OTT CBS User manual

English
Operating instructions
Bubble Sensor OTT CBS

We reserve the right to make technical changes and improvements without notice.

3
Table of Contents
1 Scope of supply 4
2 Order numbers 4
3 Introduction 5
3.1 Function 6
3.2 Status LED 6
4 Installing OTT CBS 7
4.1 Preparing the OTT CBS for installation 7
4.2 Fastening OTT CBS 7
4.3 Connecting measuring tube to OTT CBS 8
5 Installing bubble chamber 9
5.1 Installing bubble chamber for surface water 9
5.2 Installing bubble chamber for ground water 10
6 Connecting OTT CBS 12
6.1 Connecting power supply 13
6.2 Connecting the OTT CBS to any datalogger using an SDI-12 interface 13
6.3 Connecting the OTT CBS to any datalogger using a 4 … 20 mA interface 13
6.4 Connecting the OTT CBS to LogoSens 2 or DuoSens using an SDI-12 interface 14
6.5 Connecting the OTT CBS to LogoSens 2 or DuoSens using a 4 … 20 mA interface 16
7 Activating the purge function 18
8 Setting operating parameters using DIP switches 19
8.1 Setting the type of SDI-12 interface 19
8.2 Setting measurement type of the 4 … 20 mA interface to level or depth measurement 20
8.3 Scaling the measuring range for the 4 … 20 mA interface 20
8.4 Setting the measuring system for the 4 … 20 mA interface 21
8.5 Setting measurement type of the 4 … 20 mA interface to water 21
level or pressure measurement
8.6 Factory setting of the operating parameters 21
9 SDI-12 Commands and Response 22
9.1 Standard commands 22
9.2 Advanced SDI-12 commands 23
10 Determining the maximum load resistance at the 24
4 … 20 mA interface
11 Carrying out maintenance work 25
11.1 Activating purge function 25
11.2 Cleaning bubble chamber 25
11.3 Testing measuring tube 25
12
Status LED 26
13 Note about the disposal of old devices 26
14 Technical Data 27

1 Scope of supply
䊳OTT CBS –1 Bubble Sensor OTT CBS with possibility for connecting measuring tubes with
4 mm/2 mm external/internal diameter
–1 Installation kit (top hat rail with fastening parts; screw terminal blocks, pin jumpers)
–1 Operating Instructions
2 Order numbers
䊳OTT CBS Bubble Sensor OTT CBS 63.200.001.9.2
䊳Accessories Measuring tube
4 mm/2 mm external/internal diameter; transparent PE
– 50 m 99.420.050.9.5
– 100 m 99.420.100.9.5
Combined measuring tube/
bubble chamber suspension cable
black, with kevlar core for length stabilization, measuring tube
with 4 mm/2 mm external/internal diameter; transparent PE
– 50 m 99.420.009.9.5
– 100 m 99.420.008.9.5
Measuring tube
6 mm/4 mm with sheathing
Length as requested 20.500.133.5.5
Measuring tube
6 mm/4 mm without sheathing
Length as requested 20.500.302.5.5
Bubble chamber suspension cable
black, with Kevlar core for length stabilization
– 50 m 99.000.050.9.5
– 100 m 99.000.100.9.5
Bubble chamber for ground water
– for observation wells beginning at 2" diameter, 670 gram 55.510.051.4.2
Bubble Pot EPS 50 for surface water
– hose connector 4 mm/2 mm 55.510.048.3.2
– hose connector 6 mm/4 mm 55.510.049.3.2
Straight pipe fitting
– for connecting measuring tubes with 63.200.025.9.2
1/8" internal diameter and 3/8" external diameter
4

