A Data Logger for Wireless Sensor Network

Giuseppe Amato

, Stefano Chessa

, Claudio Gennaro

, Daniele Pallini

and Claudio Vairo

ISTI-CNR, via G. Moruzzi 1, Pisa, Italy

Universit`a di Pisa, Largo B. Pontecorvo 3, Pisa, Italy

Keywords:

WSN, Logger, Transducer, Java.

Abstract:

Wireless sensor networks (WSN) are often used to monitor environmental data because of their low cost.

However, writing applications for such a technology requires not trivial programming skills. Moreover it is

not easy to ﬁnd available general purpose tools that can be used to perform a monitoring task with a WSN

because usually such tools are focused on a speciﬁc application scenario. In this paper we present a tool for

the real-time acquisition of data from a set of Mote sensors and for the storage of the acquired data in the ﬂash

memory of the sensors. The tool provides functionalities to retrieve the stored data in the sink node, to insert

them in a database and to visualize them by means of a graphical user interface that runs on a linux-based PC.

The tool that we propose consists of both the software that runs on the PC and the software to be installed on

Motes.

1 INTRODUCTION

Wireless sensor networks (WSN) are a technology

suitable to monitor a wide range of environmental pa-

rameters such as pressure, temperature, acceleration,

chemical composition, etc... and they are used for

battleﬁeld surveillance, habitat monitoring, home au-

tomation and health-care applications (Baronti et al.,

2007; Culler et al., 2004; Romer and Mattern, 2004).

Monitoring/Logging services, in particular, focus

on dissemination and collection of environmentaldata

in order to monitor the ﬂora, the fauna as well as nat-

ural and human-made elements. For example, (Ya-

mamoto et al., 2012) provides an in-depth study of

WSN applications to monitor and control the swiftlet

habitat. Tolle et al. presents a query-based frame-

work for temporal and spatial monitoring of a red-

wood tree for environmental monitoring (Tolle et al.,

2005). Arora et al. builds a real-time surveillance

system for target detection, classiﬁcation and tracking

using a central monitoring unit (Arora et al., 2004).

Sometimes, however, the only real time monitor-

ing is not sufﬁcient but it can be useful also to store

the data for further analysis and processing at a later

time. This implies that the sensors must be pro-

grammed to save the data locally and to send them

successively to a coordinator node (hereafter called

sink) to avoid congesting the communication chan-

nel with a huge amount of transmissions. Especially

when the number of sensors is high.

We also want to be able to control the entire sensor

network remotely without having to retrieve the sen-

sors once they have been installed. In certain cases,

for example in wildlife monitoring applications, once

the sensor has been installed on the body of the an-

imal is no longer possible to recover it if we do not

want to disturb the observation.

The objective of this work is to provide a frame-

work for remotely control a set of Motes for both real-

time and off-line data acquisition. The tool is com-

patible with the IRIS, MicaZ and TelosB platforms.

With this tool, the user can request a series of mea-

surements related to surrounding environment (light,

temperature, accelerometer, humidity, Pir - Passive

infrared, Magnetic, RSSI- Radio Signal Strength In-

dicator, and microphone). The data collected by the

Motes can be subsequently be forwarded to the sink,

which can store them in a local database, enabling the

user for off-line analysis and processing.

2 SYSTEM REQUIREMENTS

The system we have developed meets the following

basic requirements:

• Topology. Figure 1 shows the network architec-

ture of our WSN. The Motes acquire the requested

data and send them to the sink Mote either in a

real-time fashion, or on-demand when requested.

Amato G., Chessa S., Gennaro C., Pallini D. and Vairo C..

A Data Logger for Wireless Sensor Network.

DOI: 10.5220/0004315000650069

In Proceedings of the 2nd International Conference on Sensor Networks (SENSORNETS-2013), pages 65-69

ISBN: 978-989-8565-45-7

 2013 SCITEPRESS (Science and Technology Publications, Lda.)

Figure 1: The topology of the data logger.

The sink interfaces the WSN with the user: it

routes the data received from the other Motes to

the base-station (the PC) where they are stored

in a local database and visualized to the user by

means of the GUI.

• Mote Management and Setting. The number of

Motes involved in the query can change over time,

and each of them can be managed independently

from the others. Each Mote must be able to be set

up, turned on and off without affecting the oper-

ation of the other Motes in the network. At the

same time, the system must allow the user to acti-

vate, deactivate or reset all Motes on the network

simultaneously. The main parameters that can be

set in mote are the following:

– Sampling period. It indicates the period of time

(expressed in milliseconds) between two con-

secutive readings of the transducers.

– Type of transducer. It allows the user to choose

which transducers of the sensor board the Mote

has to sample.

