FTS DTS-12 User manual
1.800.548.4264
www.ftshydrology.com
700-DTS-12 Rev. 20, 08 Jan 2014
DTS-12
SDI Turbidity Sensor
User Manual
Contact information
FTS
1065 Henry Eng Place
Victoria, B.C., V9B 6B2
CANADA
www.ftshydrology.com
Toll-free
1-800-548-4264
Local
250-478-5561
Technical support
support.ftshydrology.com
Revision History
Date
Person
Description
27 Jan 2012
RG
Update for DTS-12A and format to current standard
10 Dec 2012
PB
Correction made to BES equation on pg 12
16 May 2013
CV
Clarification improvements and added appendices
13 June 2013
CV
Updated cable connect/disconnect instructions and deployment guide
12 July 2013
CV
Updated deployment guide drawings
08 Jan 2013
CV
Corrected typo in DTS request data response
Table of contents
Contact information ........................................................................................................................................... ii
Chapter 1 Operation ................................................................................................................................... 5
1.1 General description ...........................................................................................................................................................6
1.2 Unpacking .............................................................................................................................................................................7
1.3 Installation.............................................................................................................................................................................7
1.4 SDI Connection....................................................................................................................................................................9
1.5 Operation............................................................................................................................................................................11
1.6 Address configuration ...................................................................................................................................................12
1.7 Calibration and maintenance .....................................................................................................................................12
1.8 Replacement Parts ..........................................................................................................................................................14
Chapter 2 SDI Commands ........................................................................................................................ 15
2.1 Notation for SDI commands........................................................................................................................................16
2.2 Commands recognized by the DTS-12 ...................................................................................................................16
2.3 General SDI commands.................................................................................................................................................18
2.4 SDI measurement and data commands .................................................................................................................18
2.5 Extended command set ................................................................................................................................................21
Chapter 3 Technical specifications ........................................................................................................ 22
Appendix A
Commands recognized by the DTS-12 (historical) ..........................................................................................................25
Chapter 1 Operation
Chapter contents
1.1 General description ...........................................................................................................................................................6
1.2 Unpacking.............................................................................................................................................................................7
1.3 Installation ............................................................................................................................................................................7
1.4 SDI Connection ...................................................................................................................................................................9
1.4.1 SDI-12 connectorized cable
1.4.1.1 Cable connection
1.4.1.2 Cable disconnection
1.5 Operation ........................................................................................................................................................................... 11
1.5.1 Startup Operation of Turbidity Sensor
1.5.2 Turbidity measurement
1.5.3 DTS-12 calculations
1.6 Address configuration................................................................................................................................................... 12
1.7 Calibration and maintenance..................................................................................................................................... 12
1.8 Replacement Parts .......................................................................................................................................................... 14
DTS-12 User Manual Chapter 1 Operation
page 6
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. In
practice what this means is that 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
1500 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 a SDI-12 command. SDI-12 stands
for Serial Data Interface at 1200 baud. It is a standardized protocol that defines how microprocessor based sensors
can communicate with data loggers.
Figure 1-1: DTS-12 Turbidity Sensor
DTS-12 User Manual Chapter 1 Operation
page 7
1.2 Unpacking
You should have received the following materials with each DTS-12 sensor:
1. DTS-12 Turbidity
2. Spare wiper blade.
3. DTS-12 SDI Turbidity Sensor Operating Manual.
1.3 Installation
In most cases the best deployment for a turbidity sensor is inside protective tubing (typically PVC pipe) that is
placed in the river and fastened securely to the shore by various means (concrete pillars, metal stakes etc.).
Figure 1-2 shows such an installation. If in doubt consult FTS regarding the best deployment options for your site.
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). The sensor should be located in an area that
is representative of the water to be measured.
Figure 1-2: Typical DTS-12 installation
DTS-12 User Manual Chapter 1 Operation
page 8
To aid in installation, FTS can supply a DTS-12 sensor deployment guidedeployment guide
conjunction with the user supplied and constructed 4-inch ID deployment tube. The deployment guide can be slid
down the inside of the protective tubing (typically schedule 40 Aluminum or PVC pipe) that is placed in the river.
