Ci a ion: Tapia, E.; Sas oque-Pinilla, L.;
Lopez-No oa, U.; Bediaga, I.;
López de Lacalle, N. Assessing
Indus ial Communica ion P o ocols
o B idge he Gap be ween Machine
Tools and So wa e Moni o ing.
Senso s 2023,23, 5694. h ps://
doi.o g/10.3390/s23125694
Academic Edi o : Iwona G obelna
Recei ed: 19 May 2023
Re ised: 16 June 2023
Accep ed: 16 June 2023
Published: 18 June 2023
Copy igh : © 2023 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
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 (CC BY) license (h ps://
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4.0/).
senso s
A icle
Assessing Indus ial Communica ion P o ocols o B idge
he Gap be ween Machine Tools and So wa e Moni o ing
Endika Tapia 1,* , Leona do Sas oque-Pinilla 1, Unai Lopez-No oa 1,2 , Iñigo Bediaga 3
and No be o López de Lacalle 1,4
1Ae onau ics Ad anced Manu ac u ing Cen e , Uni e si y o he Basque Coun y, 48940 Leioa, Spain;
edwa leona do.sas [email protected] (L.S.-P.); [email protected] (U.L.-N.); no be [email protected] (N.L.d.L.)
2Depa men o Compu e Languages and Sys ems, Uni e si y o he Basque Coun y, 48940 Leioa, Spain
3Ideko, 20870 Elgoiba , Spain; [email p o ec ed]
4Depa men o Mechanical Enginee ing, Uni e si y o he Basque Coun y, 48940 Leioa, Spain
*Co espondence: [email p o ec ed]
Abs ac :
Indus ial communica ion p o ocols a e p o ocols used o in e connec sys ems, in e aces,
and machines in indus ial en i onmen s. Wi h he ad en o hype -connec ed ac o ies, he ole
o hese p o ocols is gaining ele ance, as hey enable he eal- ime acquisi ion o machine moni-
o ing da a, which can uel eal- ime da a analysis pla o ms ha conduc asks such as p edic i e
main enance. Howe e , he e ec i eness o hese p o ocols is la gely unknown and he e is a lack
o empi ical e alua ion which compa es hei pe o mance. In his wo k, we e alua e OPC-UA,
Modbus, and E he ne /IP wi h h ee machine ools o assess hei pe o mance and hei complex-
i y o use om a so wa e pe spec i e. Ou esul s show ha Modbus p o ides he bes la ency
igu es and communica ion has di e en complexi ies depending on he used p o ocol, om he
so wa e pe spec i e.
Keywo ds:
pe o mance e alua ion; moni o ing; indus ial communica ion p o ocols; da a acquisi ion;
machine ools
1. In oduc ion
The adop ion o eme ging echnologies such as he Indus ial In e ne o Things (IIoT),
Big Da a, and A i icial In elligence (AI) is expe iencing no able g ow h in o ganiza ions.
This end aims o enhance p oduc i i y and inc ease compe i i eness in he ma ke .
These echnologies enable he collec ion o la ge olumes o da a and he applica ion o ad-
anced analy ical algo i hms o ob ain aluable eal- ime insigh s. In highly in e connec ed
en i onmen s, e iciency and quali y hea ily ely on da a acquisi ion and he implemen a-
ion o p edic i e models, making hese echnologies essen ial componen s [1,2].
Figu e 1 ep esen s he di e en s ages in a pla o m o ien ed o da a analysis. The i s
s age, which is one o he main ocuses o his a icle, is cen e ed a ound acqui ing ele an
da a a he equi ed equencies, which en ails de e mining how o access hem. Once he
da a a e collec ed, hey need o be p ocessed and ans o med o subsequen analysis and
model aining. Nex , he e is he da a publica ion s age, which may in ol e using he
model o making p edic ions o isualiza ion pu poses. Finally, da a s o age ensu es hei
euse in he u u e.
Howe e , despi e i s emendous po en ial, he e a e s ill obs acles ha hinde i s
widesp ead adop ion in nume ous companies, as indica ed in he Eu opean Commission
epo on he Eu opean Da a S a egy [
3
]. One o he main easons o his si ua ion is
he complexi y associa ed wi h ex ac ing p oduc ion da a, especially in ad anced man-
u ac u ing en i onmen s whe e eal- ime analy ics a e sough . The complexi y o his
challenge s ems om he di e si y o sou ces and indus ial communica ion p o ocols
Senso s 2023,23, 5694. h ps://doi.o g/10.3390/s23125694 h ps://www.mdpi.com/jou nal/senso s
Senso s 2023,23, 5694 2 o 15
(ICPs) a ailable in each o hem, he lack o s anda diza ion, he lack o in e ope abili y
be ween sys ems and equipmen , as well as he a iabili y in da a o ma s and quali y.
