OTT Pluvio 2 S User manual

English
Operating Instructions
Precipitation gauge
OTT Pluvio2S

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

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Table of contents
1 Scope of supply 4
2 Order numbers 4
3 Introduction 5
3.1 Measured value output to the SDI-12 and RS-485 interfaces 7
3.2 Measured value output at pulse output 9
3.3 Graphic display of measured value output for different precipitation intensities 11
3.4 Orifice ring rim heater 12
4 Basic safety information 15
5 Installing the OTT Pluvio2S 16
5.1 Recommended cable types/maximum cable lengths 16
5.2 Required tools and equipment 17
5.3 Preparing the installation location 18
5.4 Preparing the base plate 19
5.5 Preparing the connection cable 20
5.6 Installing the base plate on the pedestal 22
5.7 Connecting the connection cable 23
5.8 Connecting the grounding cable 23
5.9 Aligning the base plate 24
5.10 Performing final work 25
6 SDI-12 commands and responses 29
6.1 asic commands 29
6.2 Advanced SDI-12 commands 32
6.3 RS-485 command line mode (ASCII text retrieval) 35
7 Performing maintenance operations 36
7.1 Emptying the collecting bucket 36
7.2 Adding anti-freeze agent for winter operation 36
7.3 Performing the visual inspection 37
7.4 Additional checks in cases of defect 37
7.5 Troubleshooting/remedy 38
7.6 Performing the Guided Accuracy Test (check measurement) 42
8 Repair 44
9 Notes about the disposal of used units 44
10 Technical Data 45
Appendix A – Connecting the OTT Pluvio2S to an OTT datalogger 47
A.1 Connecting the OTT Pluvio2S to an OTT netDL or OTT DuoSens via SDI-12 or RS-485 interface 47
A.2 Connecting the OTT Pluvio2S to an OTT netDL or OTT DuoSens via the pulse output 49
Appendix B – Dimensions of the OTT Pluvio2S with pedestal and bottom plate 51
Appendix C – Dimensions of pedestal with bottom plate 52
Appendix D – Installing the anti-theft protection 53
Appendix E – Accessories/replacement parts 54

1 Scope of supply
䊳 OTT Pluvio2S – Weighing precipitation gauge;
collecting area: 200 cm2; capacity: 400 mm of precipitation.
Consisting of: base plate with weighing mechanism, bucket support,
collecting bucket, and pipe housing. With SDI-12, RS-485, and US
interfaces (for servicing purposes). Additional pulse outputs for amount
of precipitation and status information.
Optionally available with additional internal orifice rim heater.
– Installation accessory kit
(6 hexagon bolts M 8 x 30;
3 Phillips screws M 5 x 35
1 8-wire screw terminal strip;
1 6-wire screw terminal strip;
3 cable ties 140 x 3.6;
1 Jumper
1 open-ended wrench, size: 10/13
– US cable
US connector type A to US connector type , 3 m
– Operating Instructions
– Factory acceptance test (FAT) certificate
2 Order numbers
䊳 OTT Pluvio2S 70.030.002.9.0
䊳 OTT Pluvio2Sincl. internal orifice ring heater 70.030.001.9.0
For accessories and replacement parts, refer to Appendix E
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3 Introduction
The OTT Pluvio2S precipitation gauge is used for automatic determination of the
meteorological intensity and amount of precipitation.
In contrast to conventional precipitation gauges, the OTT Pluvio2S works using the
weighing principle. The OTT Pluvio2S reliably detects precipitation, whether liquid
or solid, by determining the weight of the collecting bucket. The OTT precipitation
gauge is characterized in particular by its low maintenance needs. This is achieved
by means of a high-capacity collecting bucket, the lack of a collection funnel as is
typical for tipping buckets, and the very robust design of the weighing mechanism.
A high-precision, stainless steel load cell, hermetically sealed against environmental
influences that remains stable over a long period, is used as the sensor element.
An integrated temperature sensor compensates for the temperature changes in the
weighing mechanism. The mechanical overload protection prevents damage to the
load cell from forces in a vertical direction higher than permitted, e.g. when emp-
tying the collecting bucket.
Fig. 1: OTT Pluvio2S precipitation gauge.
