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English
Quick Reference
Side Looking Doppler
OTT SLD
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We reserve the right to make technical changes and improvements without notice.
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Table of contents
1 System description 5
2 Parts supplied/components of the OTT SLD 6
3 Preparing for installation 7
3.1 Installing the operating software 7
3.2 Cable connection 7
3.3 Checking the communication 8
3.4 Programming the datalogger 8
4 Installation 9
4.1 Calibrating the pressure sensor 9
4.2 Setting the operating parameters 10
4.3 Aligning the sensor 15
4.4 Checking the water level 17
4.5 Checking the range 17
5 Operation 19
5.1 Disconnecting the PC from the sensor 19
5.2 Connection to datalogger 20
5.3 Verifying the data 21
Appendix A 22
A.1 Technical data 22
A.2 Information on electromagnetic compatibility 23
A.3 Firmware update 23
Appendix B – SDI-12 commands and responses 24
B.1 Basic commands 24
B.2 Advanced commands 30
Appendix C – OTT SLD and Modbus fieldbus protocol 31
Appendix D – Representation of the accumulated discharge volumes 34
D.1 Representation in SDI-12 protocol 34
D.2 Representation in Modbus protocol 35
Appendix E – Installation examples 36
E.1 Example #1 – Installation at a staircase for water level measurement
(mounting rail with slide) 37
E.2 Example #2 – Installation at a staircase for water level measurement
(dual T rail with roller slide) 38
E.3 Example #3 – Installation at a natural river bank slope
(mounting rail with slide) 39
E.4 Example #4 – Installation at a vertical edge wall
(mounting rail with slide) 40
E.5 Example #5 – Installation on a concrete base in the river bed 41
E.6 Example #6 – Installation at a sheet pile 42
E.7 Example #7 – Installation at a vertical edge wall (mounting plate) 43
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1 System description
During installation, the sensor is connected to the PC and parameterized using a
serial interface (a). After completing the installation, serial communication is terminated. Thereafter, the sensor is controlled from the datalogger through SDI-12 or
RS-422/RS-485 (b) (SDI-12 protocol).
a) Sensor – Cable – PC/power supply
b) Sensor – Cable – Datalogger/power supply
Fig. 1: Schematic diagram of the
wiring configuration used for setting
the operating parameters.
Fig. 2: Schematic diagram of the wiring
configuration used for measuring.
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2 Parts supplied/components of the OTT SLD
Please check the contents of the shipping crate against the packing list supplied.
The sensor specification may be obtained from the name plate.
Basically, the OTT SLD scope of supply includes 3 items:
Connection cable
Sensor
Operating software CD
The following instrument versions are available:
Discharge
– Measured variables: Flow velocity and water level;
– Built-in discharge calculation;
– Frequencies: 600 kHz, 1.0 MHz, or 2.0 MHz;
– Design: Horizontal or vertical type;
– Interfaces: RS-232 and SDI-12 or RS-422/RS-485 (SDI-12 protocol).
Velocity (flow velocity)
– Measured variable: Flow velocity;
– Frequencies: 600 kHz, 1.0 MHz, or 2.0 MHz;
– Design: Horizontal or vertical type;
– Interface: RS-232 and SDI-12 or RS-422/RS-485 (SDI-12 protocol).
Fig. 3: Components of the OTT SLD.
1 – Sensor head
2 – Sensor housing
3 – End piece with connector socket
The figure shows the "Discharge" instrument
version (measured variable: flow velocity
and discharge); Frequency: 1.0 MHz;
horizontal installation; RS-422/RS-485
interface (SDI-12 protocol).
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3 Preparing for installation
This chapter covers preparing the installation and may be carried out in office.
Within the operating software menus, please use dots instead of commas as
decimal separators (e.g. 1.5m for one and a half meters).
3.1 Installing the operating software
The software is run on the Microsoft Windows XP
®
operating system or later.
Insert the CD-ROM into the CD drive. Start the "setup.exe" file. Follow the instructions displayed.
3.2 Cable connection
There are 2 cable options.
a) RS-232 in combination with SDI-12 (maximum 65m);
b) RS-422/RS-485 (SDI-12 protocol) (maximum 500m).
The cables have a coded underwater connector.
Spray the contact pins of the connector and the socket with a silicone spray.
Use the "Scotch™ 1609" silicone spray manufactured by "3M" for this
purpose. Each time you subsequently establish an electrical connection, you
must spray again!
Attach the connector to the plug on the sensor. Secure the connection by
tightening the cap nut (manually – don't use a tool).
The second cable end is open. For communication with your PC, you can
temporarily attach the sub-D socket (9-pin) provided for this open end.
Connect this to your PC's serial interface (possibly RS-232/use a USB adapter).
Connect "+ Supply" to the positive pole and "GND Supply" to the negative
pole of your 12V power supply.
1
2
5
6
7
8
3
4
0
RS-232
Supply
+ Supply (typ. +12 V)
GND
SDI-12
RS-232
Not used
OTT SLD
Shielding
RS-232 Rx
RS-232 Tx
SDI-12 Data
SDI-12 GND
1
2
5
6
7
8
3
4
0
OTT SLD
RS-422
Supply
+ Supply (typ. +12 V)
GND
Not used
RS-422
RS-422
Shielding
RS-422 Tx–
RS-422 Tx+
RS-422 Rx+
RS-422 Rx–
Fig. 5: RS-422 connection diagram.
Fig. 4: RS-232 connection diagram.
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Please note:
Never grease the contact pins. Risk of corrosion!
Never pull on the cable when disconnecting the connector from the plug!
Handle the connector with care! Avoid unnecessary long-term exposure to
sunlight!
Avoid placing tensile load on the cable!
Do not bend the cable!
Recommendation: Check the connection on a regular basis.
3.3 Checking the communication
Start the OTT SLD EasyUse Software.
From the "Communication" menu, select the "Serial Port" option.
Select "OK" to confirm the "9600" option of the "Baud rate" item.
From "Communication", select the "Connect" option. Now your PC is con -
nected to the sensor.
3.4 Programming the datalogger
Configure your datalogger (refer to the
OTT netDL/OTT DuoSens Operating
Instructions). In Appendix B, all SDI-12 commands of the OTT SLD are described.
Make sure that the SDI-12 address of the datalogger matches the SDI-12 address
of the OTT SLD.
Please note: For an OTT SLD "Discharge" instrument version in combination
with an OTT DuoSens, discharge calculation must be performed in the OTT SLD!
There is no option for creating a configuration for calculating the discharge within
the OTT DuoSens.
Fig. 6: Selecting the serial port.
Fig. 7: Setting the baud rate.
Fig. 8: Connection test is successful.
