Technical Guide - Libelium · 2015-09-09 · precision in the measurement. ... The Efergy current...

waspmote

Smart MeteringTechnical Guide

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Index

Document version: v0.2 - 03/2012 © Libelium Comunicaciones Distribuidas S.L.

INDEX

0. General ................................................................................................................................................... 40.1. General and safety information ................................................................................................................................................40.2. Conditions of use ...........................................................................................................................................................................4

1. Hardware ................................................................................................................................................ 51.1. General Description ......................................................................................................................................................................51.2. Specifications ..................................................................................................................................................................................51.3. Electrical Characteristics ..............................................................................................................................................................5

2. Sensors ................................................................................................................................................... 62.1. Current Sensor (Efergy) ................................................................................................................................................................6

2.1.1. Specifications ...................................................................................................................................................................62.1.2. Measurement Process...................................................................................................................................................62.1.3. Socket .................................................................................................................................................................................7

2.2. Current Sensor (AT-B420L from LEM) ......................................................................................................................................72.2.1. Specifications ...................................................................................................................................................................72.2.2. Measurement Process...................................................................................................................................................72.2.3. Socket .................................................................................................................................................................................8

2.3. Load Cell (AME, AMT y AMS from Hanyu) ..............................................................................................................................82.3.1. Specifications ...................................................................................................................................................................82.3.2. Measurement Process...................................................................................................................................................92.3.3. Socket ............................................................................................................................................................................. 10

2.4. Liquid Flow Sensor (FS100A, FS200A, FS400 from Broil-Tech) .................................................................................... 102.4.1. Specifications ................................................................................................................................................................ 102.4.2. Measurement Process................................................................................................................................................ 112.4.3. Socket .............................................................................................................................................................................. 11

2.5. Ultrasonic Sensor (MaxSonar® from MaxBotix™) ............................................................................................................. 112.5.1. Specifications ................................................................................................................................................................ 112.5.2. Measurement Process................................................................................................................................................ 132.5.3. Socket .............................................................................................................................................................................. 14

2.6. Humidity Sensor (808H5V5) .................................................................................................................................................... 142.6.1. Specifications ................................................................................................................................................................ 142.6.2. Measurement Process .............................................................................................................................................. 142.6.3. Socket .............................................................................................................................................................................. 15

2.7. Temperature Sensor (MCP9700A) ......................................................................................................................................... 152.7.1. Specifications ................................................................................................................................................................ 152.7.2 . Measurement Process .............................................................................................................................................. 162.7.3. Socket .............................................................................................................................................................................. 16

2.8. Liquid Level Sensor (PTFA3415, PTFA0100, PTFA1103) ................................................................................................. 17

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2.8.1. Specifications ................................................................................................................................................................ 172.8.2. Measurement Process................................................................................................................................................ 172.8.3. Socket .............................................................................................................................................................................. 18

2.9. Luminosity Sensor (LDR) .......................................................................................................................................................... 182.9.1. Specifications ................................................................................................................................................................ 182.9.2. Measurement Process................................................................................................................................................ 192.9.3. Socket .............................................................................................................................................................................. 19

2.10. Displacement Foil Sensor (MTP sensor from Metallux and MagnetoPots from Spectra Symbol) ............... 192.10.1. Specifications ............................................................................................................................................................. 192.10.2. Measurement Process ............................................................................................................................................. 192.10.3. Socket ........................................................................................................................................................................... 21

2.11. Design and connections ........................................................................................................................................................ 212.11.1. Analog-to-Digital Converter ................................................................................................................................. 212.11.2. Socket 1 ........................................................................................................................................................................ 212.11.3. Socket 2 ....................................................................................................................................................................... 222.11.4. Sockets 3, 4 and 5 .................................................................................................................................................... 232.11.5. Sockets 6, 7 and 8 .................................................................................................................................................... 242.11.6. Sockets 9 and 12 ...................................................................................................................................................... 252.11.7. Sockets 10 and 13 .................................................................................................................................................... 262.11.8. Sockets 11 and 14 .................................................................................................................................................... 272.11.9. Frequency-to-Voltage Converter ....................................................................................................................... 28

3. Board configuration and programming ............................................................................................ 293.1. Hardware configuration ........................................................................................................................................................... 293.2. API ..................................................................................................................................................................................................... 29

4. Consumption ....................................................................................................................................... 334.1. Power control ............................................................................................................................................................................... 334.2. Tables of consumption .............................................................................................................................................................. 334.3. Low consumption mode .......................................................................................................................................................... 34

5. Maintenance ........................................................................................................................................ 34

6. Disposal and recycling ........................................................................................................................ 34

Index

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0. General

0. General

0.1. General and safety information • In this section, the term “Waspmote” encompasses both the Waspmote device itself and its modules and sensor boards. • Read through the document “General Conditions of Libelium Sale and Use”. • Do not allow contact of metallic objects with the electronic part to avoid injuries and burns. • NEVER submerge the device in any liquid. • Keep the device in a dry place and away from any liquid which may spill. • Waspmote consists of highly sensitive electronics which is accessible to the exterior, handle with great care and avoid

bangs or hard brushing against surfaces. • Check the product specifications section for the maximum allowed power voltage and amperage range and consequently

always use a current transformer and a battery which works within that range. Libelium is only responsible for the correct operation of the device with the batteries, power supplies and chargers which it supplies.

• Keep the device within the specified range of temperatures in the specifications section. • Do not connect or power the device with damaged cables or batteries. • Place the device in a place only accessible to maintenance personnel (a restricted area). • Keep children away from the device in all circumstances. • If there is an electrical failure, disconnect the main switch immediately and disconnect that battery or any other power

supply that is being used. • If using a car lighter as a power supply, be sure to respect the voltage and current data specified in the “Power Supplies”

section. • If using a battery in combination or not with a solar panel as a power supply, be sure to use the voltage and current data

specified in the “Power supplies” section. • If a software or hardware failure occurs, consult the Libelium Web Support section. • Check that the frequency and power of the communication radio modules together with the integrated antennas are

allowed in the area where you want to use the device. • Waspmote is a device to be integrated in a casing so that it is protected from environmental conditions such as light, dust,

humidity or sudden changes in temperature. The board supplied “as is” is not recommended for a final installation as the electronic components are open to the air and may be damaged.