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Every 6 seconds, the precipitation gauge determines the weight of the collecting
bucket including its content using a resolution of 0.001 mm (= raw data). The
difference between this measured value and the basic weight of the empty collect-
ing bucket gives the current bucket content.
A special filter algorithm prevents incorrect measurement results in the process
from effects such as wind. The difference between the current bucket content and
the previous one gives the precipitation intensity in mm/min or mm/h.
These 6-second values for the precipitation intensity are added to the accumulated
precipitation amount (Accu total NRT – see below) by the OTT Pluvio2 S.
Depending on the filter algorithm run, the measured values are available as
real-time and non-real-time values:
䊳 Real-time output (RT): The OTT Pluvio2S outputs the measurement result
for intensities greater than 0.1 mm/min within a minute after occurrence of
the precipitation event. enefit: fast response time and precipitation output with
correct intensity.
䊳 Non-real-time output (NRT): The OTT Pluvio2S outputs the measurement
result 5 minutes after occurrence of the precipitation event. enefit: more
precise output with correct precipitation volume.
All measured values can be retrieved via a serial SDI-12 and RS-485 interface.
In detail, these are:
䊳 Intensity RT
䊳 Accu RT/NRT (since the last measured value sample)
䊳 Accu NRT (since the last measured value sample)
䊳 Accu total NRT (since the last reset)
䊳 ucket RT
䊳 ucket NRT
䊳 Temperature of load cell
䊳 Status OTT Pluvio2S (since the last measured value sample)
The OTT Pluvio2S provides the precipitation values using a resolution of 0.001 mm.
Individual response thresholds of ≥ 0.03 mm are applied to these values within
one hour. A detailed description of the individual measured values can be found
in Chapter 3.1.
The OTT Pluvio2S uses two pulse outputs to output the amount of precipitation
RT/NRT (output #1) as well as the status information (output #2) in parallel. The
pulse factor may be selected: one pulse equals 0.05 mm, 0.1 mm, 0.2 mm,
0.5 mm or 1.0 mm of precipitation.
Parallel operation of serial interface and pulse output allows two dataloggers or
one datalogger and one PLC to be connected simultaneously.
The OTT Pluvio2S is installed to a 2" pedestal the bottom plate of which is mounted
to a concrete foundation. The standard installation height is 1 meter (height of the
orifice ring rim). Alternatively, 1.2 or 1.5 meters are possible.
After connecting the supply voltage, the OTT Pluvio2S automatically starts measuring
operation (➝red LED is flashing, refer to Fig. 18). The OTT Pluvio2S is calibrated
in the factory. On site, no further calibration is necessary.
Any increases in weight greater than approx. 12 mm within 6 seconds are not output
as precipitation, as they exceed a natural level of precipitation. Thus, spurious increases
such as bucket changes or filling with anti-freeze are suppressed. Check measurements,
even with large reference weights (> 240 g), are possible using the values of ucket RT
and ucket NRT. The measured value sample is carried out in a joint data telegram with
multiple measured values. Individual samples with different intervals are not possible.
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For service purposes (test measurements, convenient setting of operating parame-
ters and for an accuracy test) a US interface has been provided. The particular
advantage of this is: when using the US interface, no separate power supply is
required.
Please note: After connecting the US interface, the OTT Pluvio2S interrupts
communication on the serial interfaces!
The measuring system of the OTT Pluvio2 S prevents output of any incorrect
precipitation amount and does not output any increases in precipitation through
the interfaces after the following situations:
䊳 US interface was connected (pipe housing removed)
for approx. 5 minutes
䊳 Emptying (large reduction in weight)
for approx. 5 minutes
䊳 Startup/power failure
for approx. 2 minutes
The OTT test weight kit (accessory) is used to perform annual check measurements
(guided accuracy test) in conjunction with the OTT Pluvio2operating software.
3.1 Measured value output to the SDI-12 and RS-485 interfaces
䊳 Intensity RT
Moving precipitation growth over the last minute before the sampling interval
(measuring method acc. to WMO Guideline No. 8). This measured value is
particularly suited, for example, for the exact determination of intensity with heavy
precipitation and for alarm management, but not for daily and monthly totals.