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4 Installation
Please note: Install the OTT SLD in such a way that it will be immersed in water
under any operating conditions. In case this cannot be ensured, provide suitable
equipment for automatically disconnecting the operating voltage when the unit is
"falling dry". Only thus, safe and trouble-free operation of the OTT SLD will be
ensured.
Route the cable from the place of installation of the sensor to the location of the
datalogger. Now repeat all steps described in Chapter 3.
4.1 Calibrating the pressure sensor
The pressure sensor is available only in combination with water level measurement
("Discharge" instrument version).
Calibrate the pressure sensor at the place of installation. The sensor may be
calibrated when it is inside or outside the water.
Perform the following steps:
From the "On-line" menu, select the "Set Pressure Offset" option.
Set the present water coverage of the sensor (outside the water: 0m).
Select "OK" to confirm. The pressure sensor will be calibrated now.
Fig. 9: Set pressure offset.
Fig. 10: Setting the offset.
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4.2 Setting the operating parameters
When you want to create a completely new parameterization,
– select the "Deployment planning"option from the "Deployment" menu;
– select "Load From Instrument", when you want to use the configuration stored
in the sensor.
Select the "Standard" tab and parameterize the following boxes:
Sensor :
Frequency Select the acoustic frequency of the sensor.
Enter the measurement interval. The measurement interval is
triggered by the sensor during serial communication only.
When a datalogger is connected (SDI-12 protocol), this interval is controlled by it. In such a case, leave the measurement
interval of 300 seconds unchanged! Minimum measurement
interval [s] = Flow average interval [s] + Level average
interval [s] + 5 s
River bank Select the river bank side (in flow direction) at which the OTT
SLD is installed: "Left" or "Right". The OTT SLD is designed to
be installed at the right-hand bank side of a flowing waterway. When it is installed on the left-hand bank side, it will
provide negative flow velocities because of its design. When
"Left" is selected, the OTT SLD will change the sign of the
negative flow velocities the absolute amount of which is,
however, correct.
Fig. 11: "Deployment" menu.
Measurement
interval
Fig. 12: "Deployment Planning"
option, "Standard" tab.
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Flow:
Average interval Enter the averaging interval for velocity measurement.
The recommended values are 60s (30s (high flow
velocities above 1m/s) …120s (low flow velocities up
to approx. 0.3m/s).
Cell size Enter the cell size (refer to Fig. 13).
Blanking distance Enter the blanking distance (refer to Fig. 13).
Ship/Vessel filter:
The ship filter is able to detect ships passing the measuring station. To this end, the
OTT SLD uses a mathematical algorithm to compare the signal amplitudes of the
echoed signals in measuring cells that may be selected. When no ship is passing the
measuring station, the signal amplitudes are continuously decreasing with increasing
distance to the OTT SLD. When a measuring cell has a signal amplitude caused by
reflection at an object that is significantly higher than that of the previous signal, this
is considered to be an indication of a ship passing by. In such a case, the OTT SLD
will retain the previous measured value for an adjustable period of time.
Please note: The ship filter is available only for the „Discharge“ instrument version
and with the „Discharge“ checkbox selected (see Fig. 15)! In any other case the
boxes for setting parameters are dimmed.
Tolerance Responsiveness of the ship filter.
Recommendation for setting the value: During commissioning, set the slider to the center position between "Low" and
"High". Thereafter, use the on-line measurement window
to check whether the ship filter is responding appropriately. As necessary, move the slider in the "Low" direction
(ship filter has detected a ship passing by although there
is only flotsam), or move the slider in the "High" direction
(ship filter has not detected that a ship is passing by).
Hold old value for [s] Time in seconds the OTT SLD will retain the previous
value after the ship filter has detected a ship passing by.
Message shown in the online measurement window:
"Ship filter holding".
Start Cell First measuring cell in which the ship filter is active;
End Cell Last measuring cell in which the ship filter is active.
From the defined measured volume, select the range in
which ships may actually pass by.
Fig. 13: Schematic diagram for
"Cell size" and "Blanking".
Fig. 14: Available status messages of the
ship filter (On-line measurement window).
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Cell 1 Cell 2 Cell 3 Cell 4 Cell 5 Cell 6 Cell 7 Cell 8 Cell 9
OTT SLD
Blanking
Cell size
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Level:
Average interval Enter the averaging interval for the water level measure-
ment. The recommended value is 15s (up to 30s).
Quality threshold Enter a value for the quality lower limit of the water level
measurement. The optimum setting is between 80 and 120.
Alternatively, you can also enter "0". In this case the
OTT SLD determines the value for the lower quality limit
for each measurement independently (recommended procedure). Detailed information can be found in chapter4.4.
Caution: For sensors without water level measurement (instrument version:
"Velocity"; refer to Chapter 2), the "Level" checkbox must not be selected.
Speed of sound parameter:
The speed of sound in water depends on its density. The density itself is influenced
by the temperature and the salinity of the water. The OTT SLD calculates the flow
velocity of a water body based on the speed of sound. There are two ways to do
this:
Measured salinity The OTT SLD compensates the speed of sound (reference
velocity: 1500 m/s at 20 °C and 0 ppt) on the basis of
the currently measured water temperature and the entered
salt content. You have to measure the salt content once
on site and enter it in the unit ppt (parts per thousand;
1 ppt ≈ 1 g/l). If the salt content is not known, enter "0".
The OTT SLD then calculates on the basis of pure water.
(The influence of the salt content on the speed of sound is
clearly smaller than the influence of the temperature).
Fixed There is no compensation of the speed of sound based on
the water temperature and the salt content. The OTT SLD
calculates the flow velocity based on the set speed of
sound. With this setting, strong fluctuations of the water
temperature and the salt content inevitably lead to a higher
inaccuracy of the flow velocity.
Deployment planning:
Power consumption Reflects the energy consumption in Wh per day.
Power level – Flow This parameter is set by the OTT SLD.
Default: "HIGH".
Power level – Level This parameter is set by the OTT SLD.
Default: "LOW".
For "Discharge" instrument version: Select the "Discharge" tab.
Select the "Discharge" checkbox and parameterize the following boxes:
Discharge:
Total volume interval Interval in hours that the OTT SLD uses to determine
the accumulated discharge from individual Q values.
Value range: 1 … 24 hours.
Start Cell The first measuring cell the OTT SLD uses for discharge
calculation. (Example based on the result of the range
check of Fig. 23: Cell #1).
End Cell The last measuring cell the OTT SLD uses for discharge
calculation. (Example based on the result of the range
check of Fig. 23: Cell #4).
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k*A Table:
Data pairs for "Water level" and corrected areas
"k*A". You may manually enter individual data pairs
or load them into the operating software as a complete
table (refer to the "Import Prodis 2 k*A table" button).