0.2. Conditions of use • Read the “General and Safety Information” section carefully and keep the manual for future consultation. • Use Waspmote in accordance with the electrical specifications and the environment described in the “Electrical Data”

section of this manual. • Waspmote and its components and modules are supplied as electronic boards to be integrated within a final product. This

product must contain an enclosure to protect it from dust, humidity and other environmental interactions. In the event of outside use, this enclosure must be rated at least IP-65.

• Do not place Waspmote in contact with metallic surfaces; they could cause short-circuits which will permanently damage it.

Further information you may need can be found at http://www.libelium.com/waspmote.

The “General Conditions of Libelium Sale and Use” document can be found at http://www.libelium.com/legal.

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1. Hardware

1. Hardware

1.1. General DescriptionThe Smart Metering Board for Waspmote has been conceived to monitor those parameters that may require to be controlled in a domestic environment. It includes sensors for power and water consumption control, weight and liquid level measurement, displacement, luminosity and environmental humidity. Up to 14 sensors can be connected at the same time, all of them read through an analog-to-digital converter, communicated with the microprocessor through the I2C bus, that allows a higher precision in the measurement. The Smart Metering board is endowed with the electronics needed to use eight of the sensors (those on the sockets 1, 2, 3, 4, 5, 6, 12 and 10 or 11, thought for the current, load cell, liquid level, luminosity and flow sensors) to generate an alarm signal through an interruption in the mote when the measurement surpasses a determined threshold, implemented in a similar way to that in the Events Sensor Board.

1.2. SpecificationsWeight: 20grDimensions: 73.5 x 51 x 1.3 mmTemperature Range: [-20ºC, 65ºC]

Figure 1: Upper side

1.3. Electrical CharacteristicsBoard Power Voltages: 3.3V & 5VSensor Power Voltages: 3.3V, 5V, 10V and 24VMaximum admitted current (continuous): 200mAMaximum admitted current (peak): 400mA

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2. Sensors

2. Sensors

2.1. Current Sensor (Efergy)

2.1.1. Specifications

Maximum primary current: 90ATurns ratio: 1:1500 approximatelyMinimum resolution: 100mA approximately

2.1.2. Measurement Process

The Efergy current clamp is a low cost sensor that outputs a current proportional to the current in the primary circuit. That current (related with the primary current through a 1:1500 ratio) is converted into voltage through a variable load resistor that may be configured through a digital potentiometer in order to adapt the desired range of the measurement to the input range of the analog-to-digital converter. The functions implemented to configure and read the output value of the clamp are described in section 3.2.

Figure 3: Example of application with the current clamp sensor

Figure 2: Efergy current clamp

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2. Sensors

Figure 4: Example of application with the current clamp sensor

2.1.3. Socket

The clamp should be connected to the board through the power jack connector in socket 1, described in section 2.11.2.

2.2. Current Sensor (AT-B420L from LEM)


Maximum Current in primary (RMS): 5A-10A-20A-50A-100A-150AOutput Type: 4-20mASupply Voltage: +20V ~ +30VAccuracy: <±1.5%Linearity Error: <±0.5%Response Time: <100msTemperature Operation: -20ºC ~ 60ªCMinimum resolution: 100mA approximately


The AT-B420L series are a set of split core current clamps that differ from each other in the maximum primary current admitted (AT-5-B420L [0~5A], AT-10-B420L [0~10A], AT-20-B420L [0~20A], AT-50-B420L [0~50A], AT-100-B420L [0~100A] and AT-150-B420L [0~150A]). The sensor outputs a current between 4mA and 20mA proportional to the current through its primary circuit (4mA if there is no current, 20mA under the maximum current admitted by the clamp). This current is converted into voltage through a 100Ω resistor installed in the two connectors upon which the sensor can be placed. This voltage may be read through the analog-to-digital converter installed in the board. In figure 6 we can see a graph of the output of each clamp related to the current in its primary circuit.

Figure 5: AT-B420L Current Sensor

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2. Sensors

4 6 8 10 12 14 16 18 200

102030405060708090

100110120130140150

Output Current vs Input Current

AT-5-B420LAT-10-B420LAT-20-B420LAT-50-B420LAT-100-B420LAT-150-B420L

Output Current (mA)

Inpu

t Cur

rent

(A)

Figure 6: Graph of the outputs of the different models of current clamps

2.2.3. Socket

The AT-B420L sensor may be connected to the sockets 9 and 12, specifically implemented to hold 4-20 loop output devices. When connected to socket 12 the sensor may also be used to trigger an interruption to generate an alarm signal.

2.3. Load Cell (AME, AMT y AMS from Hanyu)


AMT:

Rate load: 3KgSensitivity: 2.0±0.1mv/VAccuracy grade: 0.02%F.SNonlinearity: ±0.02%F.SRecommended excitation voltage: +5VMaximum excitation voltage: +15VOperation temperature: -20ºC ~ +60ºC

AME:

Rate load: 50kgOutput sensitivity: 2.0±0.1mv/VAccuracy grade: 0.02%F.SNonlinearity: ±0.02%F.SRecommended excitation voltage: +9V ~ +12VOperation temperature: -20ºC ~ +60ºCProtection class: IP-65

Figure 7: AMT Load Cell

Figure 8: AME Load Cell

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2. Sensors

AMS:

Rate load: 600kgSensitivity: 2.0±0.1mv/VAccuracy grade: 0.02%F.SNonlinearity: ±0.02%F.SRecommended excitation voltage: +9V ~ +12VOperation temperature: -20ºC ~ +60ºCProtection: IP-65


The load cells used in the Smart Metering Board are single point cells with a Wheatstone bridge output in a full bridge configuration that requires connection to power supply, ground, positive output and negative output (red, black green and white wires respectively). The result is a differential voltage that is amplified and filtered to get an analog voltage proportional to the weight on the cell. In figure 11 the output voltage of the cell related to the load on it has been represented for three different models powered at 10V.