Output delay: Real-time output (RT)
Units: mm/h · mm/min
inch/h · inch/min
Threshold: 0,1 mm/min · 6 mm/h
Sampling interval required: 1 minute
Storing interval required: 1 minute
Note: Larger sampling intervals always give the precipitation intensity of the minute
just before the sampling interval! For precipitation intensities of < 0.1 mm/min, the
OTT Pluvio2S sets the output value to zero. Thus, this output value may not be used
for accumulating single intensity values.
䊳 Accu RT-NRT
This value is a combination of real-time and non-real-time output. This value pro-
vides the benefit of faster RT output together with subsequent non-real-time output
delivering the maximum accuracy possible. It shows the accumulated amounts of
precipitation over the sampling interval. If the amount of precipitation exceeds the
threshold, the OTT Pluvio2S outputs the measurement result in real time. Other-
wise, it collects the fine precipitation over a maximum of one hour and outputs the
measured value in non-real time. If the fine precipitation does not reach the
threshold within an hour, there will be no output. This measured value is similar to
the behaviour of a precipitation gauge with tipping bucket. This measured value is
particularly suited for daily or monthly totals and for alarm management.
Output delay: Real-time output (RT) for precipitation events
immediately exceeding the threshold, otherwise
non-real-time output (NRT).
Units: mm · inch
Threshold: 0.03 mm within an hour
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Recommended sampling interval: 1 minute (with simultaneous sampling of the
precipitation intensity)
Recommended storing interval: Any time between 1 minute and 24 hours. The
datalogger must total the individual measured
values using a summing function over the com-
plete storing interval!
Note: Every interface polling resets the total amount values in the OTT Pluvio2S
to zero!
䊳 Accu NRT
This measured value outputs the sum of the correct amounts of precipitation over
the sampling interval with a fixed output delay of 5 minutes. Due to better filter-
ing, this valuable provides a more precise precipitation sum. Fine precipitation is
col lected over a maximum of one hour and output after reaching the threshold. If
the fine precipitation does not reach the threshold within an hour, there will be no
output. This value is particularly suited for daily and monthly totals
Output delay: Non-real-time output (NRT)
Units: mm · inch
Threshold: 0.03 mm within an hour
Recommended sampling interval: 1 minute (with simultaneous sampling of the
precipitation intensity)
Recommended storing interval: Any time between 1 minute and 24 hours. The
datalogger must total the individual measured
values using a summing function over the com-
plete storing interval!
Note: Every interface polling resets the total measured value in the OTT Pluvio2S
to zero. The 5 minute output delay provides the option for climatological databases
to apply a timestamp correction when necessary.
䊳 Accu total NRT
This measured value outputs the sum of the correct amounts of precipitation since
the last device start with a fixed output delay of 5 minutes. For this purpose, the
individual Accu NRT values are totalled (redundant sensor). This value is particularly
suited for daily or monthly totals as well as for tracking the plausibility of the Accu
NRT and Accu RT-NRT values. enefit: No loss of the collected precipitation
amount values in case of temporarily disrupted data transfer.
Resetting this value is achieved
– by a separate SDI-12 reset command, or
– by switching the power supply on/off, or
– automatically if the measurement range (500 mm; 50 inch) is exceeded
Output delay: Non-real-time output (NRT)
Units: mm · inch
Threshold: 0.03 mm within an hour
Recommended sampling interval: 1 minute (with simultaneous sampling of the
precipitation intensity)
Recommended storing interval: Any time between 1 minute and 24 hours
(do not total/average measured values)
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䊳 Bucket RT
This value outputs the currently measured, unfiltered bucket content. It corresponds
to the measured weight raw data and is subjected to higher uncertainty with
regard to temperature and wind impact. The measured value is particularly suited
for quick reference measurements of the weighing mechanism and for determining
the current bucket level. Using this measured value for separately calculating the
amount of precipitation in an external datalogger is not reasonable!
Output delay: real-time output (RT)
Units: mm · inch
Resolution: 0.001 mm (1mm =
^20 g)
Recommended sampling interval: 1 minute (with simultaneous sampling of the
precipitation intensity)
Recommended storing interval: any time between 1 minute and 24 hours
(possibly averaging over 10 minutes)
䊳 Bucket NRT
This value outputs the currently measured, filtered bucket content.