Loads a complete table into the operating software that
was created using the OTT Prodis 2 calibrating software. File format: "*.XML".
Please note:
The k*A table created must match the cells used! When the OTT SLD e.g. uses
the cell numbers 3 through 7 for discharge calculation, the k*A table must also
have been created based on these cells.
To set the reference height of the OTT SLD water level sensor later (see
Figure 17), you must first prepare the k*A table generated by OTT Prodis 2:
Open the table (file format: "*.XML") with any text editor; e.g. with the
"Notepad" from Microsoft (included with the operating system).
Delete the line "<zeropointlevel>...</zeropointlevel>" completely; see
Figure 16. Do not make any further changes to the file.
Save the file. You can then import the table using the "Import Prodis 2 k*A
table" function.
Fig. 15: "Deployment Planning"
option, "Discharge" tab.
Water level [m]
k*A [m2]
Import Prodis 2
k*A table
Fig. 16: Prepare OTT Prodis 2
k*A table.
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Using the settings made in this window, the OTT SLD calculates the discharge "Q"
from the flow velocity measured as well as from the table values for water level
and corrected areas (k*A) ("Q" calculation based on the index method). Moreover, the OTT SLD uses the Q values calculated to determine an accumulated
discharge value over a selectable period of time. Between two measurement
intervals, the discharge is assumed to be constant.
Example
– Measurement interval: 5 minutes (300 seconds)
– Accumulating interval: 1 hour
Q
Accum.
= Q1 x 300 + Q2 x 300 + … + Q11 x 300 + Q12 x 300
Within one accumulating interval, the accumulated discharge Q
Accum
will increase
with every measurement interval. At the beginning of a new accumulating interval,
the OTT SLD will reset this value to zero.
Set the reference height of the OTT SLD water level sensor:
– When the k*A table used is based on the "coverage" of the water level
sensor (OTT SLD ↔ water surface distance) ➝ Enter "0".
– When the k*A table used is based on another reference point (e.g. "above
mean sea level") ➝ Enter the distance from the reference point to the water
level sensor.
Select the "OK" button.
Do not start the online data collection: Select the "No" button.
When you want to change the parameterization at a later time, data collection
must be stopped! Then proceed as described in this section.
Fig. 17: Entering the reference height for
the OTT SLD water level sensor.
Fig. 18: Starting the on-line data collection.
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4.3 Aligning the sensor
Attach the sensor to the bracket. Position the sensor in the water as desired. To
check proper operation of the sensor, the sensor head must be within the water.
The pressure cell requires a minimum water coverage of 15cm. Ensure that there
are no obstructions in the water that may affect sensor operation. Perform the
alignment test as follows:
From the "On-line" menu, select the "Start Level Check" option.
In the lower left corner of the window, "Tilt", „"Pitch", and "Roll" are displayed.
Move the sensor so that "OK" will be shown for "Tilt". Fix the sensor in this position.
Fig. 19: Starting the level check.
Fig. 20: "Level check" evaluation window.
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0°
0°
z
x
Roll
Roll = Roll angle in x axis
Pitch = Tilt angle in y axis
y
Pitch
positive pitch/roll values* (OTT SLD rotated clockwise)
OTT SLD horizontal instrument versionOTT SLD vertical instrument version
negative pitch/roll values* (OTT SLD rotated counter-clockwise)
z
x
Roll
y
Pitch
When installing the OTT SLD, align it such that the “Tilt”** value is within the range of -3° … +3° (“Tilt: OK”)
(Tilt = Pitch2 + Roll2)
*
Value range: ±25° (shown in gray, beyond this value, the OTT SLD will set bit 3/ bit 4 in status value to “1”
**
Refer to “Level Check” window (“On-line” menu) in OTT EasyUse software
+
+
+
+
Fig. 21: Pitch/Roll values when aligning the OTT SLD.
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4.4 Checking the water level
The water level is determined by evaluating the runtime an acoustic signal takes
from the sensor to the water surface and back. Runtime measurement is supported
by a pressure sensor.
Figure 20 shows the strength of the amplitude (green) and the quality (yellow) of
the received (reflected) signal in the horizontal axis. The vertical axis shows the
distance of the water surface to the sensor. The dashed horizontal white line
shows the water surface height determined by the pressure sensor, and the purple
line shows the water surface height measured by the acoustic sensor. The sensor
takes into account only those values that are within ±30cm of the pressure sensor
value (red dashed lines).
Furthermore, the screen shows information on the alignment of the sensor at the
bottom left-hand side (refer to Chapter 4.3), the water temperature in °C (degC)
and water depth (Level) in the bottom center, and the value of the pressure sensor
(Pressure) as well as the combined water level (Level (P)) at the bottom right-hand
side. The combined water level includes the pressure and acoustic sensors to avoid
incorrect measurements caused by e.g. reflections. For further calculations, the
combined water level is recommended to be used.
Figure 20 shows 3 significant amplitudes at approx. 65cm, 130cm, and
195cm. This is an indication of multiple reflections. In the "Deployment" dialog,
set the threshold (Threshold – the red vertical line in the Figure) so that the quality
and amplitude values corresponding to the present water height will exceed the
threshold. Any values below the threshold will not be included in the calculation.
Complete the test: From the "On-line" menu, select the "Stop Data Collection"
option.
4.5 Checking the range
The range check is to ensure that the flow velocity is gathered in an optimum way.
It helps identify underwater obstructions and adapt the size of the measuring cell
and the blanking distance to the river geometry. Figures 23 and 24 show the distance from the sensor and the position of the measuring cells in the horizontal axis
and the strength of the received (reflected) signal in the vertical axis.
From the "On-line" menu, select the "Start Range Check" option.
The following figures show typical curves obtained from range checks. To get a
better overview, you may remove individual curves by disabling the respective
checkboxes ([X] ➝ [ ]). It is recommended to display beams 1 and 2 only (disable
beams 3 and 4).
Fig. 22: Starting the range check.
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Figure 23 shows a test that provides an optimum result. For both acoustic beams,
the strength of the echo signal continuously decreases over the entire distance. The
increase obtained in cell #5 is caused by reflections from the opposite bank.
Therefore, only cells #1 through #4 should be used.
Please make sure that the last cell of the measured value ends at 80% of the
waterway width (based on the width in the mounting height of the sensor) to prevent interference from the opposite bank affecting the signal evaluation.
The red area in Figure 24 identifies those cells in which the reflected signal is too
weak to be evaluated. That means that even cell #5 does not provide usable data.
Furthermore, signal amplifications at 2.5 m and 10 m are indications of interference (e.g. obstructions).
