Design of a Hybrid (Wired/Wireless) Acquisition Data System for Monitoring of Cultural Heritage Physical Parameters in Smart Cities

Senso s 2015, 15, 7246-7266; doi:10.3390/s150407246 senso s ISSN 1424-8220 www.mdpi.com/jou nal/senso s A icle Design o a Hyb id (Wi ed/Wi eless) Acquisi ion Da a Sys em o Moni o ing o Cul u al He i age Physical Pa ame e s in Sma Ci ies Fe nando-Juan Ga cía Diego 1,2,*, Bo ja Es eban 1 and Paloma Me ello 1,3 1 Depa men o Applied Physics, Uni e si a Poli ècnica de València, A . de los Na anjos s/n, Valencia 46022, Spain; E-Mails: [email p o ec ed] (B.E.); [email p o ec ed] (P.M.) 2 Cen o de Tecnologías Físicas, Uni e si a Poli ècnica de València, A . de los Na anjos s/n, Valencia 46022, Spain 3 Ins i u o Valenciano de Conse ación y Res au ación de Bienes Cul u ales (IVC+R), Complejo Socio-Educa i o de Penye a Roja s/n, Cas ellón 12080, Spain * Au ho o whom co espondence should be add essed; E-Mail: [email p o ec ed]; Tel.: +34-96-3877000 (ex . 75241). Academic Edi o : An onio Pulia i o Recei ed: 8 Janua y 2015 / Accep ed: 16 Ma ch 2015 / Published: 25 Ma ch 2015 Abs ac : P e en i e conse a ion ep esen s a wo king me hod and combina ion o echniques which helps in de e mining and con olling he de e io a ion p ocess o cul u al he i age in o de o ake he necessa y ac ions be o e i occu s. I is acknowledged as impo an , bo h in e ms o p ese ing and also educing he cos o u u e conse a ion measu es. The e o e, long- e m moni o ing o physical pa ame e s in luencing cul u al he i age is necessa y. In he con ex o Sma Ci ies, moni o ing o cul u al he i age is o in e es in o de o pe o m u u e compa a i e s udies and load in o ma ion in o he cloud ha will be use ul o he conse a ion o o he he i age si es. In his pape he de elopmen o an economical and app op ia e acquisi ion da a sys em combining wi ed and wi eless communica ion, as well as hi d pa y ha dwa e o inc eased e sa ili y, is p esen ed. The de ice allows moni o ing a complex ne wo k o poin s wi h high sampling equency, wi h wi ed senso s in a 1-wi e bus and a wi eless cen alized sys em eco ding da a o moni o ing o physical pa ame e s, as well as he u u e possibili y o a aching an ala m sys em o sending da a o e he In e ne . This has been possible wi h he de elopmen OPEN ACCESS Senso s 2015, 15 7247 o h ee boa d’s designs and mo e han 5000 algo i hm lines. Sys em es s ha e shown an adequa e sys em ope a ion. Keywo ds: cul u al he i age; mic oclima ic moni o ing; acquisi ion da a sys em; wi ed/wi eless; Sma Ci ies 1. In oduc ion P e en i e conse a ion me hods a e based on he concep ha con olling some o he majo de e io a ion causes in he en i onmen i is possible o ensu e he sus ainabili y and du abili y o he a wo k [1]. Depending on he na u e o cul u al he i age, he de e io a ion causes a e subjec ed o he in luence o di e en physical pa ame e s. Fo example, a wo ks a e in luenced by e ms o s ess caused by physical agen s such as empe a u e, humidi y, adia ion, and chemical agen s (e.g., CO2, SO2, O3, mine al sal s, e c.) [2], meanwhile, empe a u e and humidi y can each especial impo ance on a chaeological s uc u es because o being majo ly s one-buil [3,4]. Bu gene ally, ab up changes o empe a u e and ela i e humidi y (RH) may cause se ious damage in all he di e en kind o objec s, such as non-iso opic ma e ial de o ma ion o de achmen in ma e ials o se e al laye s [5]. In hyg oscopic ma e ials, such as wood panels, which a e he mains ay o many a wo ks, mechanical changes and de o ma ions could occu [6]. In he case o escoes, soluble