3 Introduction
The OTT CBS, working on the air bubble principle, can be used for measuring
ground water or water levels depending on the bubble chamber used.
To meet the various demands of the station, three different versions of the OTT
CBS bubble sensor are available:
Standard version:
䊳Measuring range 0 … 15 m or 0 … 1500 mbar
䊳Resolution 1 mm or 0.1 mbar
䊳Accuracy ±5 mm
USGS specification version:
䊳Measuring range 0 … 15 m or 0 … 1500 mbar
䊳Resolution 1 mm or 0.1 mbar
䊳Accuracy measuring range 0 … 15 ft: ±0.01 ft
measuring range 15 … 50 ft: ±0.065 % of measured value
or ±0.02 ft, whichever is less
30 m measuring range version:
䊳Measuring range 0 … 30 m or 0 … 3000 mbar
䊳Resolution 1 mm or 0.1 mbar
䊳Accuracy ±5 mm
The compressed air produced by a piston pump flows via a measuring tube and
the bubble chamber into the water to be measured. The pressure created in the
measuring tube is directly proportional to the water column above the bubble
chamber. The OTT CBS determines the barometric air and bubble pressure one
after the other. By taking the difference between the two signals, the OTT CBS
calculates the height of the water level above the bubble chamber.
The power supply can be provided from a mains adapter, battery or solar power.
The OTT CBS contains a purge function. This clears the measuring tube and the
bubble chamber of any minor contamination by pumping a large volume of air
into the measuring tube.
By using an intelligent pump strategy, no air drying unit is necessary for the
measuring range of 0 … 15 m.
Hose connection
for measuring tube
Air filter for
incoming air
DIP switch compartment
Status LED
Buttonfor activating
the purge unit
Terminal blocks A and B
for connecting the datalogger
and power supply
Fig. 1: Overview of OTT CBS.
5

For the display of any error states that may occur, the OTT CBS has a Status LED
(see Fig. 1).
Various operating parameters can be set using the eight DIP switches.
Bubble pot
EPS 50
Groundwater
bubble chamber
Measuring tube
Fig. 2: The main layout of a level
station with OTT CBS bubble sensor.
6

4 Installing OTT CBS
4.1 Preparing the OTT CBS for installation
䡵If necessary and you have not already done so: set operating parameters with
DIP switches (see Chapter 8).
4.2 Fastening OTT CBS
The OTT CBS is designed only to be installed on top hat rails (a section of top hat
rail is supplied with the OTT CBS). Choose a dry and dust free location for the
installation such as a gage station or control cabinet.
䡵First attach the OTT CBS on the upper edge of the top hat rail and then press
the underside against the top hat rail until it clicks into place.
Demounting OTT CBS
䡵First press one locking device downwards and pull the OTT CBS slightly for-
wards at this point. Press the second locking device downwards and remove
the OTT CBS upwards from the top hat rail.
Top hat rails Locking device
Fig. 3: Fastening the CBS on the top
hat rail (left)/demounting (right).
7

4.3 Connecting measuring tube to OTT CBS
To install the measuring tube on the OTT CBS, proceed as follows:
Measuring tube with 2 mm internal diameter
䡵Cut off the end of the measuring tube square with a sharp knife and push onto
the factory fitted connection nipple.
Maximum length of the measuring tube: 100 m.
Measuring tube with 4 mm internal diameter
䡵Cut off the end of the measuring tube square with a sharp knife.
䡵Remove cap nut (width across flats: 10) and pull off the (short) factory mounted
measuring tube from the connection nozzle.
䡵Push cap nut over the measuring tube (Ø 4 mm).
䡵Push measuring tube onto the connection nozzle.
䡵Push the cap nut back onto the connection nozzle and tighten by hand.
Maximum length of the measuring tube: 75 m.
Measuring tube with 1/8" internal diameter
A special pipe fitting for the 1/8" internal diameter measuring tube is available
(accessory). Please follow the instructions delivered with the pipe fitting for
installing the pipe.
Maximum length of the measuring tube: 100 m.
Pump
Cap nut
Connection
nozzle
Measuring tube
Ø: 4 mm
1.
2.
Connectionnipple
Measuring tube
Ø: 2 mm
Fig. 4: Connecting measuring
tube on OTT CBS.
8