It corresponds to the filtered weight value and is subjected to uncertainty with
regard to temperature impact. The value is particularly suited for determining
the content of the bucket and for calculating the evaporation behaviour. Using
this measured value for separately calculating the amount of precipitation in an
external datalogger is not reasonable!
Output delay: non-real-time output (NRT)
Units: mm · inch
Resolution: 0.001mm (1mm =
^20 g)
Recommended sampling interval: 1 minute (with simultaneous sampling of the
precipitation intensity)
Recommended storing interval: any time between 1 minute and 24 hours
䊳 Temperature of load cell
Internal temperature of the load cell for compensating for the temperature change.
This value is only relevant to internal purposes and generally differs from the current
ambient temperature by several °C.
Units : °C · °F
Recommended sampling interval: 1 minute (with simultaneous sampling of the
precipitation intensity)
Recommended storing interval: only as required (any time between 1 minute
and 24 hours)
3.2 Measured value output at pulse output
The OTT Pluvio2S uses two pulse outputs to output the amount of precipitation
RT/NRT (output #1) as well as the status information (output #2) in parallel.
Parallel operation of serial interface and pulse output allows two dataloggers
or one datalogger and one PLC to be connected simultaneously.
Electrical characteristics of the pulse and status outputs
Pulse ON contact closed
Pulse/pause ratio: 1:1
for 5 Hz =
^100/100 ms
for 2 Hz =
^250/250 ms
Contact design: non-bouncing, polarity independent, isolated
Current capacity, Imax : ≤ 100 mA (short-circuit proof;
load cut-off at 200 mA)
Voltage, Umax : ≤ 28 VDC
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䊳 Pulse-Accu RT-NRT
This measured value is same as Accu RT-NRT. However, the threshold is deter-
mined by the resolution of the pulse output (0.05 mm · 0.1 mm · 0.2 mm · 0.5
mm · 1.0 mm).
The measured value is output as a pulse sequence using a rate of 5 Hz (default)
or 2 Hz (con figurable through the OTT Pluvio2S operating software via US
interface).
Output delay: refer to Accu RT-NRT
Pulse factor (selectable): 0.05 mm · 0.1 mm · 0.2 mm · 0.5 mm · 1.0 mm
(1 mm =
^20 · 10 · 5 · 2 · 1 Impulse(s))
Resolution: 0.05 mm · 0.1 mm · 0.2 mm · 0.5 mm · 1.0 mm
Recommended sampling interval: continuous pulse counting
Recommended storing interval: any time between 1 minute and 24 hours
䊳 Pulse status information
This measured value corresponds to the current bucket level and additionally
shows status information. Moreover, status information may be used as an
alive signal.
0 pulses/min system error, device or cable at the pulse output faulty
(output #2)
10 … 100 pulses/min 0 … 100 % of the approx. bucket level
120 pulses/min maintenance by means of operation through US
Fig. 2: Pulse output circuit diagram.
The locations of the terminals
are shown in Fig. 13.
Output #1: Terminals #1 and #2.
Output #2: Terminals #3 and #4.
Pulse OUT mm/inch A
Pulse OUT mm/inch
B
Pulse OUT Status A
Pulse OUT Status B
1 2 34 Imax : 100mA*
Umax : 28 VDC
Terminals 2 + 4
Terminals 1 + 3
10 Ohm
Simplified schematic diagram
Detailed diagram
Terminals
internal optoelectronic relay
* short circuit protected; load cut-off at 200 mA
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Please note:
When the pulse outputs are connected to
– OTT dataloggers ➝no additional wiring is required to be made. You may
directly connect the pulse outputs to the pulse inputs of an OTT datalogger.
– Third-party datalogger ➝external wiring at the pulse and status outputs must
be designed in such a way, that the limits for Imax ≤ 120 mA and Umax ≤ 28 V
will be kept in all operating conditions! Use a pull-up resistor as applicable!
3.3 Graphic display of measured value output for different
precipitation intensities
Fig. 3: Schematic display of measured
value output for different precipitation
values of the OTT Pluvio2S for fine
precipitation (< 0.1 mm/min) and
precipiation (≥ 0.1 mm/min).
Thresholds of the channels
are indicated on the right.