Figure 10: Example of application with the load cell

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 200

50

100

150

200

250

300

350

400

450

500

550

600

Output vs Load

AMS-600kgAMT-3000gAME-50kg

Output Voltage (mV)

Load

(kg)

Figure 11: Graph of the output of three models of load cells

Figure 9: AMS Load Cell

3kg

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2. Sensors

2.3.3. Socket

Any of the load cell models can be connected to socket 2 on the Smart Metering Board.

2.4. Liquid Flow Sensor (FS100A, FS200A, FS400 from Broil-Tech)


FS100A:

Flow rate: 0.15 ~ 2.5L/MinWorking voltage: +3.3V ~ +24VWorking temperature: -10ºC ~ 120ºCPulse number: 3900 pulses/literInlet pipe size: 2mmOutlet pipe size: 4mmAccuracy: ±0.5%Max rated current: 8mA

FS200A:

Flow rate: 0.5 ~ 25L/MinWorking voltage: +3.3V ~ +24VWorking temperature: -10ºC ~ 120ºCPulse number: 450 pulses/literPipe connection: ½’’Accuracy: ±1%Max rated current: 8mA

FS400:

Flow rate: 1 ~ 60L/MinWorking voltage: +3.3V ~ +24VWorking temperature: -10ºC ~ 120ºCPulse number: 390 pulses/literPipe connection: 1’’Accuracy: ±2%Max rated current: 8mA

Figure 12: Image of the Liquid FS200A Flow sensor

Figure 13: Image of the Liquid FS400 Flow sensor

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2. Sensors


The liquid flow sensors included in the Smart Metering Board output a signal that consists of a series of digital pulses whose frequency is proportional to the flow rate of the liquid through the sensor. That digital signal must be converted into an analog voltage to be read with the analog-to-digital converter. The frequency to voltage converter outputs an analog signal from 0V to 2.09V for an input square signal in the range between 0Hz and 1000Hz.

Figure 14: Example of application with the liquid flow sensor

2.4.3. Socket

The flow sensors may be connected on any of the sockets whose output may be selected as an input to the frequency-to-voltage converter, socket 10 if the sensor is to be powered at 3.3V or socket 11 if the sensor is to be powered at 5V. More information about the sockets and the frequency-to-voltage converter in sections 2.11.7, 2.11.8 and 2.11.9.

2.5. Ultrasonic Sensor (MaxSonar® from MaxBotix™)


XL-MaxSonar®-WRA1™:

Operation frequency: 42kHzMaximum detection distance: 765cmMaximum detection distance (analog output): 600cm (powered at 3.3V) - 700cm(powered at 5V)Sensitivity (analog output): 3.2mV/cm (powered at 3.3V) – 4.9mV/cm(powered at 5V)Power supply: 3.3 ~ 5VConsumption (average): 2.1mA (powered at 3.3V) – 3.2mA (powered at 5V)Consumption (peak): 50mA (powered at 3.3V) – 100mA (powered at 5V)Usage: Indoors and outdoors (IP-67)

Figure 15: Ultrasonic XL-MaxSonar®-WRA1 from MaxBotix™ sensor

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2. Sensors

Figure 16: Ultrasonic XL-MaxSonar®-WRA1 sensor dimensions

In the figure below we can see a diagram of the detection range of the sensor developed using different detection patterns (a 0.63cm diameter dowel for diagram A, a 2.54cm diameter dowel for diagram B, a 8.25cm diameter rod for diagram C and a 28cm wide board for diagram D):

Figure 17: Diagram of the sensor beam extracted from the data sheet of the XL-MaxSonar®-WRA1™ sensor from MaxBotix

LV-MaxSonar®-EZ0™:

Operation frequency: 42kHzMaximum detection distance: 645cmSensitivity (analog output): 2.5mV/cm (powered at 3.3V) – 3.8mV/cm(powered at 5V)Power supply: 3.3 ~ 5VConsumption (average): 2mA (powered at 3.3V) – 3mA (powered at 5V)Usage: Indoors

Figure 18: Ultrasonic LV-MaxSonar®-EZ0 from MaxBotix™ sensor

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2. Sensors

Figure 19: Ultrasonic LV-MaxSonar®-EZ0 sensor dimensions

In the figure below we can see a diagram of the detection range of the sensor developed using different detection patterns (a 0.63cm diameter dowel for diagram A, a 2.54cm diameter dowel for diagram B, a 8.25cm diameter rod for diagram C and a 28cm wide board for diagram D):

Figure 20: Diagram of the sensor beam extracted from the data sheet of the LV-MaxSonar®-EZ0™ sensor from MaxBotix


The MaxSonar® sensors from MaxBotix output an analog voltage proportional to the distance to the object detected. This sensor can be powered at both 3.3V or 5V, although the detection range will be wider for the last one.

In figure 21 we can see a drawing of an example application for the ultrasonic sensor: liquid level monitoring.

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2. Sensors

Figure 21: Example of application for the MaxSonar® sensor

The XL-MaxSonar®-WRA1™ sensor is endowed with an IP-67 casing, so it can be used in outdoor applications, such as liquid level monitoring in storage tanks.

2.5.3. Socket

Since this sensor may be powered at 3.3V or 5V, it can be placed on any of the sockets for analog sensors (10 and 13 for a 3.3V supply voltage, 11 and 14 for a 5V supply voltage).