sal s and mois u e a e he e y common causes o de e io a ion; he e o e an ea ly de ec ion o dange ous alues o hese physical pa ame e s ( oge he wi h o he chemical pa ame e s in some cases) is essen ial o a oid his kind o damage [7]. Thus, bo h long- e m moni o ing o he en i onmen al pa ame e s as well as u he analysis o he eco ded da a a e necessa y [8]. The concep o “Sma Ci y” is no o iously liquid, sca cely o malized and, in some deg ee, subjec o di e en ideological in e p e a ions [9]. No mally Sma Ci y is associa ed wi h eal- ime moni o ing and cloud compu ing [10]. Howe e , Sma Ci ies should no necessa ily be es ic ed o eal- ime moni o ing. In ac , in he case o moni o ing cul u al he i age, his o ical da a (wi hou unde es ima ing eal- ime ala ms, e c.) is mo e in e es ing as i is impo an o cha ac e ise he si e o pe o ming compa a i e s udies in he u u e, ei he egula ly, in o de o e i y whe he he condi ions a e cons an , o occasionally, when he bounda y condi ions a e al e ed [11]. Thus, he aim o moni o ing cul u al he i age in a Sma Ci y would be sending all hese eco ded da a o in e ne so hey can be checked and se e as an example o he conse a ion o o he simila si es. The en i onmen al moni o ing is pe o med by a egula da a eco ding, whose equencies ypically ange be ween one da um e e y hou (1 da um/h) o e e y day (1 da um/day) [12,13]. Moni o ing wi h equencies nea 60 da a pe hou (1 da um/min) is in e es ing as powe and con idence o he s a is ical analysis pe o med inc eases in di ec p opo ion o he sample size used [8], and he e o e de elop a moni o ing sys em wi h la ge g id o senso s and big memo y o s o e la ge amoun s o da a om high eco ding equencies is in e es ing. Di e en wo ks moni o ing cul u al he i age a e ound in he li e a u e [14,15]. Mos o hem use indi idual da a-logge s. Some au ho s [16] use Hobo da a-logge s [17], and o he s udies [6,11,18] wo k Senso s 2015, 15 7248 wi h da a-logge s DS1922L [19] and DS1923 [20]. Da a om hese da a-logge s canno be sen au oma ically o he cloud and due o hey a e comme cial de ices, i s ha dwa e and so wa e is unknown and canno be modi ied. The e a e also pape s ha ha e s udied he mic oclima e in chu ches making use o a wi ed senso ne wo k composed o di e en lines and senso s and a single mic ocon olle [7,21]. The expe ience wi h he DS1923 [18] has demons a ed ha indi idual da a-logge s ba e y and memo y ge deple ed a ound he hi d mon h o wo k in cases whe e da a has o be aken wi h high equency. Mo eo e , esul s o each da a-logge mus be combined in o one ile. So wa e o combine he da a au oma ically once hey a e in he compu e could be de eloped; howe e he ha des pa o he wo k consis s in loading da a in o he compu e one by one. A senso ne wo k sol es he issue o he lack o memo y and ba e y bu only SDI-12 [22] p o ocol is able o each cable leng h o 250 m and de ices wi h his p o ocol a e much mo e expensi e and do no allow connec ing enough senso s (no mo e han 60) o co e cul u al he i age applica ions [21]. The e o e, he bes op ion is o de elop a new kind o ne wo k da a-logge adding mo e cable leng h, amoun o senso s connec ion, lexibili y and lowe consump ion and p ice han a compu e and o he da a acquisi ion sys ems. The own de elopmen o moni o ing sys ems om he expe ience o he equi emen s o he pa icula ield o ac ion is essen ial o he echnical and cos e iciency o hese [23]. Some pape s ha e de eloped acquisi ion sys ems o emo e con ol applied o cul u al he i age [24,25]. This pape deals wi h he necessi y o a low cos da a-logge able o collec and eco