Examples are shown in the figures below.
Figure 1-3: DTS-12 deployment guide (diagram)
Figure 1-4: ABS Deployment Guide installed on a DTS-12
DTS-12 User Manual Chapter 1 Operation
page 9
Figure 1-5: Typical DTS-12 deployment tube and deployment guide combination
1.4 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 similar connector on
the data logger. Cable wire colour coding and FTS standard connector
1
pinouts are shown in the table and
diagram below:
Wire colour
Pin1
Function
Red
A
+12 V DC power supply
White
B
Data
Black
C
Ground
1
Waterproof military-style bayonet connector 851-06JC8-3AP50; FTS part number 520-83AP; compatible with FTS
Axiom dataloggers.
DTS-12 User Manual Chapter 1 Operation
page 10
1.4.1 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 easy 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.
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 connection can be unplugged.
If doing so, ensure that the grease is kept out of contact with the electrical prongs and receptacles to avoid a poor
electrical connection.
Warning: Because of the tight fit of this connection, inexperienced users tend to twist and bend the connection
when connecting or disconnecting the cable. This inappropriate handling WILL damage the female
receptacles inside the Cable Connection.
See “How to connect and disconnect the DTS-12 turbidity sensor waterproof connectorized cable” video on the FTS
web page for proper procedure. http://www.ftsenvironmental.com/video/
1.4.1.1 Cable connection
Figure 1-6: Cable connection details
DTS-12 User Manual Chapter 1 Operation
page 11
1.4.1.2 Cable disconnection
After unscrewing the locking collar slide it up the cable out of your way. Firmly grip the probe and cable
connection as outlined below and rotate and pull the connection apart. Ensure you do not bend or twist the cable
connection.
Figure 1-7: Cable disconnection details
Caution:
The female receptacles inside the cable connection are susceptible to damage if the connection is bent or twisted.
These actions can splay out the female connections to the point that electrical contact with the male prongs
becomes intermittent. In addition, 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 above) 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.
1. Do use clean dielectric grease to lubricate the DTS-12 End Cap
2. Do keep prongs and receptacles free from grease
3. Do keep the End Cap Prongs and Cable Connection Receptacles dry
4. Do not disconnect the cable under water
5. Do not leave an unconnected cable connection underwater
6. Do not bend or twist the cable connection during connection or disconnection
1.5 Operation
1.5.1 Startup Operation of Turbidity Sensor
When power is first applied to the DTS-12 a wipe cycle will occur. This is a normal part of the sensor initialization.
When the wiper returns to its normal parked position the DTS-12 is ready to accept SDI commands.
1.5.2 Turbidity measurement
A measurement is initiated when the logger sends an appropriate SDI command to the DTS-12. When this
happens, the DTS-12 will execute a measurement cycle consisting of the following steps:
DTS-12 User Manual Chapter 1 Operation
page 12
1. Power up the sensor head.
2. Calibrate the analog to digital converter circuitry.
3. Read the water temperature
4. Do a wipe (if the command calls for a wipe) if the water temperature is not too low
5. Acquire 100 samples at 20 samples per second.
6. Perform statistical calculations as required.
After about 10 or 20 seconds (this time is dependent on the type of measurement requested) the sensor will
respond with a service reque
wiper may be activated explicitly as a single operation or implicitly as the first part of a measurement command.
See the section on SDI commands for the individual command descriptions.
Note: A wipe operation will add an additional 5 seconds to the measurement operation.
1.5.3 DTS-12 calculations
The statistical calculations performed by the DTS-12 on the 100 samples are shown below:
Where
1.6 Address configuration
The DTS-12 is shipped with default address 0 (unless shipped as part of an integrated FTS system). Refer to section
2.3.3 Change Address
1.7 Calibration and maintenance
The only field maintenance required by the DTS-12 is a periodic check of the wiper for deterioration or fouling
with biological or other material. If fouling is detected and the wiper blade is in otherwise good condition it may
be cleaned and re-used. Use a soft lint free cloth or wipe with Methyl or Ethyl alcohol, soaps or detergents to clean
the, wiper, optic surface and body of the probe. You may also use a soft toothbrush to help remove the material.