Bucket RT
Bucket NRT
Intensity RT
Accu RT-NRT
Accu NRT
Accu total NRT
Fine precipitation
< 0,1 mm/min
Precipitation
≥0,1 mm/min
Pulse-Accu RT-NRT
5min
Threshold
0,001 mm
0,001 mm
0,1 mm/min
0,03 mm1)
0,03 mm1)
0,1 mm2)
1) within one hour 2) adjustable
0,03 mm1)
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3.4 Orifice ring rim heater
For the OTT Pluvio2S, an optional orifice rim heater is available. This heater
reliably keeps the orifice rim free of snow and ice at low ambient temperatures
(e.g. no snow or ice build-up). No snow will accumulate at the orifice rim.
The orifice rim heater consists of a ring-shaped heating element within the pipe
housing with temperature sensor and an electronic heater control module for con-
trolling and monitoring the heating function. The heater cable electrical connection
is established automatically via two plug contacts and a connector block once the
pipe housing is placed onto the base plate.
Only the orifice rim is heated to avoid unwanted losses caused by evaporation.
Therefore, the orifice rim heater does not prevent the contents of the collecting
container from freezing! The heater control unit reliably prevents a stack effect
(errors in precipitation measurement caused by thermal effects) by using a low
and continuously monitored orifice rim temperature.
Orifice rim
Pipe housing
Cable
Orifice rim heater
Plug contacts
Connector block
Fig. 4: Schematic diagram of
the OTT Pluvio2S orifice rim heater.
The surface shown in grey (orifice rim)
is the heated part of the pipe housing.
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The OTT Pluvio2S unit heats the orifice rim until the target temperature of +4 °C
(factory setting) is reached – as far as heating power and ambient conditions
allow. To achieve this, the heater control system measures both ambient and ori-
fice rim temperatures and uses these values together with the target temperature to
calculate the pulse/pause ratio. Depending on this value, the heater control system
supplies electricity to the heating element for 5 to 120 seconds.
In addition to this, several modes of operation provide the option of enabling/
disabling the heater control system based on certain criteria (see below).
When the heater control system is enabled, the OTT Pluvio2S unit continuously
performs a functional test for the orifice rim heater (heater self-test) to detect
potential error conditions. When the heater control system is temporarily disabled,
performing the heater self-test depends on the mode of operation set. The result is
used for system checks in the measuring area. In case the error cannot be correct-
ed (unusual operating conditions or faulty orifice rim heater), the "Heater function-
al check failed" status information is shown, refer to the response to the SDI-12
command aD2!, Chapter 6.1.
When the measured rim temperature exceeds 50 °C in heating mode, the rim
heater system triggers an automatic safety shutoff of the heating element.
The orifice rim heater can be switched ON/OFF using an advanced SDI-12 com-
mand or via a separate power supply. Thus, the orifice rim heater may completely
be switched OFF, for example in summer. In such case, a message is shown in the
Status Information (response to the SDI-12 command aD2!; value 8).
The nominal supply voltage for operating the orifice rim heater is 24 VDC, and the
maximum heating capacity with very low ambient temperatures is approx. 50
Watt. Optionally, the supply voltage of the orifice rim heater can be fed separate-
ly from or together with the supply voltage for the precipitation gauge.
As a special option, the orifice rim heater may be operated based on 12 VDC. In
this case, effective heating power is 25 % of the rated power. For operation in
moderate climate zones and using 12 V solar systems, this type of operation is
basically allowed. The data specified for 24 VDC operation cannot be maintained
across the entire temperature range (refer to Chapter 10, „Technical Data”). For
temperatures below –5 … –10 °C, snow or ice may adhere to the unit.
Orifice rim heater modes of operation:
䊳 Mode #0 Orifice rim heater is completely switched OFF.
(No heater self-test is performed).
䊳 Mode #1 Heater control system is continuously enabled.
The heater control system keeps the temperature of the orifice
rim at the preset target temperature.
(Factory setting)
䊳 Mode #2 Within a specified temperature range, the heater control system
is continuously enabled.
Same as Mode #1 with the heater control system temporarily
disabling the heater when the temperature is below an adjustable
temperature limit (–40 … +9 °C). elow the temperature limit, the
heater self-test is performed based on a selectable interval
(1 h … 7 d).