Figu e 1. Rep esen a ion o he ypical s ages in a da a analysis pla o m.
Machine ools in ad anced manu ac u ing en i onmen s a e usually equipped wi h a
P og ammable Logic Con olle (PLC), an embedded compu e esponsible o managing
au oma ion logic and da a handling, among o he s. The demand o connec i i y o hese
PLCs has been inc easing o mee he cu en indus y equi emen s [
4
], h ough he use o
a ailable ICPs. These p o ocols enable connec i i y be ween machines, equipmen , and
sys ems as pa o an indus ial ne wo k, p o iding comp ehensi e isibili y and con ol
o e ac i i ies ca ied ou in he p oduc ion a ea. To le e age machine da a and ha ness
he po en ial o Indus y 4.0 applica ions, i is essen ial o acqui e da a wi h app op ia e
la ency based on he a ge s o he applica ion. Howe e , he challenges o e icien ly use
indus ial ne wo ks and p o ocols emain o be p ope ly laid ou .
Rela ed Wo k
When conduc ing bibliog aphic esea ch in he scien i ic li e a u e, i becomes e iden
ha he e is a sca ci y o esea ch conduc ing empi ical e alua ions o he pe o mance o
ICPs such as Open Pla o m Communica ions Uni ied A chi ec u e (OPC-UA) o E he -
ne /IP. Among he ew s udies ca ied ou is he wo k o Wang e al. [
5
], who compa ed he
pe o mance be ween OPC-UA and Messaging Queuing Teleme y T anspo (MQTT) in
e ms o packe o e head, la ency, packe loss and CPU usage, demons a ing ha MQTT
deli e s be e pe o mance in e ms o packe o e head and CPU u iliza ion. In a ela ed
s udy, Rocha e al. [
6
] pe o med a pe o mance compa ison be ween OPC-UA and MQTT,
ocusing on he o e all da a ans e quan i y, including use payload and o e head, as
well as he ound ip ime o da a exchange and eedback. Thei expe imen al analysis
encompassed di e se cloud compu ing se e and applica ion scena ios. The indings o
he s udy also e ealed ha MQTT exhibi ed as e pe o mance han OPC UA speci ically
o pu e da a exchange.
Fu he mo e, Ca ale i and Cu uli [
7
] conduc ed a s udy p oposing measu emen
pa ame e s o e alua ing he pe o mance o OPC UA. Thei esea ch emphasized he
impo ance o key ea u es such as secu i y, subsc ip ion mechanisms, and sampling
in e als. Im iaz and Jaspe nei e [
8
] in es iga ed OPC-UA as a middlewa e solu ion o
esou ce-limi ed de ices. They implemen ed an OPC-UA se e based on he “Nano
Embedded De ice Se e p o iles” o he OPC Founda ion, demons a ing ha OPC-UA
can scale down o a chip le el while e aining i s p ominen ea u es and use ulness.
On he o he hand, he e a e nume ous s udies ha compa e di e en cha ac e is ics o
ICPs bu do no conduc empi ical pe o mance e alua ions. Fo ins ance, Ani ha e al. [
9
]
analyzed and compa ed he implemen a ion o di e en p o ocols based on ne wo k opol-
ogy (HTTP, MQTT, CoAP, XMPP, AMQP, and Modbus), along wi h hei compu a ional and
Senso s 2023,23, 5694 3 o 15
la ency pe o mance. Pe ko and Naumo [
10
] desc ibed he indus ial communica ions
used in p ocess au oma ion, he challenges and p ac ical opologies o au oma ion ne -
wo ks, and echnological pe spec i es. Addi ionally, Vi u i e al. [
11
] p o ided a e iew o
indus ial communica ion ne wo ks, add essing he s a e o he a and ou lining in e es ing
u u e pe spec i es. Meanwhile, Lin and Pea son [
12
] examined a ious indus ial e he ne
p o ocols and ad oca e o he need o c ea e a uni ied ha dwa e and so wa e pla o m
upon which mul iple s anda ds can be implemen ed, o e ing eal- ime communica ion,
de e minism, and low la ency.
Ensu ing he secu i y o communica ion p o ocols is o pa amoun impo ance o
p o ec indus ial sys ems and sensi i e da a om unau ho ized access and malicious
a acks. Gu o e al. [
13
] emphasized he challenge o achie ing ubiqui ous connec i i y
o senso s in noisy indus ial en i onmen s, highligh ing he need o collec and secu ely
ansmi senso da a o u he p ocessing in cloud s o age o sma spaces.