d da a o physical pa ame e s om ex ended a eas o p e en i e conse a ion applica ions, combining wi ed and wi eless communica ion p o ocols. In his pape we p esen a de ice able o communica e wi h senso s using 1-Wi e p o ocol, p og ammed o con ol he equency o da a cap u e, wi h a ailu e p o ec ion sys em, mee ing as much as possible wi h he equi emen s o he ma ke and consume s and wi h a e sa ile p og amming ha allows i s ex ension o di e en applica ion such as ala ms, sending da a ia In e ne , e c. o Sma Ci ies. 2. Ma e ials and Me hods 2.1. Senso s The de ice will be de eloped hinking on he senso s selec ed and hei p o ocol o communica ion. In his case, senso s a e p ede e mined by Maxim In eg a ed Company o i s p o en ope abili y in cul u al he i age pu poses [7,21], as well as i s wide ange o e o senso s, analogue o digi al con e e s and no expensi e p ices. A p ac ical applica ion o he es ing o he sys em is pe o med a he end o his pape . Two 1-Wi e sla es we e assembled in a single double sided p in ed boa d o 12 mm × 26 mm: a DS18B20 [26], which is a empe a u e senso wi h an accu acy o ±0.5 °C, wi h a ange o measu emen s om −10 o +85 °C, and an Analog o Digi al Con e e (ADC) DS2450 (Maxim In eg a ed P oduc s, Inc., San Jose, CA, USA) [27] which can use one o i s ou channels o ead he analog po en ial o a HIH 4030-001 RH senso [28] (Honeywell In e na ional, Inc., Minneapolis, MN, USA) wi h ±3.5% RH accu acy (uncalib a ed) and a ange o measu emen s om 0% o 100% o ela i e humidi y. Senso s 2015, 15 7249 The Maxim In eg a ed de ices ha e hei own and unique se ial numbe implemen ed in p oduc ion and impossible o change. A calib a ion p ocedu e wi h aqueous solu ions o wo sal s (li hium chlo ide and sodium chlo ide) was applied in labo a o y acco ding o he s anda d ASTM E 104–02 [29] in o de o s udy he measu emen e o s o RH senso s. All RH senso s we e in oduced in a small chambe equilib a ed wi h a sa u a ed solu ion o a sal . Nex , calib a ion equa ions we e ob ained o each senso in o de o ela e he ol age ou pu and RH. 2.2. Wi ed T ansmission P o ocols The p o ocol selec ed o con olling he senso s by he mas e is 1-Wi e. The numbe o senso s and he es ic ions o ins all hem in each applica ion a e qui e unp edic able. So o o e a majo lexibili y in o he da a logging ne wo k, he s uc u e o he da a-logge is going o be di ided in o h ee di e en modules (Mas e module, Sla e module, and Wi eless module). In o de o make a ailable he communica ion, each module has o ha e i s own mic ocon olle , so one is ins alled in each module, and I2C p o ocol is selec ed o communica e modules physically connec ed. This p o ocol will be used o he da a ansmission h ough he boa d as i o e s a good baud a e wi h synch onic communica ion and i is e y simple o implemen . 2.3. Wi eless T ansmission P o ocol The sys em includes an xBee module o o e wi eless suppo [30]. This de ice is able o ou e messages using he IEEE 802.15.4 s anda ds. This p o ocol o e s o hese modules he nex ea u es: low ax o noise in e e ence, low ax o in e e ences, low powe consump ion (depends on he ac ua ion ange), high axes o ansmission powe and ecep ion sensibili y, ex a enc yp ion se ices (applica ion and ne wo k keys implemen ex a 128b AES enc yp ion), associa ion and au hen ica ion (only alid nodes can join o he ne wo k), AODV ou ing p o ocol [30]. This allows he da a-logge o send in o ma ion abou i s senso s o a Mas e de ice in o de o s o e da a. Fu he mo e, he sys em can include as many wi eless da a-logge s as is necessa y o accomplish he numbe o