Care must be taken not to scratch the window as this may affect the sensor calibration. Do not use harsh or
DTS-12 User Manual Chapter 1 Operation
page 13
abrasive cleansers or petroleum products. If the wiper blade edge appears ragged or uneven then the wiper
assembly should be replaced. Each DTS-12 is shipped with a spare piece of wiper material (698-DTS12-WIPER)
packaged in a small zip-lock bag attached to the cable. These can be changed as shown below. Complete
replacement wiper arm assemblies may also be purchased from FTS (part # DTS12-WIPER). The complete assembly
can be changed by loosening the thumbscrew to remove the old wiper assembly and replacing it with the new
wiper assembly.
If tools and a work area are available then replacing the wiper blade is an option. To replace the wiper blade refer
to Figure 1-8 and perform the following operations:
1. Remove the wiper assembly consisting of the wiper arm and wiper blade by undoing the wiper arm
thumbscrew with your fingers. To reduce unnecessary stress on the wiper drive system hold the wiper
arm while turning the thumbscrew counter clockwise
2. On older models remove the split pin from the wiper arm by tapping it out with a punch of the same
diameter. The current design incorporates a slot with a circular opening at one end that allows the wiper
material to be maneuvered out of, or into the slot.
3. In both cases slide the old blade off the wiper arm.
4. Reassemble using a fresh wiper blade following the previous steps in reverse order.
Wiper Blade
Wiper Armature
M3 X 8 Thumbscrew
Figure 1-8: DTS-12 Wiper Arm Detail
DTS-12 User Manual Chapter 1 Operation
page 14
1.8 Replacement Parts
If replacement parts are required, the entire wiper assembly shown in Figure 1-8 (p. 13) can be ordered from FTS
by specifying part number DTS12-WIPER. If individual components are required, specify part number according to
the table below.
FTS Part Number
Description
DTS12-WIPER
Wiper and Armature assembly
993-WIPER-ARM
Wiper Armature
698-DTS12-WIPER
Wiper Blade
610-M3X8-TMB
M3 x 8 Thumbscrew
Chapter 2 SDI Commands
Chapter contents
2.1 Notation for SDI commands........................................................................................................................................ 16
2.2 Commands recognized by the DTS-12................................................................................................................... 16
2.3 General SDI commands ................................................................................................................................................ 18
2.3.1 Address Query
2.3.2 Acknowledge Active
2.3.3 Change Address
2.3.4 Send Identification
2.4 SDI measurement and data commands................................................................................................................. 18
2.4.1 Start Measurement
2.4.2 Start Concurrent Measurement
2.4.3 Request Data
2.4.4 Continuous Measurement
2.4.5 Start Verification
2.5 Extended command set................................................................................................................................................ 21
2.5.1 Enable Median in M command
2.5.2 Enable Mean (average) in M command
2.5.3 Report M command status
2.5.4 Set low temperature wipe cutoff value
2.5.5 Enable low temperature wipe cutoff
2.5.6 Disable low temperature wipe cutoff
2.5.7 Report low temperature wipe cutoff status
DTS-12 User Manual Chapter 2 SDI Commands
page 16
2.1 Notation for SDI commands
In the end, SDI commands are strings of characters sent to the SDI device. The format of those strings is important,
of course, and to specify the format of SDI commands we use different typefaces. All commands (and the replies
from the device) are represented in a monospaced font. Different parts of a command are represented with variants
on this text format.
Item
Explanation
Text representation
Command literal
Part of a command that must be
reproduced literally as it appears
X
Command
parameter
Part of a command that must be filled in
with an appropriate value
data
Address part of
command
First character of command (except
Address Query). Valid values 0-9, a-z, A-Z.
a
2.2 Commands recognized by the DTS-12
The table below provides a quick reference to the commands recognized by the DTS-12. For details on these
commands, see the following sections.