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䊳Mode #3 The heater is controlled based on the National Weather Service
(NWS) Standard. The heater control is active from a preset time
(starting time) on and continuously keeps the orifice rim tempera-
ture at the predetermined setpoint. The On-time may be adjusted
as well (1 … 1440 minutes).
Outside this On-time, the heater self-test is performed based on a
selectable interval (1 h … 7 d).
Please note: This mode requires the OTT Pluvio2S system time to be set cor-
rectly. In case a power failure lasts longer than 10 minutes, the OTT Pluvio2S
system time will be lost. This will result in incorrect heater control system opera-
tion!
䊳Mode #4 Heater control system is operated based on precipitation events.
Once precipitation has started, the heater control will be active
for a preset after-run time (1 ... 1440 minutes) and continuously
keep the orifice rim temperature at the predetermined setpoint.
Outside this after-run time, the heater self-test is performed based
on a selectable interval (1 h … 7 d).
Ambient temperature
Target temperature
Temporarily disabled (+064)
Heater control system status
Orifice rim temperature
t
Starting time*
* Factory setting: 14:00:00 o'clock
On-time
t
Fig. 5: Diagram of orifice
rim heater Mode #3.
Ambient temperature
Target temperature
Temporarily disabled (+064)
Heater control system status
Orifice rim temperature
Precipitation event
t
t
t
* Factory setting: 20 minutes
After-run time*
Fig. 6: Diagram of orifice
rim heater Mode #4.
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4 Basic safety information
䊳 Please read these Operating Instructions before using the OTT Pluvio2S for the
first time! Make yourself completely familiar with the installation and operation
of the OTT Pluvio2S! Keep these Operating Instructions for later reference.
䊳 The OTT Pluvio2S is used for automatic determination of the meteorological
precipitation intensity and amount of precipitation. Use the OTT Pluvio2S only
as described in these Operating Instructions!
For further information ➝see Chapter 3, „Introduction“.
䊳 Note all the detailed safety information given within the individual steps. All
safety information in these Operating Instructions is identified by the warning
symbol shown here.
䊳 Avoid heavy shaking and shocks during transport and operation!
The OTT Pluvio2S is equipped with a highly sensitive electronic weighing
mechanism. Only use the original packaging for transport!
䊳 Ensure the electrical, mechanical, and climatic specifications listed in the
technical data are adhered to.
For further information ➝see Chapter 10, „Technical Data”.
䊳 Carry out all recommended maintenance work at the frequencies specified.
See Chapter 7, „Carrying out maintenance work“.
䊳 Do not make any changes or retrofits to the OTT Pluvio2S! If changes or
modifications are made, any warranty will be void.
䊳 Have a defective OTT Pluvio2S checked and repaired only by the OTT repair
center. On no account carry out repairs yourself! Only a qualified repair
followed by a factory final test ensures the specified measurement accuracy.
For further information ➝refer to Chapter 8, „Repair“.
䊳 Properly dispose of the OTT Pluvio2S after taking out of service. On no account
put the OTT Pluvio2S into the normal household waste.
For further information ➝see Chapter 9, „Notes on the disposal of used units“.
15

5 Installing the OTT Pluvio2S
The installation of the OTT Pluvio2S is carried out on a 2" pedestal made of gal-
vanized steel (possible external diameter of pedestal 50 to 60.3 mm). The pedestal
must be securely attached to a concrete foundation having the appropriate dimen-
sions. The pedestals that are available from OTT as accessories are fitted with a
bottom plate designed for this purpose.
The standard installation height recommended by the World Meteorological
Organization, WMO, for precipitation gauges is 1 meter (height of bucket
orifice). Alternatively, an installation height of 1.2 or 1.5 m is allowed.
Carefully choose your setup location according to your meteorological require-
ments. At the same time, ensure the location is free of vibration. For example,
traffic on a nearby road can affect the measurement results through vibration.
The maximum distance to the data collection device and the power supply to
which the OTT Pluvio2S is to be connected depends on the interface used:
䊳 SDI-12 interface: 70 meters
䊳 RS-485 interface: 1000 meters
䊳 Pulse output: 1000 meters
For an OTT Pluvio2S with orifice rim heater, the maximum distance to the mains
adapter of the orifice rim heater is 125 meters.