2.6. Humidity Sensor (808H5V5)


Measurement range: 0 ~ 100%RHOutput signal: 0,8 ~ 3.9V (25ºC)Accuracy: <±4%RH (a 25ºC, range 30 ~ 80%), <±6%RH (range 0 ~ 100)Typical consumption: 0.38mAMaximum consumption: 0.5mAPower supply: 5VDC ±5%Operation temperature: -40 ~ +85ºCStorage temperature: -55 ~ +125ºCResponse time: <15 seconds


This is an analog sensor which provides a voltage output proportional to the relative humidity in the atmosphere. As the sensor’s signal is outside of that permitted at the input of the analog-to-digital converter installed in the Smart Metering Board, it’s output voltage has been adapted to a range of values between 0.4V and 1.95V.

Figure 22: Image of the 808H5V5 sensor

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2. Sensors

Figure 23: 808H5V5 humidity sensor output taken from the Sencera Co. Ltd sensor data sheet

2.6.3. Socket

This sensor may be connected to any of the sockets prepared for analog sensors powered at 5V, i.e. sockets 8, 11 and 14.

2.7. Temperature Sensor (MCP9700A)


Measurement range: -40ºC ~ +125ºCOutput voltage (0ºC): 500mVSensitivity: 10mV/ºCAccuracy: ±2ºC (range 0ºC ~ +70ºC), ±4ºC (range -40 ~ +125ºC)Typical consumption: 6μAMaximum consumption: 12μAPower supply: 2.3 ~ 5.5VOperation temperature: -40 ~ +125ºCStorage temperature: -65 ~ 150ºCResponse time: 1.65 seconds (63% of the response for a range from +30 to +125ºC)

Figure 24: Image of the MCP9700A temperature sensor

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2. Sensors

2.7.2 . Measurement Process

The MCP9700A is an analog sensor which converts a temperature value into a proportional analog voltage. The range of output voltages is between 100mV (-40ºC) and 1.75V (125ºC), resulting in a variation of 10mV/Cº, with 500mV of output for 0ºC. The voltage output may be directly captured by the analog-to-digital converter described in section 2.11.1.

Figure 25: Graph of the MCP9700A sensor output voltage with respect to temperature, taken from the Microchip sensor’s data sheet

2.7.3. Socket

Placing the MCP9700A sensor on socket 7 is recommended. Even though, since the sensor may be powered at 3.3V or 5V, it can be placed on any of the sockets for analog sensors.

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2. Sensors

2.8. Liquid Level Sensor (PTFA3415, PTFA0100, PTFA1103)


PTFA3415:

Measurement Level: HorizontalLiquids: WaterMaterial (box): PropyleneMaterial (float): PropyleneOperating Temperature: -10ºC ~ +80ºCMinimum consumption: 0uA

Figure 26: Image of the PTFA3415 sensor

PTFA0100:

Measurement Level: HorizontalLiquids: Heavy Oils and combustiblesMaterial (box): PolyamideMaterial (float): PolyamideOperating Temperature: -10ºC ~ +80ºCMinimum consumption: 0uA


PTFA1103:

Measurement Level: VerticalLiquids: WaterMaterial (box): PropyleneMaterial (float): PropyleneOperating Temperature: -10ºC ~ +80ºCMinimum consumption: 0uA



There are three liquid level sensors whose operation is based on the status of a switch which can be opened or closed (depending on its placing in the container) as the level of liquid moves the float at its end. The main differences between the three sensors, regarding its use in Waspmote, are to be found in their process for placing them in the container (horizontal in the case of the PTFA3415 and PTFA0100 sensors, vertical for the PTFA1103 sensor) and in the material they are made of (the PTFA1103 and PTFA3415 sensors recommended for edible liquids and certain acids and the PTFA0100 for heavy oil and combustibles, more specific information can be found in the sensors’ manual).

In the next figure, a number of examples can be seen of applications of liquid level monitoring with these sensors.

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2. Sensors

Figure 29: Examples of applications of liquid level monitoring.

2.8.3. Socket

Sockets 3, 4 and 5 have been implemented to be used with digital sensors such as the liquid level sensors, since they are directly connected to the OR gate, which allows direct interrupt triggering with digital signals without the necessity of configuring a comparison threshold.

2.9. Luminosity Sensor (LDR)


Resistance in darkness: 20MΩResistance in light(10lux): 5 ~ 20kΩSpectral range: 400 ~ 700nmOperating temperature: -30ºC ~ +75ºCMinimum consumption: 0μA approximately

Figure 30: Image of light sensor LDR

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2. Sensors


This is a resistive sensor whose conductivity varies depending on the intensity of light received on its photosensitive part. The measurement of the sensor is carried out through the analog-to-digital converter installed in th Smart Metering Board, reading the resulting voltage out of a voltage divider formed by the sensor itself and the load resistor of the socket upon which it has been connected.

The measurable spectral range (400nm – 700nm) coincides with the human visible spectrum so it can be used to detect light/darkness in the same way that a human eye would detect it.

2.9.3. Socket

This sensor has been thought to be placed on socket 6, specifically configured for it. It could also be connected to sockets 3, 4 and 5 for digital sensors, taking into account the variation of the load resistance and its effect on the interruption triggering.

2.10. Displacement Foil Sensor (MTP sensor from Metallux and MagnetoPots from Spectra Symbol)


Length: 200mmResistance range: 0 ~ 10kΩMinimum resolution: 1mm approximatelyConsumption: 0.33mA (sockets 10 and 13) ~ 1.6mA (sockets 11 and 14)

Figure 31: Image of the displacement sensor


The displacement sensors MagnetoPot from Spectra Symbol and MTP from Metallux are two potentiometers whose resistance changes in function of the position of a magnet (case of sensor the MagnetoPot) or the pressure exerted along its surface, so the value of its output voltage varies between 0V and the supply voltage that can be read through the analog-to-digital converter in the board.