Complete the test: From the "On-line" menu, select the "Stop Data Collection"
option.
Fig. 23: Successful range check.
Fig. 24: Range check failed.
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5 Operation
After completing all tests to be done during installation, the sensor is ready for use.
5.1 Disconnecting the PC from the sensor
Check whether the datalogger measurement interval is larger than the averaging
interval of the flow or level measurements (for the formula, refer to Chapter 4.2).
From the "Deployment" menu, select the "Start SDI-12 Mode" option.
Set the sensor address. The default address is "0". When the sensor is fitted
with an RS-422 interface, select "SDI-12 over RS-485".
Select the "Start" button.
Save the configuration to your PC.
Fig. 25: Starting SDI-12.
Fig. 26: Setting the SDI-12 address.
Fig. 27: Saving the deployment.
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In the subsequent window, the final parameterization of the sensor is dis-
played. Please check it carefully. Use the "Confirm" button to confirm the
configuration.
Now you have successfully configured the OTT SLD.
Use the "OK" button to disconnect the connection to the PC.
Also, physically disconnect the connection to the PC.
5.2 Connection to datalogger
Connect the sensor to the OTT netDL/OTT DuoSens using the SDI-12 interface
(refer to the
OTT netDL/OTT DuoSens Operating Instructions).
Fig. 28: Confirming the deployment.
Fig. 29: SDI-12 started.
1
2
5
6
7
8
3
4
0
4312
SDI-12 Data
SDI-12 GND
+ 12 V
GND
OTT DuoSens/
OTT netDL screw
terminal A/C
OTT SLD
RS-232
Supply
SDI-12
RS-232
Not used
Shielding
Fig. 30: Connecting the OTT SLD to
OTT DuoSens/OTT netDL using
the SDI-12 interface.
The GND connection represented by the
dashed line is necessary only in case the
OTT SLD/OTT netDL, and the OTT DuoSens
are powered by separate power supplies.
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Alternatively: Connect the sensor to the OTT DuoSens using the RS-485 inter-
face (SDI-12 protocol).
Alternatively: Connect the sensor to the OTT netDL using the RS-485 interface
(SDI-12 protocol).
The cables have a coded underwater connector. Attach it to the sensor. Please
observe all of the information from section 3.2 (use a silicone spray)!
5.3 Verifying the data
On the instantaneous value display of the OTT netDL/OTT DuoSens datalogger,
the OTT SLD instantaneous values are shown. Please note the time offset caused
by the configured intervals.
1
2
5
6
7
8
3
4
0
4312
+ 12 V
GND
Rx+
Rx–
Tx+
Tx–
RS-485 B
RS-485 GND
RS-485 A
OTT DuoSens
screw
terminal A
OTT SLD
RS-422
Supply
Not used
RS-422
RS-422
Shielding
Fig. 31: Connecting the OTT SLD to the
OTT DuoSens using the RS-485 interface
(SDI-12 via RS-485).
The GND connection represented by the
dashed line is necessary only in case the
OTT SLD and the OTT DuoSens are pow-
ered by separate power supplies.
1
2
5
6
7
8
3
4
0
4312
+ 12 V
GND
Rx+
Rx–
Tx+
Tx–
RS-485 B
RS-485 GND
RS-485 A
OTT netDL
screw
terminal C
OTT SLD
RS-422
Supply
Not used
RS-422
RS-422
Shielding
Fig. 32: Connecting the OTT SLD to the
OTT netDL using the RS-485 interface
(SDI-12 via RS-485).
The GND connection represented by the
dashed line is necessary only in case the
OTT SLD and the OTT netDL are powered
by separate power supplies.
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Appendix A
A.1 Technical Data
Supply voltage 12 … 16 V DC, typ. 12 V
Power consumption 50 … 500 mW (depending on measurement interval)
Flow velocity measurement
Measuring range –10 m/s ... +10 m/s
Accuracy 1 % of meas. value ±5 mm/s
Resolution 1 mm/s
Measurement averaging time 1 s … 3600 s
Number of measuring cells 9
OTT SLD 2.0MHz OTT SLD 1.0 MHz OTT SLD 0.6 MHz
Frequency 2 MHz 1 MHz 600 kHz
Blanking 0.1 … 8 m 0.3 … 15 m 0.5 … 30 m
Cell size 0.2 … 2 m 1 … 4 m 2 … 10 m
Range 10 m 25 m 80 m
Water level measurement (optional)
Measuring range 0.15 ... 10 m
Accuracy ±3 mm
Resolution 1 mm
Measurement averaging time 1 s … 3600 s
Minimum water depth above instrument 0.15 m
Pressure cell (optional) piezo-resistive
Measuring range 0 ... 10 m
Accuracy ±0.25 % FS
Resolution 1 mm
Internal memory
Capacity 9 MB (non-volatile)
Communication interfaces RS-232;
SDI-12 or SDI-12 via RS-485;
Modbus (optional)
Maximum cable length
RS-422/485 max. 500 m (9600 Baud)
RS-232/SDI-12 max. 65 m (9600 Baud /1200 Baud)
Operating temperature –5 °C ... + 35 °C
Storage temperature –20 °C … +70 °C
Protection class IP 68
Dimensions
Length 45 … 52.2 cm (depending on measuring frequency)
Diameter 7.5 cm (cylindrical)
Housing material POM
Plausibility check through status information
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A.2 Information on electromagnetic compatibility
Applicable to the European Union:
CAUTION: The OTT SLD is a Class A product (acc. to EN 61326-1:2006).
In a residential environment, the OTT SLD may create radio interference. In such
a case, the user must take appropriate actions to eliminate such interference.
A.3 Firmware update
Download a new version of the OTT SLD firmware from the www.ott.com
website (file: e.g. "SLD_V341_Midlife.bin").
Temporarily connect the OTT SLD to the PC using an RS-422/USB interface
converter (accessory) (RS-422 four-wire connection), as shown in Fig. 5. The
detailed wire assignment of the interface converter may be obtained from the
supplement sheet supplied.
Start the OTT SLD EasyUse software.
Enable the "Service mode" of the OTT SLD EasyUse software by simultaneously
pressing the keys "Ctrl + Alt + S".
Check communication as described in Chapter 3.3. For cable lengths from 50 m
long on, reduce the "Recorder/Upgrade baud rate" to 9600 baud.
From the "Updates" menu, select the "Firmware Upgrade …" option.
Select the current update file and then click on the "Open" button.
Select "OK" to confirm the safety question ➝ The OTT SLD EasyUse software
copies the new firmware into the OTT SLD.
Note
The settings saved in the OTT SLD are not lost after an update. However, the
measured values recorded will be lost!