Please note: The OTT Pluvio2S precipitation gauge is equipped with a highly
sensitive electronic weighing mechanism! Install the unit only as described in these
Operating Instructions. To avoid damage to the OTT Pluvio2S weighing mecha-
nism during installation: Avoid heavy shocks and large forces acting on the load
cell and the bracket for the bucket support (for these items, please refer to Fig. 8)!
5.1 Recommended cable types/maximum cable lengths
For operating the OTT Pluvio2S, the following connections have to be made:
䊳 power supply for the precipitation gauge,
䊳 power supply of the orifice rim heater (optional),
䊳 data collection device (SDI-12/RS-485 interface, pulse output),
䊳 ground terminal.
For the precipitation gauge power supply and the connection of the data collec-
tion device, a common connection cable can be used.
For an OTT Pluvio2S with orifice rim heater, an additional connection cable may
be used (alternatively two additional wires in the common connection cable).
enefit: The orifice rim heater can be switched on and off separately from the pre-
cipitation gauge. In addition, power consumption of the orifice rim heater requires
a larger wire cross-section to be used for longer connection cables.
In total, the connection area of the OTT Pluvio2S has two cable entrances (rubber
grommets).
Please note: The protection concept of the OTT Pluvio2S against overloads
is designed such that all overvoltages occurring are discharged via a ground
connection. For this, the proper and functional installation of a grounding cable is
absolutely necessary! This is connected to the OTT Pluvio2S at the ground terminal
and at the other end in the area of the data collection device or directly at the
OTT Pluvio2S to a concrete footing ground or ground rod.
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Please note: All connection cables must be UV-resistant and suitable to be laid
in the ground!
Connection cable for data collection device/precipitation gauge
SDI-12 interface – Cable length: maximum 70 m1)
– Cable type: shielded low-voltage cable
– Wire size: 3 x 0.5 mm2 2)
RS-485 interface – Cable length: maximum 1000 m
– Cable type: twisted-pair cable 3);
shielded design
– Wire size: 2 x 2 x 0.5 mm2
Pulse output – Cable length: maximum 1000 m
– Cable type: shielded low-voltage cable
– Wire size: 6 x 0.5 mm2
The connection cable recommended in each case includes the wires for power
supply and data collection device.
1)with a point-to-point connection (no SDI-12 bus operation), a cable length of up to 300 m is possible.
2) with standard SDI-12 wiring, alternative 4 x 0.5 mm2wire with separate power supply.
3) the wires intended for power supply can be twisted pair, but do not have to be.
Connection cable for orifice rim heater power supply 4)
– Cable length: maximum 125 m
– Cable type: unshielded low-voltage cable
– Wire size: 1… 25 m: 2 x 0,5 mm2
25 … 50 m: 2 x 1,0 mm2
50 … 75 m: 2 x 1,5 mm2
75 … 125 m: 2 x 2,5 mm2
Calculation is based on: output voltage of the 24 VDC power supply (e.g. mains
adapter)
4) optional: As necessary, alternatively provide two additional wires in the cable between data recording
unit and power supply considering adequate wire cross-section.
Grounding cable
– Cable length: max. 5 m
– Cable type: unshielded low-voltage cable
– Wire size: 1 x 10 mm2
USB cable
If any changes are to be made to the factory settings, a US cable is temporarily
required during commissioning (supplied). Maximum cable length: 3 m.
Please note: The US port has no overload protection. It is designed to be
temporarily used as a service interface.
5.2 Required tools and equipment
䊳 Open-ended wrench, size 13 mm (supplied)
䊳 Phillips screwdriver, size: PH 2
䊳 Slotted screwdriver, size: 0.8 mm x 4 mm and 1.0 mm x 6 mm
䊳 Tool for stripping insulation on electrical cables
䊳 Wire-cutting pliers
䊳 For a connection cable with wires made of strands: Ferrules and
crimping pliers
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5.3 Preparing the installation location
Please note: The depth of the concrete foundation should be determined by the
local conditions: The foundation must reach into the frost-free zone in the ground.
The dimensions given for the foundation depth are typical values for conditions in
Central Europe.