senso s and dis ance equi emen s. 2.4. Mic ocon olle ATmega328 In o de o dispose a simple p og amming en i onmen all he lib a ies we e implemen ed in C++ o he mic ocon olle . The company A duino o e s a solu ion wi h all he mic ocon olle unc ions needed o he applica ion. Speci ically mic ocon olle ATmega328 is a ailable in he ma ke wi h a low p ice and has “A duino UNO” boa d o p og am he mic ocon olle . The ATmega328 has he minimal equi emen s o he applica ion. I has one I2C po in o de o connec wi h he de ice DS2482-800 [31] and he ex e nal clock [32] oge he wi h an USART o connec o he pe iphe als like an USB memo y. The p og ammable memo y is 32 kB so i is enough o s o e all he necessa y lib a ies, he se ial numbe o he senso s and he main p og am. Mo eo e , i is equipped wi h digi al and analogic inpu s and ou pu s modula ed by PWM o imp o e o adap ou da a-logge o a wide ange o possibili ies. Senso s 2015, 15 7250 Communica ion be ween mic ocon olle s is possible using he I2C po be ween modules and he USART po o he wi eless de ice. A duino In eg a ed De elopmen En i onmen (IDE) p o ides all he lib a ies o enable his communica ion. As he mic ocon olle does no ha e 1-Wi e po , de ice DS2482-800 o Maxim In eg a ed [31] manages au oma ically 1-Wi e p o ocol enabling he sys em o connec a heo e ically unlimi ed numbe o senso s pe channel and a kilome e o wi e. This de ice is equipped wi h 8 di e en 1-Wi e channels. 2.5. Ex e nal Clock The DS1307 (Maxim In eg a ed, Inc., San Jose, CA, USA) is he de ice implemen ed as ex e nal clock on he p in ed ci cui boa d. This de ice also uses I2C p o ocol o communica e wi h he mic ocon olle , has a low consump ion ene gy a e and an ex e nal ba e y o gua an eeing he ope a ion i he main inpu cu en alls down [32]. 2.6. Ex e nal USB Memo y Da a-logge is de eloped o sa e all da a inside an ex e nal memo y by he use o a pe iphe al USB. The de ice used o a ange he USB is he pe iphe al VDIP1. This de ice and i s mic ocon olle FTDI ha e been de eloped by he company Fdichip [33] and include all he necessa y p og ams ins alled o p o ide access by he UART, pa allel FIFO o SPI in e ace pins on he main mic ocon olle . The communica ion selec ion is p o ided by wo jumpe pin heade s o allow by simple con igu a ion o he I/O on da a and con ol bus pins o he VDIP1. In his case, he communica ion is managed by he UART po connec ed o he USART po o he main mic ocon olle . 2.7. DC Powe Supply De ices NCP7805TG [34] and UA78M33CKCS [35] ha e been ins alled on he boa d in o de o o e a s able ou pu cu en wi h a high a e o inpu ol age. 2.8. The Failu e Managemen Failu e managemen sys em includes he aspec s and de ices ha p o ec he da a acquisi ion agains unexpec ed e en s. To p o ec he sys em, he da a-logge will include a de ice named “Wa ch-Dog”, speci ically he TPS3813 by Texas Ins umen s [36]. This chip is used o ese he comple e sys em (wi hou dele ing any da a) in o de o es a he con igu a ion in o a known wo king poin . This es is pe o med in ime in e als ha will be se by he de elope acco ding o he sampling equency and he numbe o senso s. Fu he mo e, Time Ou s in all he loops o esume he p og am in case o ails in he communica ion p o ocols and da a acquisi ion will be included in he p og am. The las o hese Time Ou s can be modi ied in he main p og am by so wa e in o de o imp o e he communica ion depending on he amoun o sla es in he sys em. Senso s 2015, 15 7251 2.9. Desc ip ion o he Tes ing Expe imen An expe imen o moni o ing was pe o med in o de o check he sys em ope a ion, wi hou he goal o