In he con ex o he IoT pa adigm, a en ion o edge compu ing becomes essen ial
o add ess bo h secu i y and in elligence equi emen s. Besednyi e al. [
14
] p oposed an
edge compu ing model ha ocuses on ecei ing and p ocessing senso da a, u ilizing
specialized compu ing modules o ga he aw da a om mul iple senso s in he physical
en i onmen . Thei s udy highligh s he ad an ages o implemen ing local da a p ocessing
on edge o in e media e de ices, imp o ing secu i y and communica ion e iciency by
le e aging ad anced secu i y measu es and minimizing he ansmission o sensi i e da a.
This wo k ex ends beyond he exis ing li e a u e, p esen ing an empi ical s udy o
h ee ICPs: OPC-UA, Modbus, and E he ne /IP. I aims o answe esea ch ques ions abou
how hese p o ocols di e in e ms o pe o mance and complexi y o use om a so wa e
pe spec i e, and how can hei e ec i eness be empi ically e alua ed and compa ed.
The e alua ion has been conduc ed in he Ae onau ics Ad anced Manu ac u ing
Cen e [
15
] (o CFAA, o i s ini ials in Spanish), a esea ch cen e dedica ed o he de elop-
men o ad anced manu ac u ing echnologies o ae onau ical engine componen s and
o he ae ospace elemen s. The CFAA conduc s applied esea ch be ween Technology Readi-
ness Le els (TRL) 5 and 7 [
16
] wi h echnologies including high-p ecision machining [
17
],
b oaching [
18
], o addi i e manu ac u ing [
19
]. The CFAA has s a e-o - he-a machining
cen e s om a ious manu ac u e s, including Fago , Danoba , and He mle.
The emainde o his pape is s uc u ed as ollows: Sec ion 2desc ibes and compa es
he p o ocols s udied in his wo k, and Sec ion 3p esen s so wa e ools o enable da a
acquisi ion om gene al pu pose compu ing sys ems. Sec ion 4p esen s he esul s o a se
o es s ha assess he pe o mance o he p esen ed p o ocols, and inally, Sec ion 5d aws
some conclusions and ou lines u u e wo k.
2. Indus ial Communica ion P o ocols
This sec ion explains he p o ocols and connec ion s a egies used in indus ial commu-
nica ion, including examples o hei applica ion in he manu ac u ing indus y. The mos
common and widely employed p o ocols in indus y ha e been chosen [
20
], along wi h a
inal compa ison.
2.1. Modbus
Modbus is an ICP used o da a ans e be ween de ices in au oma ion and p ocess
con ol sys ems [
21
]. I ollows a clien /se e model, enabling communica ion be ween
de ices connec ed ac oss a ious ypes o buses o ne wo ks.
In o de o es ablish a Modbus connec ion, one de ice mus be con igu ed as a se e
and he o he as a clien . By ini ia ing a TCP/IP connec ion, he clien sends a eques
o he se e , which hen esponds by ansmi ing he eques ed in o ma ion h ough a
channel. This p o ocol employs a ious ypes o da a messages o ead o w i e in o ma ion
in compa ible de ices, wi h Modbus RTU being one o he mos common me hods o
se ial communica ion.
Senso s 2023,23, 5694 4 o 15
Modbus s ands ou o i s capabili y o connec wi h a wide ange o de ices, and high
eliabili y in da a ansmission. Fu he mo e, being an open-sou ce p o ocol, he e a e a
numbe o high-le el lib a ies o di e en p og amming languages.
Modbus TCP, being an olde indus ial p o ocol, has limi ed buil -in secu i y ea u es.
I lacks enc yp ion and au hen ica ion mechanisms by de aul , lea ing i suscep ible o
unau ho ized access and da a manipula ion. To enhance secu i y, implemen ing addi ional
measu es such as Vi ual P i a e Ne wo ks (VPNs) and applica ion-laye enc yp ion me h-
ods including T anspo Laye Secu i y (TLS) o Secu e Socke s Laye (SSL) can e ec i ely
p o ec Modbus TCP communica ions om po en ial h ea s.
In ecen yea s, e o s o enhance he secu i y o Modbus TCP ha e led o he de el-
opmen o he Modbus Secu i y p o ocol in 2018. Recen esea ch ocuses on s eng hening
Modbus TCP’s secu i y agains unau ho ized access. Fo ins ance, Ma ins and Vidal [
22
]
p oposed au hen ica ion and au ho iza ion unc ions by implemen ing use name and
passwo d based access con ol me hods o human use s wi h knowledge o indus ial au-
oma ion con ol sys ems (IACSs). Ano he s udy by de B i o and de Souza [
23
] in oduces
a es bed using he Modbus p o ocol o analyze cybe secu i y in nuclea powe plan s.
These ad ancemen s aim o add ess ulne abili ies and explo e me hods o secu ing
Modbus TCP communica ions.