IMPORTANT ! The commands below are for DTS-12 version 20 and up. To determine your version number
perform an Identification Command and look at the VX field. Identification response = aCN#FTS----DTS12VX-
SN#. See Appendix A for older command sets.
Command name
Command code
Notes
Address Query
?!
Acknowledge Active
a!
Change Address
aAb!
bis the new address, a single alphanumeric
character in the range 0-9, a-z, A-Z
Send Identification
aI!
Resp = aCN#FTS----DTS12VX-SN#
a = address
CN# = SDI-12 compatibility number
FTS = manufacturer identifier
DTS12 = sensor type
VX = firmware version number
SN# = serial number
Start Measurement (general)
aM!, aMC!,
aMn!, aMCn!
Cfollowing a command requests a CRC code in
the data return (Dcommand)
nis a digit between 1 and 9
Start Concurrent Measurement
(general)
aC!, aCC!,
aCn!, aCCn!
Cfollowing a command requests a CRC code in
the data return (Dcommand)
nis a digit between 1 and 9
Start Measurement:
Median Mode (factory default)=
Temperature, Median Turbidity,
Variance of the Mean, Wipe Status*
aM! , aMC!,
aM0!,aM0C!
aC!, aCC!
Causes a wipe before the measurement
Median mode returns 4 data points.
DTS-12 User Manual Chapter 2 SDI Commands
page 17
Command name
Command code
Notes
Start Measurement:
Mean (average) Mode =
Temperature, Mean Turbidity,
Variance of the Mean
aM! , aMC!,
aM0!,aM0C!
aC!, aCC!
No wipe before measurement
Mean (average) mode returns 3 data points.
Start Measurement: Mean, Variance,
Median, BES, Min, Max, Temperature
aM1!, aMC1!,
aC1!, aCC1!
No wipe
Start Measurement: Mean, Variance,
Median, BES, Min, Max,
Temperature, wipe status*
aM2!, aMC2!,
aC2!, aCC2!
Wipe before measurement
Start Measurement: Single turbidity
measurement
aM3!, aMC3!,
aC3!, aCC3!
No wipe
Reserved for factory use
aM4! , aMC4!,
aC4!, aCC4!
Not used
aM5!, aMC5!,
aC5!, aCC5!
Not used
aM6!, aMC6!,
aC6!, aCC6!
Not used
aM7!, aMC7!,
aC7!, aCC7!
Wipe sensor window: wipe status*
aM8!, aMC8!,
aC8!, aCC8!
Data return is wipe status
Reserved for factory use
aM9!, aMC9!,
aC9!, aCC9!
Request Data
aDn!
nis a digit between 0 and 9
aD0! commands return all available
data from the most recent measurement
command
Continuous Measurements (Read)
aR!, aRC!
Cfollowing a command requests a CRC code in
the data return
Start Verification: no data returned
aV!
Verifies SDI communication
Enable Median M command
aX se mc m!
Reports median turbidity
Enable Mean(average) M command
aX se mc a!
Reports average (mean) turbidity
Report M command status
aX g mc!
Set low temperature wipe cutoff
value
aX se ct xxx!
Temperature xxx (any decimal number), C
Enable low temperature wipe cutoff
aX se ce y!
Disable low temperature wipe
cutoff
aX se ce n!
Default setting (disabled)
Report low temperature wipe cutoff
status
aX g ce!
Temperature, C
* Wipe Code
0 = Wiped
1 = Too cold (below set temperature value so wipe suppressed)
2=No wipe for any other reason other than temperature suppressed
3=Attempted wipe
DTS-12 User Manual Chapter 2 SDI Commands
page 18
2.3 General SDI commands
General SDI commands are used for housekeeping issues such as device address configuration, device
identification and confirmation of device communications. General SDI-12 version 1.3 commands are as follows.
2.3.1 Address Query
This command requests the address of the SDI sensor.
String
Note
Cmd
?!
request the (single) device on this bus to report its address
Resp
0
the device is configured for address 0
only one SDI device should be connected to the bus when
using this command; problems arise when several devices
respond on the same bus
2.3.2 Acknowledge Active
This command queries whether a sensor is present on the SDI bus at the specified address.