We recommend that an empty conduit pipe (with a wire for pulling in) for the
connection and grounding cables is incorporated into the concrete foundation.
䡵 Attach the pedestal with bottom plate to a concrete foundation measuring
approx. 45 x 45 x 80 cm using the “Mounting kit for 2" pedestal“ (refer to
accessories); refer to Fig. 7 and appendix .
Please note: The pedestal must be as vertical as possible!
䡵 Pull the connection cable for the data collection device/power supply into the
empty conduit pipe.
䡵 OTT Pluvio2S with orifice rim heater: As applicable, pull additional connection
cable for the orifice rim heater power supply into the empty conduit pipe.
䡵 In case the ground for the OTT Pluvio2S is implemented centrally in the area
of the data collection device: Also pull the grounding cable into the empty con-
duit pipe (alternatively, the ground is established directly at the OTT Pluvio2S
using a concrete footing ground or ground rod).
Connection cable
to data collection
device/power
supply
Pedestal with
bottom plate
Mounting kit
for 2" pedestal
(4 x)
Empty pipe
Grounding cable
Concrete
foundation
Fig. 7: The location prepared for
installing the OTT Pluvio2S.
For an OTT Pluvio2S with orifice
rim heater, an additional connection
cable may be used for supplying
power to the orifice rim heater.
The cables may alternatively be routed
outside of the pedestal. To protect the
cables (e.g. against animal bites), routing
the cables inside the pedestal is recom-
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5.4 Preparing the base plate
䡵 Carefully transport the OTT Pluvio2S to the installation location in the closed
shipping carton
䡵 Open the shipping carton and remove the acceptance certificate (FAT), the
polybag including installation accessories and possibly further existing
accessories.
䡵 Remove the pipe housing with collecting bucket and put it first aside.
䡵 Remove and open the inner carton (consider the hints on the carton) and
remove the shaped foam part
䡵 Remove the base plate from the inner carton and carefully place it on a flat
surface. Please note: Do not use the load cell or bracket for the bucket
support to lift the base plate!
Base plate
Bracket bucket support
Load cell
Highly sensitive
electronic weighing
mechanism – handle
with care!
Fig. 8: OTT Pluvio2S base plate.
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䡵 Unscrew 4 Phillips screws on the cover of the electronics unit approx. 3 mm,
raise the cover slightly and pull it off forwards. When the foam rubber seal
for the cover is stuck to the surface below, carefully pry the cover off using a
slotted head screwdriver.
5.5 Preparing the connection cable
Connection cable for data collection device/power supply:
䡵 Cut the connection cable so that it sticks out approx. 30 – 35 cm above the
pedestal. (The „excess“ cable can be stored in the pedestal later.)
䡵 Take the rubber grommet out of the electronics unit (see Fig. 13). Remove the
white blanking plug from the rubber grommet and push the grommet onto the
connection cable.
䡵 Strip off approx. 10 cm of the outer sheath of the connection cable.
䡵 Strip off approx. 5 mm of the insulation of the individual wires.
䡵 Put the cable shielding together and twist it.
䡵 For a stranded connection cable: push ferrules onto the wires and crimp using
crimping pliers.
䡵 Connect the cable to the supplied screw terminal strips (included in the poly-
bag); see Fig. 10 and 11:
– SDI-12 interface ➝ 8-wire screw terminal strip, contact 3
– RS-485 interface
2-wire ➝ 8-wire screw terminal strip, contacts 1/2
4-wire ➝ 6-wire screw terminal strip, contacts 5/6 +
8-wire screw terminal strip, contacts 1/2
– Pulse output ➝ 6-wire screw terminal strip, contacts 1/2
(Accu RT-NRT) + contacts 3/4
(pulse status information; as required)
– Power supply ➝ 8-wire screw terminal strip, contacts 6/7
(precipitation gauge) + contacts 5/8
(orifice rim heater; optional)
Orifice rim heater connection cable (optional)
䡵 If using a separate connection cable for the orifice rim heater: Assemble the
cable as described above and connect to the 8-wire screw terminal strip, see
Fig. 11.
Phillips screw
(4 x)
Electronic
unit cover Foam rubber seal
Fig. 9: Removing the cover
from the electronics unit.
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