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Appendix B – SDI-12 Commands and Responses
B.1 Basic commands
All SDI-12 basic commands are implemented in the OTT SLD. The following SDI-12 basic commands are relevant to the
operation of the OTT SLD:
Conventions applicable to measure value formats:
p – Sign (+,–)
b – Number before decimal point; output without leading zeros!
e – Number after decimal point
Command Response Description
a! a<CR><LF>
Acknowledgement active
a – Sensor address; factory setting = 0
aI! allccccccccmmmmmm …
… vvvxxxxxx<CR><LF>
Send identification
a – Sensor address
ll – SDI-12 protocol version
cccccccc – Manufacturer's identification (company name)
mmmmmm – Sensor identification
vvv – Sensor version (firmware)
xxxxxx – Serial number
OTT SLD response = 012OTT HACHSLD340123456 (example)
aAb! b<CR><LF>
Change sensor address
a – Old sensor address
b – New sensor address
?! a<CR><LF>
Query sensor address
a – Sensor address
"Velocity" measuring mode
aM! atttn<CR><LF>
and
a<CR><LF> after ttt seconds
Start measurement: Velocity in x direction
a – Sensor address
ttt – Time in seconds until the sensor has deter-
mined the measurement result.
OTT SLD response = averaging time set
(average interval) + 4 seconds
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Velocity in x direction
Measuring cell 1 … 9 [m/s]
Measured value format: pbb.eee
Range: –10.000 … +10.000m/s
aM1! atttn<CR><LF>
and
a<CR><LF> after 1 second
Start measurement: Water coverage, temperature,
pitch, roll, quality values
a – Sensor address
ttt – Time in seconds until the sensor has deter-
mined the measurement result.
OTT SLD response = 001;
averaging time set (average interval)
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
24
Page 25
Command Response Description
aD0! a<value1><value2><value3>...
…<value4><value5><CR><LF>
Send data
a – Sensor address
<value1> – Temperature [°C]
Measured value format: pbb.ee
Range: –6.00 … +40.00°C
<value2> – Combined water coverage from pressure measure-
ment and acoustic measurement (pressure measurement specifies the range in which the OTT SLD evaluates the acoustic measurement) [m]
Measured value format: pb.eee
Range: +0 … +9.999 m
<value3> – Water coverage for acoustic measurement [m]
Measured value format: pb.eee
Range: +0 … +9.999 m
<value4> – Quality value for pressure measurement [counts]
Measured value format: pbbb
Range: +0 … +255 counts
<value5> – Quality value for acoustic measurement [counts]
Measured value format: pbbb
Range: +0 … +255 counts
aD1! a<value6><value7><value8>…
…<value9><CR><LF>
<value6> – "Pass" values for acoustic measurement [%]
Measured value format: pbbb
Range: +0 … +100%
<value7> – Water coverage for pressure measurement [dbar]
Measured value format: pb.eee
Range: +0 … +9.999 dbar
<value8> – Pitch (Position of the instrument in transverse axis)
[0.1°]
Measured value format: pbb
Range: –25 … +25° (outside ➝ error bit)
<value9> – Roll (Position of the instrument in longitudinal axis)
[0.1°]
Measured value format: pbb
Range: –25 … +25° (outside ➝ error bit)
aM2! atttn<CR><LF>
and
a<CR><LF> after 1 second
Beam 1: Read signal amplitudes of the last measurement
a – Sensor address
ttt – Time in seconds until the sensor has provid-
ed the measurement result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Beam 1: Signal amplitude
Measuring cell 1 … 9 [counts]
Measured value format: pbbb
Range: +0 … +255 counts
aM3! atttn<CR><LF>
and
a<CR><LF> after ttt seconds
Start measurement: Velocity in y direction
a – Sensor address
ttt – Time in seconds until the sensor has
determined the measurement result.
OTT SLD response = averaging time set
(average interval) + 4 seconds
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
25
Page 26
26
Command Response Description
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Velocity in y direction
Measuring cell 1 … 9 [m/s]
Measured value format: pbb.eee
Range: –10.000 … +10.000m/s
aM4! atttn<CR><LF>
and
a<CR><LF> after 1 second
Beam 2: Read signal amplitudes of the last measurement
a – Sensor address
ttt – Time in seconds until the sensor has
provided the measurement result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Beam 2: Signal amplitude
Measuring cell 1 … 9 [counts]
Measured value format: pbbb
Range: +0 … +255 counts
aM7! atttn<CR><LF>
and
a<CR><LF> after 1 second
Read error messages and status values
a – Sensor address
ttt – Time in seconds until the sensor has
provided the measurement result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 2
a<CR><LF> – Service request
aD0! a<value1><value2><CR><LF>
Send data
a – Sensor address
<value1> – Refer to the description of the same
<value2> – command in "Discharge" measuring mode
"Discharge" measuring mode
aM! atttn<CR><LF>
and
a<CR><LF> after 1 second
Start measurement: Discharge, temperature, water coverage,
k*A factor, average flow velocity,
time spans, status value
a – Sensor address
ttt – Time in seconds until the sensor has
determined the measurement result.
OTT SLD response = averaging times set
(average interval) from "Flow" and "Level" +
5 seconds
n – Number of measured values
OTT SLD response = 2
a<CR><LF> – Service request
aD0! a<value1><value2><CR><LF>
Send data
a – Sensor address
<value1> – Currently calculated discharge value [m
3
/s]
Measured value format: pbbbb
Range: +0 … +9999 m
3
/s
<value2> – Currently calculated discharge value [l/s]
Measured value format: pbbb
Range: +0 … +999 l/s
Page 27
Command Response Description
aD1!
aD2!
a<value3><value4><value5>…
…<value6><CR><LF>
a<value7><value8><value9>…
…<CR><LF>
Send data
a – Sensor address
<value3> – Temperature [°C]
Measured value format: pbb.ee
Range: –6.00 … +40.00°C
<value4> – Water coverage [m]
Measured value format: pb.eee
Range: +0.000 … +9.999 m
<value5> – k*A factor [m
2
]
Measured value format: pbbbbb.e
Range: +0 … +99999,0 m
2
<value6> – Average flow velocity within the selected cell
range [m/s]
Measured value format: pb.eee
Range: –9.999 … +9.999m/s
<value7> – Time span between the last and current dis-
charge measurement – for service purposes
only!
<value8> – Time span up to the end of the measuring
interval (accumulated discharge) – for
service purposes only!