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2. Sensors

Figure 32: Example of application for the displacement foil sensors

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 200

0,5

1

1,5

2

2,5

3

3,5

Output of the Foil Sensor

Vcc = 3V3Vcc = 5V

Wiper position (cm)

Out

put

Volta

ge (V

)

Figure 33: Graph of the output of the sensor for the 3.3V sockets (10 and 13) and the 5V sockets (11 and 14)

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2. Sensors

2.10.3. Socket

Both kind of sensors can be connected to any of the sockets for analog sensors described in sections 2.11.7 and 2.11.8 (sockets 10, 11, 13 and 14).

2.11. Design and connections

2.11.1. Analog-to-Digital Converter

Unlike other Libelium boards, where analog-to-digital converters have been installed only when the integration of a sensor required it, the Smart Metering Board has been endowed with an LTC2497 analog-to-digital converter from Linear Technology in order to improve the accuracy of the reading of all the sensors included. With the same purpose, a 4.5V voltage reference has been introduced (MAX6107 from Maxim Ic.), from which we get a range of measurement between 0 and 2.25V.

This analog-to-digital converter has a 16 bit resolution (which means a 68μV resolution) and a conversion time of 150ms, and communicates with the microprocessor through the I2C bus. All the functions to facilitate a transparent way of configuring and reading the converter have been implemented for the Waspmote API (described in section 3.2).

2.11.2. Socket 1

Socket 1 is composed of a power jack connector and the electronics needed to attach the low cost Efergy current clamp, described in section 2.1. The value of the load resistor upon which the output current of the clamp will flow may be modified through a digital potentiometer, varying between 39Ω y 10kΩ, so it can be adjusted in function of the range of the current to be measured. All the functions implemented to configure and read this socket are described in section 3.2.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_EFERGY); SensorSmart.setLoadResistor(40); SensorSmart.readValue(SENS_SMART_EFERGY);}

We can see an image of socket 1 in figure 34.

Figure 34: Picture of socket 1

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2. Sensors

2.11.3. Socket 2

Socket 2 has been design to connect single point load cells similar to that described in section 2.3. to the mote. Two power supply pins have been added, 5V and 10V, with the purpose of increasing the range of cells that can be connected to Waspmote. The output of the load cell, a Wheatstone bridge, is amplified using an instrumentation amplifier and filtered before its connection to the input of the analog-to-digital converter.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_24V_CONVERTER); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_LCELSS); SensorSmart.setAmplifierGain(1000); SensorSmart.readValue(SENS_SMART_LCELSS);}

In figure 35 we can see a picture of the socket in the boards. The function of each pin of the socket is indicated in it. Red wire of the load cell must be connected to the desired power supply, the black wire must be connected to the ground pin, the green wire corresponds with the positive output and the white wire with the negative output.

Figure 35: Picture of socket 2

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2. Sensors

2.11.4. Sockets 3, 4 and 5

Sockets 3, 4 and 5 have been conceived to connect up to three liquid level sensors and other similar sensor, such as Reed switches. They are composed of a strip of two pins, one of them connected to the 3.3V power supply and the other one connected to a load resistor of 10kΩ, so when the sensor is in an ‘open’ state the load resistor sets a logic zero (0V) at the input of the analog-to-digital converter, while in a ‘closed’ state the connection with the power supply sets a logic one (3.3V). This signal attacks directly the OR gate for interrupt triggering, so these sensors may be used to generate alarm signals without any other configuration.

These sockets can also be used with other types of sensors, such as resistive sensors, taking into account the effect that it may have on the interruptions if the logic one threshold is exceeded.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON,SENS_SMART_LIQUID1); SensorSmart.readValue(SENS_SMART_LIQUID1);}

In figure 36 we can see an image of the three sockets and an indication of the pin correspondence.

Figure 36: Picture of sockets 3, 4 and 5

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2. Sensors

2.11.5. Sockets 6, 7 and 8

These three sockets have been implemented to connect the humidity, luminosity and temperature sensors (808H5V5, LDR and MCP9700A respectively), already used in other Libelium boards. The first of them consists of a two pin strip that allows the connection of the LDR between the 3.3V power supply and a load resistor of 1kΩ, forming a voltage divider whose output may be read through the analog-to-digital converter and used to trigger an interruption when surpassing a comparison threshold configured through a digital potentiometer. Sockets 7 and 8 are thought to connect analog sensors powered at 3.3V and 5v respectively. The second one includes at its output a voltage divider composed of two 2.2kΩ resistors to adapt the output of the humidity sensor to the input range of the analog-to-digital converter.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_HUMIDITY); SensorSmart.readValue(SENS_SMART_HUMIDITY);}

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_TEMPERATURE); SensorSmart.readValue(SENS_SMART_TEMPERATURE);}

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_LDR); SensorSmart.readValue(SENS_SMART_LDR);}

We have an image of the sockets in figure 37, where the function of each pin has been indicated.

Figure 37: Picture of sockets 6, 7 y 8

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2. Sensors

2.11.6. Sockets 9 and 12

These two sockets allow the connection of any sensor that presents a 4-20 loop output, which means a current output between 4mA and 20mA. It consists of a two pin strip that facilitates the connection of the sensor to a 24V supply voltage and a load resistor of 100Ω and 0.1% tolerance that turns the current output by the sensor into a voltage between 400mV and 2V.

Socket 12 may also be used to trigger an interruption on the microprocessor of the mote when the voltage at the load resistor surpasses a threshold established by a digital potentiometer.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON, SENS_SMART_24V_CONVERTER); SensorSmart.setSensorMode(SENS_ON,SENS_SMART_4mA20_1); SensorSmart.readValue(SENS_SMART_4mA20_1);}

In the picture of figure 38 we can see both sockets and the pin correspondence for power supply and the load resistor.

Figure 38: Picture of sockets 9 and 12

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2. Sensors


Sockets 10 and 13 permit the connection of sensors powered at 3.3V. They consist of a three pin strip that facilitates the connection to power supply, ground and output voltage, and can be directly read with the analog-to-digital converter.