diagnosing i he en i onmen su ounding he selec ed a wo k is sui able o i s conse a ion. Resul s ob ained wi h he de eloped sys em a e compa ed wi h hose o a comme cial da a-logge ha has been used be o e in moni o ing o cul u al he i age. Each p obe o hese au onomous de ices consis s o one empe a u e da a-logge (model The moch on DS1922L [19]) and one RH da a-logge (model Hyg och on DS1923 [20]). Each da a-logge (DS1923) con ains a humidi y senso wi h an accu acy o ±5% and a empe a u e senso wi h an accu acy o ±0.5 °C. RH da a-logge s we e calib a ed wi h aqueous sal solu ions (as done wi h senso s in Sec ion 2.1) acco ding o he s anda d ASTM E 104–02 [29]. In 1928, he ex ile indus ialis Edua do Rome o Sanchis placed a acsimile, wi h de ail and iden ical o he Real Senye a on o de o he Ci y Council o Valencia, wea ed in silk: ou s ips o magen a silk on golden silk issue backg ound, wi h a blue s ipe on he lagpole side, wi h a golden c own, also in golden issue [37]. When he wo ldwide ecognized Valencian w i e Vicen e Blasco Ibañez died in 1928, he lag was mo ed o F ance o co e he co in. Some yea s a e , in 1932, i was mo ed o he same pu pose du ing his une al in Valencia a e he ans e o his emains. In Decembe 2009, he poli ical pa y Union Valenciana dona ed he lag o he Valencian Go e nmen unde he condi ion o i s es o a ion and conse a ion. Cu en ly i is displayed, a e i s es o a ion in 2013, in he Blasco Ibáñez Museum-House (Valencia, Spain), inside a sealed sligh ly inclined display cabine (317 × 223 × 12 cm) designed o his pu pose (Figu e 1). Figu e 1. Res o ed lag in he display cabine , Blasco Ibáñez Museum-House (Valencia). A pai o se s o wo DS2450 and HIH-4030 senso p obes we e ins alled (a couple inside he display cabine and he o he a he ou side), and p obe se wi h one comme cial DS1923 da a-logge was ins alled nex o he senso a he ou doo s o he display cabine as a es ing da a-logge . Fo he expe imen , senso s we e ins alled indoo s and ou doo s he display cabine . Ou de eloped moni o ing sys em is composed o h ee di e en modules (Mas e module, Sla e module, and Wi eless module ha will be desc ibed in Sec ion 3). In he ou doo s o he display cabine , he Mas e and a Sla e managing a line o wo senso s (one inside and he o he ou side he display cabine ) we e placed. The Senso s 2015, 15 7252 moni o ing expe imen s a ed on 17 No embe 2014 and ended on 27 No embe 2014. Du ing his pe iod o 11 days, each comme cial da a-logge eco ded one measu emen e e y 10 min (6 da a pe hou ) and each da a-logge o he designed sys em eco ded one measu emen e e y minu e (60 da a pe hou ). 3. Design o Ha dwa e and So wa e o he Da a Moni o ing Sys em The s uc u e o he da a-logge is going o be di ided in o h ee di e en modules (Mas e module, Sla e module, and Wi eless module). The goal o he Mas e module is o collec da a om all he sla e modules ins alled in he wi eless ne wo k and manage hem in o de o sa e he in o ma ion inside a USB memo y (in his p ojec ) o sending he in o ma ion o o he de ice such as a compu e . The Sla e module is he esponsible o collec ing da a om he senso s and sending he in o ma ion o he connec ed module. The Wi eless module is able o send he in o ma ion ecei ed om he connec ed module o o he Wi eless module o he opposi e. I is designed o connec wo modules and o m h ee di e en kinds o da a-logge s. Fo example i we connec a Mas e module wi h a Sla e module we will ha e a common da a-logge , bu we can c ea e a wi eless ne wo k sys em using wo Sla e modules and a Mas e module connec ing each one wi h a Wi