5 Installing bubble chamber
Please ensure the following points are noted during installation:
䊳No contamination or moisture may be allowed into the measuring tube.
䊳When immersing the bubble chamber (only EPS 50), the OTT CBS must be
activated, so that the piston pump is operating during this process.
䊳Do not damage or kink the measuring tube during installation.
䊳Lay the measuring tube such that there is a continuous drop from the OTT CBS
towards the bubble chamber. Otherwise moisture could collect in a
hollow and
potentially block the tube with the formation of drops (see Fig. 5)
5.1 Installing bubble chamber for surface water
We recommend using the
Bubble Pot EPS 50 for measurements in surface waters.
See
Bubble Pot EPS 50 installation instructions for information on its installation.
1"metal tube
Directionofflow
"Bubble pot
EPS 50"
Measuring tube
Fig. 5: Routing requirements
for measuring tube.
9

5.2 Installing bubble chamber for ground water
To install the bubble chamber for ground water, proceed as follows:
䡵Determine depth of the bubble chamber (e.g. using a contact gauge). The
bubble chamber must be positioned under the lowest expected water level.
Depth = distance from bubble opening to upper edge of the
top cap
䡵Push the measuring tube into the cable gland of the bubble chamber as far as
it goes.
䡵Tighten the cable gland firmly by hand
䡵Cut suspension cable to length; suspension cable length = depth +
125 cm (to protect the suspension cable from being twisted off, it can be
melted, with a cigarette lighter for example).
䡵Feed the suspension cable through the hole in the bubble chamber as shown in
Figure 6 and tie firmly.
䡵Slide cover into position B (upwards), see Fig. 6.
Measuring pipe
Suspensioncable
bubble chamber
Metal pin
Cover in
positionA
Bubble openingCover in
positionB
Cable
gland
Hole
Bubble pot
Fig. 6: Installing bubble
chamber for ground water.
When lowering the bubble chamber, the
cover must be in position B! The cover
prevents water entering the measuring
tube during installation.
During initial startup, over pressure builds
up in the measuring tube. As a result, the
cover falls back to position A and opens the
measuring tube in the process.
10

䡵As shown in Fig. 7, attach the suspension cable of the bubble chamber to the
retainer on an OTT top cap already mounted. The retaining plate allows a fine
height adjustment afterwards.
䡵Secure the suspension cable against slipping with a knot.
䡵If top caps without retainers are used, ensure the suspension cable is attached
securely.
䡵Check all knots and attachments for correct position and firmness.
䡵Lower the bubble chamber slowly into the observation well with the suspension
cable.
䡵Feed the measuring tube out of the observation well through a hole.
Top cap
Retainer
Observation
well
Suspensioncable
bubble chamber
Securing knot
Retaining plate
Measuring tube
Fig. 7: Installing bubble chamber for
ground water – attaching suspension cable.
11

6 Connecting OTT CBS
The OTT CBS has the following interfaces
䊳SDI-12
䊳4 … 20 mA (current loop)
䊳RS-485, 2-wire (SDI-12 protocol via a physical RS-485 interface)
as well as a
䊳connection for the power supply (UBat + GND).
The three interfaces make it possible to connect the OTT CBS both to OTT data-
loggers and to any datalogger by another manufacturer that has the correct inter-
faces. The SDI-12 interface meets SDI-12 Standard 1.3 (SDI-12 = Serial-Digital
Interface with 1200 baud).
All electrical connections are made using two screw terminal strips (supplied) at
terminal blocks A and B on the underside of the OTT CBS.
4312 4312
+UBat
4 … 20 mA +
4 … 20 mA –
GND
RS 485 A*
RS 485 B*
SDI-12 DATA
SDI-12 GND
A B
Screw terminal strip
* SDI-12 protocol via physical
RS-485 interface (for connecting to
OTT LogoSens and OTT DuoSens)
Fig. 8: Assignments for the screw terminal
strips A and B of the OTT CBS.
12