• On-line and Off-Line Data Collection. The

monitor application on the Motes can be exe-

cuted in two modalities: on-line and off-line. The

on-line mode provides the data collected in real-

time for being immediately stored in the cen-

tral database when they are received by the base-

station. In the off-line mode, on the other hand,

the data are temporarily stored within the Mote

ﬂash memory and they can be downloaded at a

later time, upon a speciﬁc request from the user.

• Data Storage. - Each data detected by transduc-

ers mounted on Motes must be stored in a central

database located on the base-station, allowing the

user to access the data and analyze them anytime.

Note that in most WSN application scenario, the

amount of acquired data can be very large, so this

feature is particularly useful.

• Graphical User Interface. The Graphical User

Interface (GUI) allows the user to remotely setup

all the needed parameters on the Motes and to

activate/deactivate all the functionalities provided

by the logger. Moreover, the GUI visualizes the

receiveddata while they are stored in the database,

so a ﬁrst quick analysis of the data can be executed

without having to access the database. This is use-

ful in particular for the real-time applications.

3 ARCHITECTURE

The Data Logger consists of four separate software

components (see Figure 1):

• SincC is the gateway between the WSN and the

user that runs on Sink Mote.

• LoggerC is the component designated to collect

and store the data that runs on Motes.

• GUI is the user interface that runs on the base-

station.

• DB is the database for the storage of the data col-

lected that runs on the base-station.

3.1 SincC

The sink Mote is the access point to the network

from the real world. This Mote, therefore, forwards

the commands received from the base-station to the

other Motes of the network through the wireless com-

munication channel. It also routes all the data ac-

quired from the Mores in the network towards the

base-station to which it is connected through a serial

channel. The nesC component, that implements such

functionality similar to a hub, is called SincC and it

has to be installed on the sink Mote.

3.2 LoggerC

The rest of the Motes in the network have the same

nesC application installed on board called LoggerC.

Their typical function is to read the values from the

transducers integrated on the sensorboard, store the

acquired data in their internal ﬂash memory and/or

send them to the sink.

SENSORNETS2013-2ndInternationalConferenceonSensorNetworks

Figure 2: The Entity-Relationship diagram of the database.

3.3 GUI

Through the GUI the user is able to remotely instruct

the LoggerC components to start/stop the sampling,

to download the data stored in the ﬂash memory of

a Mote and to erase the memory after the download

has been completed. The GUI also allows the user

to specify the parameters needed for the monitoring

task: sampling period at which the data have to be

acquired, transducers to sample, acquisition modality

(on-line and/or off-line), the ID of the target Mote or,

in case of storing in the ﬂash memory and erasing the

ﬂash memory content, to send the command in broad-

cast to all the Motes. The Sink connected to the base-

station redirects the command speciﬁed in the GUI to

the target Mote. In case of on-line mode, the acquired

data are immediately sent back to the base-station and

they are displayed on the GUI and stored in the DB. In

case of off-line mode, instead, the data are only stored

in the ﬂash memory of the Mote. In order to get these

data, a speciﬁc download command has to be sent and

the data are received, stored in the DB and visualized

in the GUI, as in the on-line scenario.

3.4 DB

The DB component is an SQL relational database.

The tables created in the database regard the exper-

iments performed (Experiments entity), and the data

recorded by the sensors (DataSample entity). Figure

2 shows the entity-relationship schema of the Data

Logger database. Each experiment is associated with

an ID, called ExpID. Therefore we have a tuple for

each experiment in the Experiments table and the as-

sociation that links the two tables is provided by Ex-

pID, which is a foreign key in the DataSample table.

Here is the list of attributes of tables with related

information. Experiments table:

• ExpID. Unique identiﬁer of the experiment (pri-

mary key).

• Date. Starting date of the experiment.

• Time. Starting time of the experiment.

• SamplePeriod. Sample Period of the experiment.

• SensorMask. A bit-mask used representing which

transducers were active during the experiment.

• Flag. Indicates the choice of making an on-

line/off-line communication.

• Notes. Contains any notes entered by the user

when creating the experiment.

SampleDate table:

• SampleID. Unique identiﬁer of the sample data

(primary key).

• ExpID. Unique identiﬁer of the experiment for

which the sample belongs to (foreign key).

• SensorID. Unique identiﬁer of the Mote in the net-

work.

• AccX. Sampled value from the x-axis accelerom-

eter.

• AccY. Sampled value from the y-axis accelerome-

ter.

• Temperature. Sampled value from the thermome-

ter transducer.

• Light. Sampled value from the light transducer.

• Humidity. Sampled value from the humidity

transducer.

• Pir. Sampled value from the Pir transducer.

• Magnetic. Sampled value from the Magnetic

transducer.

• RSSI. RSSI value of the communication between

the sink and the target Mote.

• Mic. Sampled value from the microphone.

4 IMPLEMENTATION AND

USAGE

4.1 Setting Up an Experiment

Here we describe the use of the GUI of the data logger

shown in Figure 3.