Socket 10 can also be used as an input to the frequency-to-voltage converter, described in section 2.11.9, so sensors that output a series of digital pulses, such as the flow sensors described in section 2.4, can be used to trigger interruptions or read directly with the analog-to-digital converter.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON,SENS_SMART_3V3_1); SensorSmart.readValue(SENS_SMART_3V3_1);}

In figure 39 both sockets and the correspondence of each of their pins are shown.


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2. Sensors


In a similar way to sockets 10 and 13, sockets 11 and 14 can be used to connect those sensors that must be powered at a 5V voltage. They consist of a three pin strip that permits the connection of the sensor to power supply, ground and output voltage, although in this case, in order to adapt the output range of the sensor to that of the analog-to-digital converter, a voltage divider composed of two 2.2kΩ resistors has been placed between the output of the sensor and the input of the converter.

The output of socket 11 may be used as input to the frequency-to-voltage converter, described in section 2.11.9, with the purpose of converting into an analog voltage the output of those sensors that present it as a series of digital pulses, so that it can be directly read with the analog-to-digital converter or used to trigger an interruption.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON,SENS_SMART_5V_1); SensorSmart.readValue(SENS_SMART_5V_1);}

In figure 40 we can see an image of both connectors and their pin correspondence.


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2. Sensors

2.11.9. Frequency-to-Voltage Converter

The frequency-to-voltage converter is an LM231 configured to output an analog voltage between 0V and 2.09V when the frequency of the input signal varies between 0Hz and 1000Hz.

The input signal may be selected through a jumper that allows user to choose between a sensor powered at 3.3V (socket 10) or a sensor powered at 5V (socket 11). If this circuit is not to be used, its supply voltage can be disconnected by removing a jumper.

The output of this stage can be read with the analog-to-digital converter or used to trigger an interruption when a threshold voltage, configured through a digital potentiometer, is surpassed.

Socket reading code

{ SensorSmart.setBoardMode(SENS_ON); SensorSmart.setSensorMode(SENS_ON,SENS_SMART_5V_1); SensorSmart.readValue(SENS_SMART_FV_CONVERTER);}

In figure 41 we can see an image of the circuit, where the jumpers for signal selection (socket 10 selected on the left, socket 11 selected on the right) and power connection are highlighted.

Figure 41: Frequency-to-voltage converter selection jumpers

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3. Board configuration and programming


3.1. Hardware configurationThe only hardware configuration needed by the user is that related to the sensor connection and the position of the power and input selection jumpers of the frequency to voltage converter circuit.

The right way to connect the sensors to their respective socket is shown in sections 2.11.2 to 2.11.8, dedicated to described each of the sockets of the board, while the position of the configuration jumpers of the frequency to voltage converter can be found in section 2.11.9.

3.2. APIThe functions to handle all the features of the board, included in the WaspSensorSmart API library, are detailed below:

SensorSmart.setBoardMode(MODE)

This function is used to manage the power supply applied to the Smart Metering board. Assigning the value SENS_ON to the variable MODE activates the Waspmote’s switches which allow the passage of the 3.3V and 5V voltages, while assigning SENS_OFF disconnects both switches cutting the power.

SensorSmart.setSensorMode(MODE, SENSOR)

This function, similar to setBoardMode, allows to activate or deactivate the power of each sensor independently.

The state on which the sensor should be set is defined through the variable MODE, which can take the values SENS_ON, to connect the power of the sensor, or SENS_OFF, to disconnect it.

The sensor, circuit or group of sensors that we are going to manage is stored in the variable SENSOR, that can take the following values:

• SENS_SMART_24V_CONVERTER, to activate the 24V DC-DC converter. • SENS_SMART_4mA20_1, to activate the 4-20 loop sensor on socket 9. • SENS_SMART_4mA20_2, to activate the 4-20 loop sensor on socket 12. • SENS_SMART_3V3_1, to activate the sensor on socket 10. • SENS_SMART_3V3_2, to activate the sensor on socket 13. • SENS_SMART_5V_1, to activate the sensor on socket 11. • SENS_SMART_5V_2, to activate the sensor on socket 14. • SENS_SMART_LDR, to activate the luminosity sensor on socket 6. • SENS_SMART_LCELLS, to activate the load cells. • SENS_SMART_EFERGY, to activate the Efergy current sensor. • SENS_SMART_TEMPERATURE, to activate the temperature sensor on socket 7. • SENS_SMART_HUMIDITY, to activate the humidity sensor on socket 8. • SENS_SMART_LIQUID1, to activate the liquid level sensor 1 (socket 3). • SENS_SMART_LIQUID2, to activate the liquid level sensor 2 (socket 4). • SENS_SMART_LIQUID3, to activate the liquid level sensor 3 (socket 5).

Take into account that to turn on the 4-20 loop sensors or the load cells the 24V DC-DC converter must be activated previously.

As said in section 4.1, the LDR, TEMPERATURE, HUMIDITY, LIQUID1, LIQUID2 and LIQUID3 sensors are controlled through the same switch, so when turning on or off one of them you will be acting on the whole group.

The 5V or 10v power supply for the load cells is selected through the variable SENS_SMART_LCELL_IN_USE, internal to the API of the board, that may take the values ‘1’ for 10V (chosen by default) or ‘0’ for 5V. This parameter may be modified in the file WaspSensorSmart.h (line 127).

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SensorSmart.setLoadResistor(RESISTOR)

This function allows user to configure the load resistor used to convert the output current of the Efergy sensor into a voltage that can be read by the analog-to-digital converter of the board. That resistor must be specified in the variable RESISTOR, expressed in ohms, and must take a real value between 39Ω and 10kΩ.