6.1 Connect power supply
The OTT CBS requires a power supply of 10 … 30 V DC, typ. 12/24 V DC (e.g.
using batteries or mains connection with galvanically separated low safety voltage).
Please note the following points when dimensioning the power supply:
䊳Maximum power consumption per day: 3700 mAh (typ. 320 mAh/day) (with
1 min measurement interval and 100 m measuring tube using the 4 … 20 mA
interface)
䊳Peak current consumption: temporary max. 2 A
䊳Protect the supply voltage with a microfuse (e.g. 2.5 A, slow-blow)!
䊳When using solar panels, we recommend the use of an overvoltage protection
device.
To supply the OTT CBS with power, proceed as follows:
䡵Connect the power supply to screw terminal strip A of the OTT CBS as shown
in Fig. 8.
Notes
䊳The OTT CBS does not have a switch for switching the unit on and off. As soon
as power is supplied, the OTT CBS is ready for operation.
䊳Each time the power supply is attached, the piston pump operates for approx.
400 strokes (approx. 5 minutes running time).
6.2 Connecting the OTT CBS to any datalogger using an SDI-12
interface
䡵Connect the OTT CBS to an SDI-12 input of the external datalogger. Follow the
datalogger handbook as you do this. See Fig. 8 for the assignments.
6.3 Connecting the OTT CBS to any datalogger using 4 … 20 mA
interface
䡵Connect the OTT CBS to a 4 … 20 mA input of the external datalogger. Follow
the datalogger handbook as you do this as well as Chapter 10 of these instruc-
tions). See Fig. 8 for the assignments.
䡵With depth measurement: ensure that DIP switch 4 is set to ON.
13

6.4 Connecting the OTT CBS to LogoSens 2 or DuoSens using an
SDI-12 interface
Method A: Connect the OTT CBS via the SDI-12 interface (protocol and physical
interface: SDI-12). The maximum length of the cable is 70 m. Recommended
cable cross-section: 0.25 mm2:
䡵Connect the OTT CBS as shown in Figure 9 to the LogoSens 2 Station Manager
or to the DuoSens Compact Data Logger. Take note of the operating instructions
for the LogoSens 2/DuoSens.
Method B: Connect OTT CBS using the physical RS-485 interface (SDI-12 pro-
tocol via physical RS-485 interface). The maximum length of the cable is 1,500 m.
Recommended cable type: Unshielded twisted-pair cable; recommended cable
cross-section: 0.25 mm2:
䡵Connect the OTT CBS as shown in Figure 10 to the LogoSens 2 Station Manag-
er or to the DuoSens Compact Data Logger. Take note of the operating instruc-
tions for the LogoSens 2/DuoSens.
RS-485
input
A … R
4312
4312
LogoSens 2
RS-485
input
A
CBS
4312
4312
DuoSens
B
CBS
B
Fig. 10: Connecting the OTT CBS to
LogoSens 2 or DuoSens using an
RS-485 interface (SDI-12 protocol).
The letters above/below the screw terminal
strip identify the possible connections on
the LogoSens 2/DuoSens/CBS.
0 V
SDI-12
input
T
A … R
43124312
4312
LogoSens 2
SDI-12
input
A
CBS
4312
4312
DuoSens
B
CBS
B
Fig. 9: Connecting the OTT CBS to LogoSens
2 or DuoSens using an SDI-12 interface.
The letters above/below the screw terminal
strip identify the possible connections on
the LogoSens 2/DuoSens/CBS.
14

Configuring the LogoSens 2/DuoSens for the OTT CBS with SDI-12
interface
䡵Create a LogoSens 2/DuoSens channel with
SDI-12 Master or OTT SDI RS485
function block ( serial sensors tab).
䡵Apply the following settings:
䊳Terminal block LogoSens 2: A … R
DuoSens
SDI-12 Master : A 3-4 (specified)
DuoSens
OTT SDI RS485 : A 1-2 (specified)
terminal block used (screw terminal strip) of the
LogoSens 2/DuoSens.
䊳Slave address SDI-12 bus address. Each slave address may
only be allocated once to an SDI-12 bus line.
(checking/setting: see operating instructions
LogoSens 2/DuoSens, Chapter
SDI-12 transparent
mode
.) Typical setting: 0 (only one OTT CBS is con-
nected to the terminal block; no bus operation).
䊳Value no. Identifies which value (the xth of
n values) of the
OTT CBS is recorded in this channel. Typical set-
ting:
1 (first of seven values: level in [m])
䊳Measurement mode
M! (For the maximum 7 values of the OTT CBS).
䊳Allocation of the further four values of the OTT CBS
to virtual terminals (level in [cm]; level in [ft];
pressure in [mbar]; pressure in [psi]; temperature
in [°C]; status; see Chapter 9, command aM! and
aV! for further information).
䡵In the relevant
Channel function blocks, adjust to the required units and number
of digits after the decimal place (m: 3; cm: 0; ft: 3; mbar: 1; psi: 3; °C: 1;
status: 0).
Note: To record all seven values of an OTT CBS, seven channels in the
LogoSens 2/DuoSens are necessary. The first channel contains the function block
SDI-12 Master or OTT SDI RS485 as the input signal. The other channels each
contain a function block
Virtual Sensor (V02 to V07) as the input signal. Naturally,
just individual channels can be recorded. In this case, there are fewer entries
required in the
Value no./Virtual Terminal ID field.
Caution: The measuring time is at least 1 minute.
Value no./
Virtual Terminal ID
Fig. 11: Adjusting the operating parameters
of the LogoSens 2/DuoSens SDI-12 Master
function block.
The function block OTT SDI RS485
is set in the same way.
15