eless module. Tha way, wo di e en da a-logge s can collec da a om wo di e en places and sa e hem in o he same ex e nal memo y by wi eless, allowing one, o example, o easily moni o di e en ooms in a museum wi h a unique moni o ing sys em. 3.1. Design o Ha dwa e o he Da a Moni o ing Sys em The i s subjec is he p in ed ci cui boa d (PCB) design because is he basis o he p oduc ion. Fo he de elopmen o his Sec ion he main p og am used o he designs is “Eagle CAD” [38]. When we s a ed he e is no supposed o be a limi o size bu i is ecommendable o minimise i in o de o o e a good design. Fu he mo e, he ee e sion o “Eagle CAD” only allows a ce ain maximum size o (56 × 36 × 23 cm). Du ing he design, a p o o ype had been c ea ed in o de o sol e possible oubles du ing he cons uc ion and he wo king li e. The inal solu ion is p esen ed in his Sec ion. 3.1.1. Design o he Powe T ack Two di e en supplying sys ems a e included. One +5 V DC cu en o he alimen a ion o he ATMega328 and o he s. This alimen a ion will be ins alled on he Mas e and Sla e modules. One +3.3 V DC cu en o he alimen a ion o he xBee in eg a ed (Wi eless module). The selec ed de ices o supply he powe a e he NCP7805TG egula o o he +5 V and he UA78M33CKCS o +3.3 V, allowing he da a-logge being connec ed o a wide ange o DC ans o me s. Besides he powe il e has been imp o ed om he A duino design, adding a small ce amic capaci o , using pa allel connexion, o he elec oly ic il e . Thus, inal combined il e has be e p op ie ies in e ms o esis ance and p ice. No e ha , i he loca ion has a high a e o illumina ion, i could be conside ed he op ion o looking o a posi ion wi h enough luminal in ensi y in o de o include a pho o ol aic sou ce o echa ge a Senso s 2015, 15 7253 da a-logge ba e y. Once he supply sys em has been designed, he nex s ep is o de ine he posi ion o each componen and connec he acks wi h he ex e nal connec ions. This s ep will be di e en in all he modules. The PINs used o connec di e en boa ds ha e o co e bo h sides in o de o be able o ha e a module up and also down. The connec ion dis ibu ion is simila o he A duino modules, ha way i is possible o c ea e new applica ions jus adding new so wa e and he co esponding boa d. A ese swi ch is also a ailable in he Mas e and Sla e modules; mo eo e his signal a ec s he connec ed Wi eless module oo. 3.1.2. Final Boa ds and Schema ics The majo i y o he powe acks such as GND, +3.3 V and +5 V a e designed wi h 0.8128 mm o wid h. The es o acks, as a as is possible, a e abou 0.5 mm. In he inal design, depending on he module, he connec ed de ices a e di e en . In he Mas e , he VDIP1 is connec ed wi h he ATMega328 using UART po (Figu e 2). Besides, o ensu e a co ec communica ion be ween hem, wo o he ATMega328 PINs a e used as “Clea o Send” (CTS) and “Reques o Send” (RTS) (Figu e 2). Those acks manage when bo h a e eady o enable a da a ansmission. Figu e 2. Mas e schema ic inal design. Senso s 2015, 15 7254 On he o he hand, he DS1307 (Ex e nal Clock) has been connec ed o he PINs ADC5 and ADC4 o he ATMEGA328 using “Se ial Da a Line” (SDA) and “Se ial Clock Line” (SCL) in o de o enable he I 2 C communica ion be ween hem. Rega ding he Wa ch-Dog, he “Wa chdog ime inpu ” (WDI) has been connec ed o one o he PINs o he ATMega328 o enable he Failu e Managemen . Finally, an op ional po has been ins alled o manage a “liquid c ys al display” (LCD), which could be ins alled in he p o o ype o ensu e co ec da a acquisi ion. Secondly, on he Sla e module, he USB pe iphe al and he ex e nal clock ha e been eplaced by he I 2 C o 1-Wi e