SensorSmart.setAmplifierGain(GAIN)

The function setAmplifierGain allows to choose the amplification gain that will be applied to the output voltage of the load cell with the purpose of adapting it to the range to be measured. The gain value is introduced through the variable GAIN in floating point format, and can be assigned values form 11 to 1000.

SensorSmart.readValue(SENSOR)

The function readValue may be used to execute the configuration, conversion and reading process of any of the sensors on the board through the analog-to-digital converter, resulting the whole I2C communication transparent to the user. In the variable SENSOR the sensor to be read is introduced. The values that can be assigned to this variable are:

• SENS_SMART_4mA20_1, to read the 4-20 loop sensor on socket 9. • SENS_SMART_4mA20_2, to read the 4-20 loop sensor on socket 12. • SENS_SMART_3V3_1, to read the sensor on socket 10. • SENS_SMART_3V3_2, to read the sensor on socket 13. • SENS_SMART_5V_1, to read the sensor on socket 11. • SENS_SMART_5V_2, to read the sensor on socket 14. • SENS_SMART_LDR, to read the luminosity sensor on socket 6. • SENS_SMART_LCELLS, to read the load cells. • SENS_SMART_EFERGY, to read the Efergy current sensor. • SENS_SMART_TEMPERATURE, to read the temperature sensor on socket 7. • SENS_SMART_HUMIDITY, to read the humidity sensor on socket 8. • SENS_SMART_LIQUID1, to read the liquid level sensor 1 (socket 3). • SENS_SMART_LIQUID2, to read the liquid level sensor 2 (socket 4). • SENS_SMART_LIQUID3, to read the liquid level sensor 3 (socket 5). • SENS_SMART_FV_CONVERTER, to read the output of the frequency-to-voltage converter.

SensorSmart.setThreshold(SENSOR, THRESHOLD)

This function is used to configure the comparison threshold that regulates the interrupt trigger from the Smart Metering Board. In the variable SENSOR the sensor whose comparison threshold is to be changed is introduced, taking the identifiers of the sensors that may generate an interrupt after a comparison as values (load cells, LDR, Efergy current clamp, 4-20mA loop sensor 2 and output of the frequency-to-voltage converter). In the THRESHOLD variable the value to be given to this threshold is introduced in floating point format (float), which must be within a range between 0 and 3.3V.

SensorSmart.attachInt()

The attachInt function, implemented as is in the code, including no parameters, enables interrupts generated by the board’s sensors, allowing the microprocessor to recognize and process them as such.

SensorSmart.detachInt()

Complementing the previous function, the aim of detachInt is to deactivate the interrupts if the microprocessor is not required to react in the event of a change in one of the sensors. After its execution the mote will ignore any interrupt which arrives from the sensors until the attachInt instruction is activated again.

SensorSmart.loadInt()

The loadInt instruction is used to read the content of the shift register and store its output in an integer variable called SensorSmart.intFlag, in which the sensor that has caused the interrupt and other sensors activated at that moment appear. Once all the registers have been read, they restart from zero, not loading again until a new interrupt triggers. To recognize if a sensor has produced an interrupt, it is sufficient to carry out a logic comparison between the identifier of the sensor and the intFlag variable.

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The sensors that may trigger an interrupt are the luminsity sensor, the load cell, the Efergy current clamp, the 4-20mA loop sensor 2, the frequency-to-voltage converter and the three liquid level sensors:

• SENS_SMART_LDR • SENS_SMART_LCELLS • SENS_SMART_EFERGY • SENS_SMART_4mA20_2 • SENS_SMART_FV_CONVERTER • SENS_SMART_LIQUID1 • SENS_SMART_LIQUID2 • SENS_SMART_LIQUID3

A basic program to detect events from the board will present a similar structure to the following, subject to changes in dependence of the application:

1. The board is switched on using the function SensorSmart.setBoardMode.

2. Initialization of the RTC using RTC.ON to avoid conflicts in the I2C bus.

3. Configuration of the thresholds of those sensors which may generate an interruption with function SensorSmart. setThreshold.

4. Activation of the sensors to generate given interruptions using function SensorSmart.setSensorMode.

5. Enable interruptions from the board using the function SensorSmart.attachInt.

6. Put the mote to sleep with the functions PWR.sleep or PWR.deepSleep.

7. When the mote wakes up, disable interruptions from the board using function SensorSmart.detachInt.

8. Load the value stored in the shif register with function SensorSmart.loadInt.

9. Process the interruption:

- Turn on those inactive sensors to be read using function SensorSmart.setSensorMode.

- Take the measurements needed using function SensorSmart.readValue.

- Turn off the sensors that shall not generate an interrupt with function SensorSmart.setSensorMode.

- Store or send via a radio module the gathered information.

10. Return to step 5 to enable interruptions and put the mote to sleep.

In the code bellow a complete example to read the temperature and current in function of the light presence is given:

/* ------------Smart Metering board example--------------- Testing the Smart Metering Board: Measurement of temperature and current in presence of light www.Libelium.com*/

// Set threshold here#defineTHRESHOLD2.0

// Maximum current measured by the sensor#defineMAX_CURRENT20

floatcurrent_value=0;floattemperature_value=0;

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voidsetup(){

//Switch on the board SensorSmart.setBoardMode(SENS_ON);delay(100);

// Init RTC RTC.ON(); delay(100);

//Configurethethresholdfortheluminositysensor SensorSmart.setThreshold(SENS_SMART_LDR, THRESHOLD);