<value9> – Status value of the discharge measurement
– for service purposes only!
aM1! atttn<CR><LF>
and
a<CR><LF> after 1 second
Read accumulated discharge
a – Sensor address
ttt – Time in seconds until the sensor provides the
measurement result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 8
a<CR><LF> – Service request
aD0!
aD1!
a<value1><value2><value3>…
…<value4><CR><LF>
a<value5><value6><value7>…
…<value8><CR><LF>
Send data
a – Sensor address
Accumulated discharge:
<value1> – Partial value [10
8m3
]
Measured value format: pbbbb
Range: +0 … +9999 10
8m3
<value2> – Partial value [104m3]
Measured value format: pbbbb
Range: +0 … +9999 10
4m3
<value3> – Partial value [m
3
]
Measured value format: pbbbb
Range: +0 … +9999 m
3
<value4> – Partial value [l]
Measured value format: pbbb
Range: +0 … +999 l
Accumulated discharge of the last interval:
<value5> – Partial value [10
8m3
]
Measured value format: pbbbb
Range: +0 … +9999 10
8m3
<value6> – Partial value [104m3]
Measured value format: pbbbb
Range: +0 … +9999 10
4m3
<value7> – Partial value [m
3
]
Measured value format: pbbbb
Range: +0 … +9999 m
3
<value8> – Partial value [l]
Measured value format: pbbb
Range: +0 … +999 l
27
Page 28
Command Response Description
aM2! atttn<CR><LF>
and
a<CR><LF> after 1 second
Beam 1: Read signal amplitudes of the last measurement
a – Sensor address
ttt – Time in seconds until the sensor has
provided the result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Beam 1: Signal amplitude
Measuring cell 1 … 9 [counts]
Measured value format: pbbb
Range: +0 … +255 counts
aM3! atttn<CR><LF>
and
a<CR><LF> after 1 second
Start measurement: Pitch, roll, pressure
a – Sensor address
ttt – Time in seconds until the sensor has
determined the measurement result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 3
a<CR><LF> – Service request
aD0! a<value1><value2><value3>…
…<CR><LF>
Send data
<value1> – Pitch (Position of the instrument in transverse axis)
[0.1°]
Measured value format: pbb.ee
Range: –25.0 … +25.0°
<value2> – Roll (Position of the instrument in longitudinal
axis) [0.1°]
Measured value format: pbb.ee
Range: –25.0 … +25.0 °
<value3> – Water coverage for pressure measurement [dbar]
Measured value format: pb.eee
Range: +0 … +9.999 dbar
aM4! atttn<CR><LF>
and
a<CR><LF> after 1 second
Beam 2: Read signal amplitudes of the last measurement
a – Sensor address
ttt – Time in seconds until the sensor has
provided the result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex>
– Beam 2: signal amplitude
Measuring cell 1 … 9 [counts]
Measured value format: pbbb
Range: +0 … +255 counts
aM5! atttn<CR><LF>
and
a<CR><LF> after 1 second
Read unfiltered velocity in x direction
a – Sensor address
ttt – Time in seconds until the sensor has
provided the result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
28
Page 29
29
Command Response Description
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Velocity in x direction
Measuring cell 1 … 9 [m/s]
Measured value format: pbb.eee
Range: –10.000 … +10.000m/s
aM6! atttn<CR><LF>
and
a<CR><LF> after 1 second
Read unfiltered velocity in y direction
a – Sensor address
ttt – Time in seconds until the sensor has
provided the result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 9
a<CR><LF> – Service request
aD0!
aD1!
aD2!
a<value1><value2><value3><CR><LF>
a<value4><value5><value6><CR><LF>
a<value7><value8><value9><CR><LF>
Send data
a – Sensor address
<valuex> – Velocity in y direction
Measuring cell 1 … 9 [m/s]
Measured value format: pbb.eee
Range: –10.000 … +10.000m/s
aM7! atttn<CR><LF>
and
a<CR><LF> after 1 second
Read error messages and status values
a – Sensor address
ttt – Time in seconds until the sensor has
provided the result.
OTT SLD response = 001
n – Number of measured values
OTT SLD response = 2
a<CR><LF> – Service request
aD0! a<value1><value2><CR><LF>
Send data
a – Sensor address
<value1> – Error messages; 8-bit binary word
Example: "10000000"
Bit 1 … 8: 0 = O.K.
Bit 1: For service purposes only
Bit 2: 1 = Faulty measured values
Bit 3: 1 = Faulty sensor data (temperature, pitch,
roll, pressure)
Bit 4: 1 = Instrument internal error
Bit 5: 1 = Error in flash memory
Bit 6: For service purposes only
Bit 7: For service purposes only
Bit 8: 1 = Background noise above allowable
limit
<value2> – Status values; 8-bit binary word
Example: "01010000"
Bit 1: Instrument orientation
(for "Discharge" instrument version);
0 = Water level sensor directed upwards
1 = Water level sensor directed downwards
Bit 2: For service purposes only
Bit 3: 1 = Pitch outside the allowable value range
of ±25°
Bit 4: 1 = Roll outside the allowable value range
of ±25°
Bit 5 + Bit 6: 00 = Supply voltage too low,
01 = Power applied,
10 = Break, 11 = RTC alarm
Bit 7 + Bit 8: Driving power at the sound trans -
ducer; 00 = 0 (high), 01 = 1,
10 = 2, 11 = 3 (low)
Page 30
30
For more information on the SDI-12 basic commands, please refer to the publication SDI-12; "A Serial-Digital Interface
Standard for Microprocessor-Based Sensors; Version 1.2" (refer to the website "www.sdi-12.org").
B.2 Advanced SDI-12 commands
There are no SDI-12 advanced commands implemented in the OTT SLD.
Command Response Description
aV! atttn<CR><LF>
Perform system test
a – Sensor address
ttt – Time in seconds until the sensor provides
the result of the system test.
OTT SLD response = 000
n – Number of result values from system test
OTT SLD response = 0
a<CR><LF> – Service request
aD0! a<CR><LF>
Send data (after aV!)
a<CR><LF> – Service request
The OTT SLD does not perform the system test!
Page 31
Appendix C – OTT SLD and Modbus fieldbus protocol
Using a protocol converter, the OTT SLD may be connected to a fieldbus system
featuring RS-485 interfaces and Modbus protocol. For this purpose, OTT offer the
UNIGATE
®
CL-RS protocol converter as an accessory, which provides the necessary
script programming.
1
2
3
4
0
127
8
3
4
0
312 7645
Supply +
GND
UNIGATE
®
CL-RS
312 7645
RS-232
Supply
+
GND
Tx
Rx
Not used
SDI-12
RS-232
OTT SLD (max. 65 m)
312 7645
RS-422
Supply
+
GND
RS-422
Not used
RS-422
OTT SLD (max. 500 m)
312 7645
OTT netDL
screw
terminal C
RS-422
interface
(four-wire)
RS-422
interface
(four-wire)
Modbus
fieldbus
with
RS-485 +
GND
GND
RS-485 –
4312
RS-485 +
GND
RS-485 –
Rx-422 –
Tx-422 –
Rx-422 +
Tx-422 +
Rx+
Rx–
Tx+
Tx–
Fig. 33: Connecting the side looking Doppler
OTT SLD to the UNIGATE® CL-RS protocol
converter via RS-485 interface.