ansla o (Figu es 2 and 3). The ex e nal 1-Wi e plug is he s anda d D-sub connec o MHDD which o e s 9 connexions: 1 o he G ound (GND), 1 o he Senso s Vol age supply (VDD) and 7 channels. The channel numbe 3 ou pu is ese ed and loca ed inside he boa d in o de o o e possible connexions inside he encapsula ion like o he kind o senso s o p o ec ions. Figu e 3. Sla e Schema ic Final Design. The Wi eless module has an XBee mic ocon olle (Figu e 4) o enable he wi eless communica ion be ween wo di e en modules by wi eless (able o communica e among hem using he IEEE 802.15.4 p o ocol and communica e wi h he A Mega328 using he USART po ). I can be used o communica e also Mas e o Sla e modules o a comme cial A duino boa d by I 2 C making i e y e sa ile and use ul in a wide ange o applica ions. Senso s 2015, 15 7261 indica e i . When he ansmission has inished and he Mas e has all he da a, i sends an O_CCmd (Figu e 6) command o elease he Wi eless module so i se s PIN_R = 0 again. 3.5 Sla e Module o Wi eless Module Communica ion The Sla e module algo i hm is designed o collec da a om all senso s connec ed while he Mas e module does no eques communica ion. Tha way, he s a e o i s senso s is always upda ed. This me hod o keeping all da a upda ed is use ul o u u e applica ions as he Sla e module can con ol in eal- ime he s a e o he wi ed ne wo k o senso s. Thus, he sla e can s a a communica ion wi h he Mas e module h ough he Wi eless o ac i a e, o example, an ala m. When he Wi eless module o which i is connec ed indica es ha a da a ansmission has been eques ed PIN_R = 1, so an in e up inside he mic ocon olle occu s and he Wi eless module s a s he da a ansmission using he I2C p o ocol. The Sla e module asks o he eques ed channel sending an O_SRCh command (Figu e 9) o he Wi eless sla e module, hen, i loads in o i s I2C exi bu e he numbe o he channel eques ed by he Mas e Module and indica es ha he message is a ailable o be ead. The e o e, he Sla e module sends a RF om command o ead he message wi h he eques ed channel. Figu e 9. Flowcha o wi eless o de s om Sla e module. Senso s 2015, 15 7262 A e his, he Sla e module, using he O_SSD command (Figu e 9), sends he senso s s o ed da a and he Wi eless s o es his da a inside he indica ed DP. When he Sla e module has inished, i sends an O_STD command wi h he numbe o LDP in o de o indica e ha he Wi eless module can s a he ansmission wi h he emi e o he eques . I he ansmission be ween Wi eless modules has been accep ed PIN_R = 0, indica ing ha he ansmission has been pe o med co ec ly. The communica ions p o ocols be ween one Mas e and one Sla e a e shown in Figu e 10 in simpli ied as an example; no e ha a wi eless ne wo k could ha e mo e Sla e modules. Figu e 10. Global communica ion example. 3.5. Sys em Tes ing The de eloped so wa e has been moni o ing o a pe iod o 11 days, wi h a moni o ing equency o one da um pe minu e, ob aining a o al o 15,840 da apoin s pe senso (60 da a/h × 24 h/day × 11 days). Fu he mo e, comme cial da a-logge s eco ded da a e e y 10 min ( o he con ol o he de eloped sys em). The ajec o ies o he h ee senso s a e shown in Figu e 11. Figu e 11. T ajec o ies o senso inside he display cabine ( ed), senso a he ou side o he display cabine (blue) and con ol da a-logge a he ou side o he display cabine (g een). (a) Tempe a u e; (b) RH. The mean daily ajec o y o da a eco ded inside he display cabine and ou side o i , as well as da a eco ded by he comme cial da a-logge s ha e been plo ed o assess he esul s ob ained by ou moni o ing sys em (Figu e 12). Senso s 2015, 15 7263 Figu e 12. Mean daily ajec o ies o senso inside he display cabine ( ed), senso a he ou side o he display cabine (blue) and con ol da a-logge a he ou side o he display cabine (g een). (a) Tempe a u e; (b) RH. Each RH measu ed by ou sys em ou o he display cabine di e s 1.09% on a e age om he con ol da a-logge . Fo he empe a u e he di e ence is 0.46%. In absolu e e ms, his mean di e ence is 3.72% RH and 0.54 °C o empe a u e. These alues a e wi hin he e o ange o he senso s (±5% RH and ±0.5 °C). 