6.5 Connecting the OTT CBS to LogoSens 2 or DuoSens using a
4 … 20 mA interface
䡵Connect the OTT CBS to the LogoSens 2 Station Manager or to the DuoSens
Compact Data Logger as shown in Figure 12. Take note of the operating
instructions for the LogoSens 2/DuoSens. Maximum cable length/recommend-
ed cable cross-section: Ensure that the ohm cable resistance together with any
resistor present does not exceed the maximum permitted load resistance (see
Chapter 10)!
Configuring the LogoSens 2/DuoSens for OTT CBS with 4 … 20 mA
interface
䡵Create a LogoSens 2/DuoSens channel with function block
I 4-20 mA
(LogoSens 2) or U/I/Pt100/… (DuoSens) ( Analog sensors tab).
䡵Apply the following settings:
䊳Terminal block LogoSens 2: A … R
DuoSens: C ... F
terminal block used (screw terminal strip)
of the LogoSens 2/DuoSens.
䊳Measuring mode Set to
I 4-20 mA ext.
(only with DuoSens)
䊳Sensor lag time (s) switches on the LogoSens 2/DuoSens input
x seconds before the actual measurement
process; set to
1
Fig. 13: Setting operating parameters of the
LogoSens 2 I 4-20 mA function block.
The DuoSens function block
U/I/Pt100/…
is set in the same way.
4 … 20 mA
input
A … R
4312
4312
LogoSens 2
4 … 20 mA
input
C … F*
CBS
4312
4312
DuoSens
A
CBS
A
100 Ohm
resistor
* DuoSens with
analog extensiononly
+UBat
GND
+UBat
GND
Fig. 12: Connecting the OTT CBS to
LogoSens 2 or DuoSens using a
4 … 20 mA interface.
Use the 100 Ohm OTT resistor
(order number: 55.550.126.4.2)!
The letters above/below the screw terminal
strip identify the possible connections on the
LogoSens 2/DuoSens/CBS.
In the shown application the supply of the
current loop will occur via the OTT CBS.
16

䊳if required: record error codes if range
overflow
䊳not required with an OTT CBS
䡵Insert a function block
2-Point scaling into this channel and set the appropriate
water levels for the electrical values measured (e. g. for an OTT CBS with 15 m
measuring range and level measurement (DIP switches 5 + 6 = ON):
Point 1: 4 →0; Point 2: 20 →15). Ensure you note here the settings of DIP
switches 5 + 6!
䡵With depth measurement: ensure that DIP switch 4 is set to ON or carry out the
inversion of the value via function
2-point scaling (e.g. for an OTT CBS with
15 m measuring range and depth measurement (DIP switches 5 + 6 = ON):
Point 1: 4 →15; Point 2: 20 →0).
䡵In the relevant
Channel function block, set the unit and number of digits after
the decimal place (m: 3; cm: 0; ft: 3; mbar: 1; psi: 3).
Note on points 6.2 to 6.5
䊳To reference OTT CBS level/depth values to a level zero: Input the contact
gauge/staff gauge measurement, for example using the scaling function of the
datalogger connected to the OTT CBS (e.g. LogoSens/DuoSens).
Auxiliary sensor supply via
relay contact at terminal block
(only for LogoSens 2)
□Error code if range overflow
17