The GND connection represented by the
dashed line is necessary only in case the
protocol converter and the OTT netDL are
powered by separate power supplies.
31
Page 32
Installing the UNIGATE® CL-RS protocol converter
The UNIGATE
®
CL-RS is designed to be installed onto a standard C rail (TS 35).
The electrical connections are to be made as shown in Figure 33. The fieldbus system must be fitted with terminators at the front and back ends of the bus line. For
this purpose, two slide switches are provided to connect one terminator (RS-485) /
two terminators (RS-422) (for RS-485 (two-wire configuration): Rx-422 ➝ OFF;
Tx-422 ➝ ON).
Basic settings for Modbus operation
Measuring mode: (0x03) Read Holding Registers
Baud rate: 9600 bit/s
Data bits: 8
Parity: N
Stop bits: 1
Modbus address assignment
Use the rotary switches "S6" and "S7" to select a Modbus address between 0 and
255. It is a hexadecimal setting in which S6 is the high nibble and S7 is the low
nibble. Modbus addresses 0 (Broadcast) and 248 to 255 (reserved for internal
purposes) must not be used.
Example: S6 = 1; S7 = 2 ➝ 0x12 ➝ Modbus address 18.
Please note: Set the Modbus address only with power supply switched off!
(Any address change will be effective only after "PowerOn Reset" of the protocol
converter.)
Register allocation
Velocity values:
Address Data type Description
0 Word High byte: Minutes Low byte: Seconds
1 Word High byte: Day Low byte: Hour
2 Word High byte: Year Low byte: Month
3 Short Error code
4 Short Temperature [0.01°C]
5 Unsigned short Battery voltage [0.1V]
6 Unsigned short Speed of sound [0.1m/s]
7 Unsigned char Status
8 Unsigned short Not used
9 Unsigned short Not used
10 Short Velocity: x direction, cell #1 [mm/s]
11 Short Velocity: x direction, cell #2 [mm/s]
12 Short Velocity: x direction, cell #3 [mm/s]
13 Short Velocity: x direction, cell #4 [mm/s]
14 Short Velocity: x direction, cell #5 [mm/s]
15 Short Velocity: x direction, cell #6 [mm/s]
16 Short Velocity: x direction, cell #7 [mm/s]
17 Short Velocity: x direction, cell #8 [mm/s]
18 Short Velocity: x direction, cell #9 [mm/s]
19 Short Velocity: y direction, cell #1 [mm/s]
20 Short Velocity: y direction, cell #2 [mm/s]
21 Short Velocity: y direction, cell #3 [mm/s]
22 Short Velocity: y direction, cell #4 [mm/s]
23 Short Velocity: y direction, cell #5 [mm/s]
24 Short Velocity: y direction, cell #6 [mm/s]
25 Short Velocity: y direction, cell #7 [mm/s]
26 Short Velocity: y direction, cell #8 [mm/s]
27 Short Velocity: y direction, cell #9 [mm/s]
32
Page 33
28 Unsigned char Signal amplitude: Beam #1, cell #1 [counts]
29 Unsigned char Signal amplitude: Beam #1, cell #2 [counts]
30 Unsigned char Signal amplitude: Beam #1, cell #3 [counts]
31 Unsigned char Signal amplitude: Beam #1, cell #4 [counts]
32 Unsigned char Signal amplitude: Beam #1, cell #5 [counts]
33 Unsigned char Signal amplitude: Beam #1, cell #6 [counts]
34 Unsigned char Signal amplitude: Beam #1, cell #7 [counts]
35 Unsigned char Signal amplitude: Beam #1, cell #8 [counts]
36 Unsigned char Signal amplitude: Beam #1, cell #9 [counts]
37 Unsigned char Signal amplitude: Beam #2, cell #1 [counts]
38 Unsigned char Signal amplitude: Beam #2, cell #2 [counts]
39 Unsigned char Signal amplitude: Beam #2, cell #3 [counts]
40 Unsigned char Signal amplitude: Beam #2, cell #4 [counts]
41 Unsigned char Signal amplitude: Beam #2, cell #5 [counts]
42 Unsigned char Signal amplitude: Beam #2, cell #6 [counts]
43 Unsigned char Signal amplitude: Beam #2, cell #7 [counts]
44 Unsigned char Signal amplitude: Beam #2, cell #8 [counts]
45 Unsigned char Signal amplitude: Beam #2, cell #9 [counts]
Water coverage values:
Address Data type Description
46 Short Pitch [0.1°]
47 Short Roll [0.1°]
48 Unsigned short Water coverage for pressure measurement [mm]
49 Short Water coverage for acoustic measurement [mm]
50 Unsigned short Quality value for acoustic measurement [counts]
51 Unsigned short Speed of sound [0.1m/s]
52 Short Combined water coverage from pressure measure-
ment and acoustic measurement (pressure measurement specifies the range in which the OTT SLD
evaluates the acoustic measurement) [mm]
53 – Not used
54 – Not used
55 Short "Pass" values for acoustic measurement [%]
56 Short Temperature [0.01°C]
Discharge values:
Address Data type Description
Addresses 58 … 60: Date and time of the
currently calculated discharge value
57 Word High byte: Minutes Low byte: Seconds
58 Word High byte: Day Low byte: Hour
59 Word High byte: Year Low byte: Month
60 Unsigned short Currently calculated discharge value, the two MSBs
of a 32-bit value [l/s]
61 Unsigned short Currently calculated discharge value, the two LSBs
of a 32-bit value [l/s]
62 Unsigned short Accumulated discharge value, the two MSBs of a
48-bit value [l]
63 Unsigned short Accumulated discharge value, the two CSBs of a
48-bit value [l]
64 Unsigned short Accumulated discharge value, the two LSBs of a
48-bit value [l]
Please note:
After having connected the UNIGATE CL-RS protocol converter to the OTT SLD, you
have to start the OTT SLD operation mode "On-Line Data Collection" during commissioning:
Select the "Start Data Collection" option from the "On-line" menu of the
OTT SLD EasyUse Software.
33
Page 34
Appendix D – Representation of the discharge values in
"Discharge measurement" measuring mode
The measured values for instantaneous discharge as well as the accumulated discharge values may take large to very large
numerical values. Therefore, the OTT SLD splits the measured values into partial amounts that are weighed differently. In the
evaluation unit (alternatively in the datalogger as far as it is able to handle value ranges in the magnitude required), these
numerical values then have to be "reassembled" according to the mathematical algorithms given below.