//Turn on the LDR SensorSmart.setSensorMode(SENS_ON, SENS_SMART_LDR);}

voidloop(){ //Enable interruptions from the Smart Metering Board SensorSmart.attachInt(); //Put the mote to sleepPWR.deepSleep(“00:00:05:00”,RTC_OFFSET,RTC_ALM1_MODE1,UART0_OFF|UART1_OFF|BAT_OFF); //Disable interruptions from the sensor board SensorSmart.detachInt(); //Load the interruption register SensorSmart.loadInt();

current_value=0; if(SensorSmart.intFlag & SENS_SMART_LDR){//TurnontheDC-DCconverter SensorSmart.setSensorMode(SENS_ON, SENS_SMART_24V_CONVERTER); delay(50); //Turn on the current sensor on socket 9SensorSmart.setSensorMode(SENS_ON,SENS_SMART_4mA20_1); delay(50);//Readtherawvalueofthesocketcurrent_value=SensorSmart.readValue(SENS_SMART_4mA20_1);//CurrentconvesiontoAmperscurrent_value=MAX_CURRENT*(0.625*current_value-0.25); //Turn off the sensor on socket 9SensorSmart.setSensorMode(SENS_OFF,SENS_SMART_4mA20_1);//Turnoffthe24VDC-DCconverter SensorSmart.setSensorMode(SENS_OFF, SENS_SMART_24V_CONVERTER); } //Readtherawvalueofthetemperaturesensortemperature_value=SensorSmart.readValue(SENS_SMART_TEMPERATURE);//TemperatureconversiontoºCtemperature_value=(temperature_value-0.5)*100;

//SendthedatathroughtheXBeeXBee.setMode(XBEE_ON);XBee.begin(); delay(50);XBee.print(“Temperature:“);XBee.print(temperature_value);XBee.print(“Current:“);XBee.print(current_value); delay(50);XBee.close();XBee.setMode(XBEE_OFF);

}

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4. Consumption

4. Consumption

4.1. Power controlThe Smart Metering Board for Waspmote requires both the 3.3V and the 5V power supplies output from the mote. In the board itself a DC-DC converter is used to get the 24V voltage needed by the 4-20 loop sensors and the 5V and 10V voltage references for the load cells.

A combination of transistors and solid state switches is used to control independently the power supply of the components in the board and the sensors connected to it.

First of all, the sensors that have to be powered at 24V are controlled independently through a series of MOSFET transistors that may handle higher currents and voltages than those permitted at the solid state switches. This way, the DC-DC converter power supply can be controlled through the signal DIGITAL1, the 10V and 5V voltage references are powered using the signals ANALOG2 and ANALOG3 respectively, while the 4-20 loop sensors can be controlled by the signals DIGITAL5 (socket 9) and DIGITAL8 (socket 12).

The remaining sensors are controlled using solid state switches. The supply voltage of the electronics used to adapt the Efergy current clamp and the load cells is controlled through the same switch via signal ANALOG1, the humidity, luminosity, temperature and liquid level sensors (sockets 3, 4, 5, 6, 7 and 8), that require both 5V and 3.3V supplies, are controlled via signal ANALOG2, while at last the four analog sensors are independently controlled through signals DIGITAL3 (socket 10), DIGITAL7 (socket 11), DIGITAL6 (socket 13) and DIGITAL4 (socket 14).

All these switches may be controlled through the SensorSmart.setBoardMode and SensorSmart.setSensorMode functions implemented in the API. You can find more information about it in section 3.2.

4.2. Tables of consumptionIn the following table the consumption of the board is shown, the constant minimum consumption (fixed by the permanently active components) and the consumption of each of the independent blocks that may be powered independently. The board’s power can be completely disconnected, reducing the consumption to zero, using the 3.3V and the 5V main switches disconnection SensorSmart.setBoardMode command included in the library.

Consumption

Minimum (Constant) 300μA

24V DC-DC Converter 6mA

Frequency-to-Voltage Converter 7mA

Load Cell (5V) 300mA

Load Cell (10V) 500mA

4-20mA loop Sensors 60 ~ 350mA

Various Sensors Group (no sensors connected) 20μA

Liquid Level Sensors 0 ~ 330μA

Humidity Sensor 600μA

Temperature Sensor 5μA

LDR Sensor 100 ~ 1500μA

Flow Sensor (Requires Frequency-to-voltage Converter) 10mA

3.3V Sensors 10μA + Sensor Consumption

5V Sensors 10μA + Sensor Consumption

Efergy + Load Cell Electronics 1.4mA

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5. Maintenance

4.3. Low consumption modeThe Smart Metering Board has been designed to minimize the consumption of the mote in operation conditions as long as in low consumption modes:

• Avoid activating all the sensors at the same time: owing to the high consumption of some of the sensors of the Smart Metering Board, it is highly advisable, with the purpose of avoiding current peaks that exceed the maximum supported by the switches, avoid turning on many sensors at the same time, specially those that require the 24V DC-DC converter.

• Use the Waspmote low consumption mode: as the other sensor boards for Waspmote, the library of the Smart Metering Board includes all the functions needed to deactivate the sensors which are not being used and put the mote in low consumption mode.

• Do not connect senors that are not going to be used: since several sensors share the same power line, a sensor that is not going to be used connected to the board will entail an additional consumption, and so a shorter life of the battery.

5. Maintenance • In this section, the term “Waspmote” encompasses both the Waspmote device itself as well as its modules and sensor boards. • Take care with the handling of Waspmote, do not drop it, bang it or move it sharply. • Avoid putting the devices in areas of high temperatures since the electronic components may be damaged. • The antennas are lightly threaded to the connector; do not force them as this could damage the connectors. • Do not use any type of paint for the device, which may damage the functioning of the connections and closure mechanisms.

6. Disposal and recycling • In this section, the term “Waspmote” encompasses both the Waspmote device itself as well as its modules and sensor boards. • When Waspmote reaches the end of its useful life, it must be taken to a recycling point for electronic equipment. • The equipment has to be disposed on a selective waste collection system, different to that of urban solid waste. Please,

dispose it properly. • Your distributor will inform you about the most appropriate and environmentally friendly waste process for the used

product and its packaging.

Technical Guide - Libelium · 2015-09-09 · precision in the measurement. ... The Efergy current...

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Transcript of Technical Guide - Libelium · 2015-09-09 · precision in the measurement. ... The Efergy current...