• New Experiment button. This button is used to

create a new entry in the experiments table in the

DB.

• Sampling Period text box. It allows the user to

setup up the sampling period of the transducers

readings (expressed in msec).

ADataLoggerforWirelessSensorNetwork

• Transducers radio buttons. Eight radio buttons

that allow the user to select which transducers ac-

tivate on the Motes during the experiment.

• Online Data check button. If selected, the data

are sent to the sink in real-time when they are ac-

quired by the target Mote.

• Store Info. If selected, the acquired data are

stored in the ﬂash memory of the target Mote

(these two last options can be jointly checked).

• Target Mote text box. Speciﬁes the ID of the

Mote from which to acquire data. Note that, in or-

der to avoid collisions, only one mote is allowed

if the Online Data modality is set, that is the real-

time data can be received from one mote at a time.

• Broadcast checkbox. This option is available

only for the Store Info mode and to erase the ﬂash

memory of the motes. By checking it, the storing

of data in the ﬂash memory, or its deletion, can be

requested contemporarily on all the motes.

• Note textbox. It allows the user to associate the

experiment entry with a textual comment.

• Command buttons Start, Stop, Download, and

Reset Flash. Once a new experiment entry has

been created, the sampling task is activated by

clicking on the Start button. As consequence, the

Mote speciﬁed in the Target Mote text-ﬁeld will

start sending its acquired data and they will be

visualized in the GUI. If the Store Info modality

was set, the blue LED toggling on the Motes noti-

ﬁes the writing of the acquired data into the ﬂash

memory. The Stop button terminates the sampling

task. This command can also be sent in broadcast

by checking the Broadcast checkbox. To down-

load the data stored in a Mote into the database,

the button Download is used. In order to avoid

collisions, this operation is allowed for only one

Mote at a time. The green LED toggling on the

target Mote notiﬁes the reading from the ﬂash.

The receiveddata are stored in the DataSample ta-

ble of the database in the same order as they have

been acquired in the Mote and they are stored with

the reference to the experiment in the table Ex-

periments that contains the timestamps at which

the sampling started and the sampling frequency.

The Reset button erases the ﬂash memory of the

Mote. This operation may take a long time and its

progress is signaled by the red LED on the Mote:

it is on during the execution of the operation and it

is turned off when it is completed. This command

can also be sent in broadcast. It is important to ex-

ecute this command in order to have always clean

data.

Figure 3: The GUI of the data logger.

5 CONCLUSIONS

In this article we have presented a data logger for

WSN that allows both real-time data acquisition

and storing on the acquired data in the ﬂash mem-

ory of the Motes for off-line analysis. The soft-

ware is freely downloadable at www.nmis.isti.cnr.it/

gennaro/logger.zip and runs on Linux where Postgres

DBMS (www.postgresql.org) is installed. As future

developments, we aim at providing the possibility to

execute the on-line data acquisition on all the sensors

at the same time, by implementing a mechanism for

avoiding the collision of the packets.

REFERENCES

Arora, A., Dutta, P., Bapat, S., Kulathumani, V., Zhang,

H., Naik, V., Mittal, V., Cao, H., Gouda, M., Choi, Y.,

Herman, T., Kulkarni, S., Arumugam, U., Nesterenko,

M., Vora, A., and Miyashita, M. (2004). A line in the

sand: A wireless sensor network for target detection,

classiﬁcation, and tracking. Computer Networks (El-

sevier, 46:605–634.

Baronti, P., Pillai, P., Chook, V. W., Chessa, S., Gotta, A.,

and Hu, Y. F. (2007). Wireless sensor networks: A sur-

vey on the state of the art and the 802.15.4 and zigbee

standards. Computer Communications, 30(7):1655 –

1695. ¡ce:title¿Wired/Wireless Internet Communica-

tions¡/ce:title¿.

Culler, D., Estrin, D., and Srivastava, M. (2004). Guest

editors’ introduction: Overview of sensor networks.

Computer, 37:41–49.

SENSORNETS2013-2ndInternationalConferenceonSensorNetworks

Romer, K. and Mattern, F. (2004). The design space of

wireless sensor networks. Wireless Communications,

IEEE, 11(6):54 – 61.

Tolle, G., Polastre, J., Szewczyk, R., Culler, D., Turner, N.,

Tu, K., Burgess, S., Dawson, T., Buonadonna, P., Gay,

D., and Hong, W. (2005). A macroscope in the red-

woods. In Proceedings of the 3rd international confer-

ence on Embedded networked sensor systems, SenSys

’05, pages 51–63, New York, NY, USA. ACM.

Yamamoto, H., Uchiyama, S., Yamamoto, M., Nakamura,

K., and Yamazaki, K. (2012). Development of sensor

network for ecology observation of seabirds. IEICE

Transactions, 95-D(2):532–539.

ADataLoggerforWirelessSensorNetwork