D.1 Representation in SDI-12 protocol
Instantaneous discharge
Example: Q
inst
= 2 512.345 m³/s = 2 512 345 l/s
Split into two partial amounts in the aD0! response to the aM! command:
– <value1>: 2 512 m
3
/s (103 l/s)
– <value2>: 345 l/s (10
-3 m3
/s)
Q
inst
= <value1> + <value2> x 10–3 [m3]
= 2 512 + 345 x 10–3m³/s
= 2 512 + 0.345 m³/s
= 2 512.345 m³/s
Accumulated discharge and accumulated discharge from the last interval
Example: Q
inst
* = 2 500 m³/s = 2 500000 l/s Q
accumulated/24h
= 24 h x 3 600 s/h x 2 500 000 l/s = 217 066 608 000 l
Split into four partial amounts in the aD0! and aD1! responses to the aM1! command (aD0!: values 1 … 4; accumulated
discharge; aD1! : values 5 … 8; accumulated discharge from last interval):
– <value1>: 2 x 10
8 m3
(x 1011 l)
– <value2>: 1 706 x 10
4 m3
(x 107 l)
– <value3>: 6 608 m
3
(x 103 l)
– <value4>: 0 l (x 10
-3 m3
)
Q
accumulated/24h
= <value1> x 1011 + <value2> x 107 + <value3> x 103 + <value4> [l]
= 2 x 10
11
+ 1 706 x 107 + 6 608 x 103 + 0 l
= 200 000 000 000 + 17 060 000 000 + 6 608 000 + 0 l
= 217 066 608 000 l
or
Q
accumulated/24h
= ((<value1> x 104 + <value2>) x 104 + <value3>) x 103 + <value4> [l]
= ((2 x 104 + 1 706) x 104 + 6 608) x 103 + 0 l
= (21 706 x 10
4
+ 6 608) x 103 + 0 l
= 217 066 608 x 10
3
+ 0 l
= 217 066 608 000 l
* Assumption in example: Q
inst
is constant.
34
Page 35
D.2 Representation in Modbus protocol
Instantaneous discharge
Example: Q
inst
= 2 512.345 m³/s = 2 512 345 l/s
Decimal 2 512 345 l ➝ 0x26 55d9 l
Split into two partial amounts in one Modbus register each:
– Reg 60: 0x26 ➝ Decimal 38 ➝ Binary 0000000000100110
– Reg 61: 0x55d9 ➝ Decimal 21 977 ➝ Binary 0101010111011001
Q
inst
= reg 60 x 216 + reg 61 [l/s]
= 38 x 2
16
+ 21 977 l/s
= 2 490 368 + 21 977 l/s
= 2 512 345 l/s
or
Q
inst
= reg 60 << 16 ∨** reg 61 [l/s]
= 0000000000100110 ∨ 0101010111011001 l/s
32 17 16 1
= 00000000001001100101010111011001 l/s
= 2 512 345 l/s
<< = Shift operator to left-hand side: The bits are to be moved to left-hand side by the number of digits specified.
Accumulated discharge
Example: Q
inst
* = 2 500 m³/s = 2 500 000 l/s Q
accumulated/24h
= 24 h x 3 600 s/h x 2 500 000 l/s = 217 066 608 000 l
Decimal 217 066 608 000 l ➝ 0x32 8A2D 9580 l
Split into three partial amounts in one Modbus register each:
– Reg 62: 0x32 ➝ Decimal 50 ➝ Binary 0000000000110010
– Reg 63: 0x8A2D ➝ Decimal 35 373 ➝ Binary 1000101000101101
– Reg 64: 0x9580 ➝ Decimal 38 272 ➝ Binary 1001010110000000
Q
accumulated/24h
= reg 62 x 232 + reg 63 x 216 + reg 64 [l]
= 50 x 2
32
+ 35 373 x 216 + 38 272 l
= 214 748 364 800 + 2 318 204 928 + 38 272 l
= 217 066 608 000 l
or
Q
accumulated/24h
= ((reg 62 x 216) + reg 63) x 216 + reg 64 [l]
= ((50 x 2
16
) + 35 373) x 216 + 38272 l
= (3 276 800 + 35 373) x 65 536 + 38 272 l
= 3 312 173 x 65 536 + 38 272 l
= 217 066 608 000 l
or
Q
accumulated/24h
= reg 62 << 32 ∨** reg 63 << 16 ∨ reg 64
= 0000000000110010 ∨ 1000101000101101 ∨ 1001010110000000
48 33 32 17 16 1
= 000000000011001010001010001011011001010110000000
= 217 066 608 000 l
<< = Shift operator to left-hand side: The bits are to be moved to left-hand side by the number of digits
specified.
* Assumption in example: Q
inst
is constant.
** Logical operator OR
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Appendix E – Installation examples
The way how the OTT SLD is installed in a waterbody strongly depends on the local conditions. Installing the unit requires
individual planning, based on the particular station. For installing the unit, OTT offer various stainless steel brackets and slide
systems.
The following installation examples provide information on various installation options for an OTT SLD.
Sensor may be removed out of the water for service OTT SLD type
Example #1 – Installation at a staircase for water level measurement (mounting rail with slide) horizontal
Example #2 – Installation at a staircase for water level measurement (dual T rail with roller slide) horizontal
Example #3 – Installation at a natural river bank slope (mounting rail with slide) horizontal
Example #4 – Installation at a vertical edge wall (mounting rail with slide) horizontal or vertical
Sensor is fixed
Example #5 – Installation on a concrete base in the river bed horizontal
Example #6 – Installation at a sheet pile vertical
Example #7 – Installation at a vertical edge wall (mounting plate) horizontal or vertical
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E.1 Example #1 – Installation at a staircase for water level measurement (mounting rail with slide)
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E.2 Example #2 – Installation at a staircase for water level measurement (dual T rail with roller slide)
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E.3 Example #3 – Installation at a natural river bank slope (mounting rail with slide)
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E.4 Example #4 – Installation at a vertical edge wall (mounting rail with slide)
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E.5 Example #5 – Installation on a concrete base in the river bed
41
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E.6 Example #6 – Installation at a sheet pile
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E.7 Example #7 – Installation at a vertical edge wall (mounting plate)
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Document number
22.330.001.K.E 09-0419
OTT HydroMet GmbH
Ludwigstrasse 16
87437 Kempten · Germany
Phone +49 831 5617-0
Fax +49 831 5617-209
info@ott.com · www.ott.com
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