:
Wire colour Pin Function
Red A +12 V DC power supply
White B Data
Black C Ground
3Waterproof military-style bayonet connector 851-06JC8-3AP50; FTS part number 520-83AP; compatible with FTS
Axiom Dataloggers.
Axial and radial
clearances
FTS DTS-12
Deployment Guide
(two sections)
Protective pipe
Push Rod attached to
deployment guide (to
prevent pulling on
the DTS-12 cable
when positioning or
removing the sensor)

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1.6 SDI-12 connectorized cable
The DTS-12 can be ordered with fixed length connectorized cables (60 and 100 ft.) that allow for quick
disconnect and re-connection. This watertight connection is submersible and permits sensor
removal from a field installation without removing the cable. In complex installations or on
installations with long cable runs this is a very desirable attribute.
There are two styles of connectorized cables and DTS-12 end caps: the original (with a black sleeve)
and the updated version (V2) with a stainless-steel sleeve which will be replacing the original cables.
Note that cables and DTS-12s are not interchangeable between the original and V2 models.
However, original DTS-12s can be returned to FTS to be fitted with the V2 end caps. Details of parts
numbers and ordering details can be found in Annex B. Note that the process for connecting the
original cable is different than the V2 (refer to sections 1.6.1 and 1.6.2).
Original V2
1.6.1 Cable Connection and Disconnection (Original model)
IMPORTANT: The FTS video “How to Connect and Disconnect the Waterproof Connectorized
Cable” should be viewed prior to attempting to disconnect or connect the cable. It can be
viewed at https://www.youtube.com/watch?v=mGD3ECbYVpw&feature=player_embedded
CAUTION: The female receptacles inside the cable connection are susceptible to
damage if the connection is bent or twisted. These actions can splay the female
connections to the point that electrical contact with the male prongs becomes
intermittent.
When working with the cable be aware that it is a tight fit and requires extremely firm handling
without twisting or bending the cable or the connector.
A thin film of dielectric grease is placed on the End Cap Flange during connection at the factory. This
facilitates the operation of the connection and should be reapplied as needed to ensure the

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connection can be unplugged. If applying dielectric grease, ensure that it is kept out of contact with
the electrical prongs and receptacles to avoid a poor electrical connection.
One of the male prongs on the DTS-12 end cap has a larger diameter than the other two. This larger
diameter prong must be aligned with the two reference nipples on the cable connector (as shown in
the connection photos) to ensure that the prongs are inserted into the correct receptacles. Forcing
insertion into the wrong position will permanently damage the connection. Aggressive twisting can
also result in bending and breaking prongs.
DO:
•Use clean dielectric grease to lubricate the
DTS-12 End Cap
•Keep prongs and receptacles free from
grease
•Keep the End Cap Prongs and Cable
Connection Receptacles dry
DO NOT:
•Disconnect the cable under water
•Leave an unconnected cable connection
underwater
•Bend or twist the cable connection during
connection or disconnection
CONNECTION
The following sequence of photos outlines the connection process.
Figure 1-5: Applying dielectric grease and aligning the prongs
NOTE: Ensure dielectric grease does not come in contact with electric prongs and receptacles.
DTS-12 End
Cap Flange
Cable
Connection
Dielectric
Grease
Dielectric Grease
on End Cap Flange
Large prong aligned
with reference nipples