7 Activating the purge function
On the front of the OTT CBS there is a Pump membrane button (see Fig. 14).
Pressing the button activates the purge function for as long as it is pressed. The
Status LED lights for approx. 2 seconds. With an activated purge function, the
CBS pumps a large amount of air through the measuring tube for the required
time period (see also Chapter 11). The purge function can also be activated via
an SDI-12 command.
Note: Press the membrane button for at least one second as otherwise the error
memory is called and displayed at the
Status LED.
Pump
CBS
Membrane button
Fig. 14: Activating purge function manually
on the OTT CBS with membrane button.
18

8 Setting operating parameters using DIP switches
The eight DIP switches are behind a cover on the underside of the OTT CBS
(see Figure 1). The following operating parameters can be set with them:
䊳DIP 1, 2, 3 Setting the type of SDI-12 interface
䊳DIP 4 Setting measurement type as level or depth measurement*
䊳DIP 5 + 6 Scaling measuring range *
䊳DIP 7 Setting metric or imperial system (m/mbar or feet/psi) *
䊳DIP 8 Setting measurement type as water level or pressure measure-
ment *
*these settings only affect the 4 … 20 mA interface.
8.1 Setting the type of SDI-12 interface
With DIP 1 … 3 select the type of SDI-12 interface of the OTT CBS (screw terminal
strip B; contacts 1 to 4). Please also take note that only one of the interfaces can
be used in each case: 4 … 20 mA or SDI-12 (no parallel operation of the inter-
faces).
Possible types for the SDI-12 interface
䊳Standard SDI-12 interface (protocol and physical interface: SDI-12)
䊳SDI-12 via RS-485 interface without termination (SDI-12 protocol via
physical RS-485 interface).
Use this setting if multiple OTT CBS are connected in parallel to one RS-485
cable (bus operation) for all OTT CBS except the last device at the end of the
bus.
䊳SDI-12 via RS-485 interface with termination (SDI-12 protocol via physical
RS-485 interface).
Use this setting if
– multiple OTT CBS are connected in parallel to the RS-485 cable (bus
operation) for the last device at the end of the bus, or if
– only one OTT CBS is connected to the RS-485 cable.
ON
12345678
ON
12345678
ON
12345678
SDI-12 interface
SDI-12 via RS-485 interface
without termination
SDI-12 via RS-485 interface
with termination
Fig. 15: Setting the type of SDI-12
interface of the OTT CBS.
19

8.2 Setting measurement type of the 4 … 20 mA interface to
level or depth measurement
8.3 Scaling the measuring range for the 4 … 20 mA interface
With DIPs 5 and 6 you can scale the available measuring range (15 or 30 m) of
an OTT CBS to a smaller range. Where the whole measuring range is not required,
this has the advantage that a higher resolution for the 4 … 20 mA interface can
be achieved. Example: For 2 m water level change 16 mA measuring range is
available (DIP switches 5 + 6 = OFF).
ON
12345678
ON
12345678
ON
12345678
ON
12345678
15 m/ 50 ft
1.5 bar / 25 psi
(not scaled)
30 m/ 100 ft
3 bar / 50 psi
(not scaled)
8 m/ 25 ft
0.8 bar / 12 psi
15 m/ 50 ft
1.5 bar / 25 psi
4 m/ 12 ft
0.4 bar / 6 psi
8 m/ 25 ft
0.8 bar / 12 psi
2 m/ 6 ft
0.2 bar / 3 psi
4 m/ 12 ft
1.5 bar / 6 psi
Standard +
USGS specification
30 m measuring
range
CBS version
Fig. 17: Scaling the measuring
range of the OTT CBS
(4 … 20 mA interface).
ON
12345678
ON
12345678
Level Measurement
Depth Measurement
Fig. 16: Setting measurement type level or
depth measurement of the OTT CBS
(4 … 20 mA interface).
20