4. Conclusions A de ice which accomplishes he main equi emen s o being used in moni o ing physical pa ame e s o cul u al he i age pu poses has been success ully de eloped. One Mas e , one Sla e and wo Wi eless p o o ypes modules ha e been designed o e i y he consis ence o he designs. The modules can be connec ed con enien ly o con igu e a moni o ing sys em ha sui s he cul u al he i age si e. In addi ion, hi d pa y ha dwa e is used in o de ha he sys em can be e y e sa ile because di e en modules a ailable on he ma ke can be a ached o sending an ala m by SMS, eco ding da a in he cloud, swi ch on/o an HVAC sys em, e c. As he sys em eads a ou channel ADC (DS2450), each in eg a ed ci cui can connec up o ou senso s ha ans o m he measu ed physical pa ame e in o a change in he elec ic po en ial. Lib a ies ha e been p og ammed o a ailu e p o ec ion sys em using a Wa ch-Dog and iden i ying co up ed by es inside da a ansmission. The eby, i is ensu ed ha s o ed da a is co ec and he sys em does no come in o in ini e loops o c ash. Fu he mo e, an in e nal clock ha con ols he equency o da a cap u e has been p og ammed. Mo eo e , due o he ime i akes o sa e e e y da a, he p o o ypes ha e been able o sa e he measu es om 80 senso s ex ac ed om he Sla e module inside a USB memo y in less han 30 s o ime and eco d measu es o empe a u e and humidi y om a su ace o 2000 m2. The sys em has a da a s o age capaci y which depends on he USB memo y used. Fo a 2 GB USB memo y and 20 senso s eco ding da a e e y minu e he sys em will be able o sa e da a con inuously du ing 10 yea s. E en low le el memo ies a ound 100 Mb ensu e he au onomy o he da a-logge o mo e han one yea . The whole sys em has been made using ee ha dwa e-so wa e o ial e sions so i s de elopmen has been possible hanks o he open scien i ic knowledge on he In e ne . A p ac ical es ing o he sys em has e ealed i s sui abili y and ma ching esul s wi h comme cial da a-logge s used in cul u al he i age. Senso s 2015, 15 7264 Acknowledgmen s The au ho s acknowledge he collabo a ion o Rosa Ma ía Rod íguez y Belén Villanue a, supe io and managemen echnicians o Blasco Ibáñez Museum-House espec i ely. This wo k was pa ially suppo ed by he Spanish Go e nmen (Minis e io de Economía y Compe i i idad) unde p ojec s HAR2013-47895-C2-1-P and HAR2013-47895-C2-2-P. Au ho Con ibu ions F.-J.G.D was esponsible o he de elopmen o he idea. P.M. pe o med he s a is ical analysis. B.E. conduc ed so wa e and ha dwa e de eloped. W i ing o he pape was sha ed be ween he h ee au ho s. Con lic s o In e es The au ho s decla e no con lic o in e es . Re e ences 1. Kolle , M. Lea ning om he His o y o P e en i e Conse a ion. In P e en i e Conse a ion: P ac ice, Theo y and Resea ch; Ashok, R., Smi h, P., Eds.; In e na ional Ins i u e o Conse a ion o His o ic and A is ic Wo ks: London, UK, 1994. 2. Na ional Galle y o Aus alia. P e en i e Conse a ion. 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This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion license (h p://c ea i ecommons.o g/licenses/by/4.0/).