String
Note
Cmd
0!
request the device at address 0 to confirm it is active
Resp
0
a device is present at address 0
2.3.3 Change Address
String
Note
Cmd
0A3!
change the address of the device at SDI address 0 to 3
Resp
3
response confirms change
2.3.4 Send Identification
This command requests detailed identification information from the addressed sensor.
String
Note
Cmd
3I!
Resp
313FTS-----DTS12--v1SN#-34567
3device SDI address
13 compatible with SDI-12 version 1.3
FTS-----
DTS12- sensor model
-v1 version 1 of sensor firmware
SN#-34567 sensor serial number
2.4 SDI measurement and data commands
SDI data commands request data from the sensor.
DTS-12 User Manual Chapter 2 SDI Commands
page 19
2.4.1 Start Measurement
This command is used trigger a measurement on the addressed sensor. The sensor will not return data, instead the
sensor will return the duration of the measurement as well as the number of data points returned by the
measurement. The data is read using a subsequent Request Data command. Refer to Tables 2 and 3 for the
specifics of the data returned from the sensor.
String
Note
Cmd
3M! or 3MC!
start a measurement on sensor at address 3 (without or with
CRC in data response, respectively)
Resp
30124
3device SDI address
012 measurement delay (until data is ready; seconds)
4number of data points returned
2.4.2 Start Concurrent Measurement
The concurrent measurement command allows a sensor to take a measurement while other SDI sensors are also
taking measurements. The Start Concurrent Measurement Command operates in the same manner and returns
the same information as the Start Measurement command (refer to Table 2).
String
Note
Cmd
3C! or 3CC!
start a concurrent measurement on sensor at address 3
(without or with CRC in data response, respectively)
Resp
300704
3device SDI address
007 measurement delay (until data is ready; seconds)
04 number of data points returned
2.4.3 Request Data
This command requests the data generated by the preceding Measurement (Mor C) command. An aD0! command
is always the first command sent to retrieve the data. If additional data needs to be read, then an aD1! command is
sent, then and aD2! etc., up to aD9! as required to retrieve all data.
String
Note
Cmd
3M2!
start a measurement on sensor at address 3
Resp
30288
3device SDI address
028 measurement delay (until data is ready;
seconds)
8number of data points returned
Cmd
3D0!
request data from previous measurement command
Resp
3+2.18+0.0007+2.17+2.17+2.15+2.26
3sensor SDI address
+2.18 mean turbidity
+0.0007 variance
+0.217 median
+2.17 BES
+2.15 min
2.26 max
Cmd
3D1!
request more data from previous measurement
command
DTS-12 User Manual Chapter 2 SDI Commands
page 20
Resp
3+23.4
3sensor SDI address
+23.4 temperature
Cmd
0MC!
start a measurement on sensor at address 0, with CRC
in data response
Resp
00074
0device SDI address
007 measurement delay (until data is ready;
seconds)
4number of data points returned
Cmd
0D0!
request data from previous measurement command
Resp
3+23.5+0.0+0.244694+0@Pu
3sensor SDI address
+23.5 temperature in degrees Celsius
+0.0 mean turbidity
+0.244694 variance
0 wipe code (median mode)
@Pu CRC code
2.4.4 Continuous Measurement
This command is not supported by the sensor. The response of the sensor to a Continuous Measurement
command is shown below.
String
Note
Cmd
1R!
perform a continuous measurement read on sensor at
address 3
Resp
1
1sensor SDI address
DTS-12 is not a continuous measurement device. No data is
returned.
Cmd
1RC!
perform a continuous measurement read on sensor at
address 3, with CRC code in data response
Resp
1MSA
1sensor SDI address
MSA CRC code
DTS-12 is not a continuous measurement device. No data is
returned.
2.4.5 Start Verification
This command is not supported by the sensor. The response of the sensor to a Start Verification command is
shown below.
String
Note
Cmd
3V!
start verification on sensor at address 3
Resp
30000
3device SDI address
000 measurement delay (until data is ready; seconds)
0no data is returned
Other manuals for DTS-12
1
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