Modbus is commonly used in he manu ac u ing indus y o ans e da a be ween
de ices such as PLC and HMI (Human–Machine In e ace) h ough he u iliza ion o sen-
so s. Fo example, Khuzya o e al. [
24
] p oposed a clien /se e app oach ha es ablishes
communica ion be ween a Siemens PLC and ield de ices using he Modbus p o ocol o
p ocess con ol sys ems. In ano he s udy, Li e al. [
25
] de eloped a digi al win capable
o de ec ing DoS a acks on Modbus TCP by using OpenPLC as a ool o i ualiza ion
o indus ial con ol sys ems. In he con ex o IIoT communica ion, Folgado e al. [
26
]
highligh ed he ad an ages o using ad anced eal- ime da a acquisi ion and moni o ing
sys ems, including he p ac ical implemen a ion o Modbus TCP, o enhancing he pe -
o mance and eliabili y o Polyme Elec oly e Memb ane (PEM) hyd ogen gene a o s in
indus ial applica ions.
2.2. P o ibus and P o ine
P o ibus is an open ield digi al ne wo k s anda d used o in e connec p ocess au oma-
ion componen s such as ield senso s, ac ua o s, and PLCs in indus ial en i onmen s [
27
].
The a chi ec u e o P o ibus is buil upon a clien /se e model.
P o ibus enables he se e , as he p ocess con olle , o supe ise communica ion
wi h clien s, including d i e s, mo o s, I/O (inpu /ou pu ) de ices, and obo s. In o de o
connec o a P o ibus de ice, i is essen ial o ha e an ope a ional and con igu ed ne wo k,
assign a de ice add ess, and es ablish a communica ion channel wi h a P o ibus se e ,
such as a PLC o a simila de ice. Once connec ed, he de ices can exchange da a and
commands seamlessly.
Howe e , wi h e ol ing indus ial ne wo king equi emen s, P o ibus has become ou -
da ed when compa ed o mode n ieldbus p o ocols such as Modbus TCP, E he ne /IP, and
P o ine . P o ine , an e he ne -based ieldbus wi h an open and s anda dized a chi ec u e,
o e s signi ican ad an ages o e i s p edecesso , including as e da a ansmission a es,
inc eased lexibili y, and imp o ed scalabili y [
28
]. The mig a ion om P o ibus o P o ine
has enabled indus ial sys ems o emb ace he bene i s o e he ne -based communica ion,
esul ing in highe e iciency, enhanced in e ope abili y, and s eamlined sys em in eg a ion.
P o ine has now es ablished i sel as he s anda d o eliable and e icien communica ion
in indus ial en i onmen s.
P o ibus, as an olde p o ocol, lacks na i e enc yp ion and au hen ica ion mechanisms
by de aul , lea ing i ulne able o secu i y b eaches. In con as , P o ine o e s ad anced
secu i y ea u es, including au hen ica ion h ough X.509 ce i ica es and use name/pass-
wo d, as well as enc yp ion using TLS o Secu e Real-Time T anspo P o ocol (SRTP).
Senso s 2023,23, 5694 5 o 15
Wi h hese measu es in place, P o ine ensu es da a con iden iali y and in eg i y, p o iding
obus p o ec ion agains unau ho ized access and da a ampe ing.
P o ibus and P o ine a e widely used in he manu ac u ing indus y. Fo example,
Gabo e al. [
29
] implemen ed he con ol o a mo o by es ablishing communica ion
be ween a Siemens S7-1200 PLC and an Ea on Va iable F equency D i e (VFD), which
is moni o ed by an HMI ha uses P o ibus. Ano he example is p esen ed by Kjellsson
e al. [
30
], who examined he in eg a ion o he WISA (Wi eless In e ace o Senso s
and Ac ua o s) concep in wi ed ield ne wo ks o ac o y au oma ion, bo h in P o ibus
and P o ine . Addi ionally, Xie [
31
] p oposed an in eg a ion a chi ec u e o P o ine and
OPC UA echnology, ocusing on he ans e o diagnos ic in o ma ion o manu ac u ing
execu ion sys ems. This highligh s he signi icance o P o ine diagnos ic in o ma ion in
implemen ing p edic i e main enance s a egies.
2.3. E he ne /IP
E he ne /IP is an ICP based on e he ne echnology ha enables eal- ime da a ans-
e be ween de ices o di e se manu ac u e s and echnologies [
32
]. I is based on a
clien /se e a chi ec u e and i is ex ensi ely deployed in con ol applica ions wi hin
p oduc ion plan s ha demand he ansmission o high-speed and high- olume da a.
To implemen E he ne /IP, a ious de ices including senso s, ac ua o s, and con-
olle s mus be connec ed o a common ne wo k and communica e wi h each o he o
coo dina e p oduc ion ope a ions. This equi es knowing he IP add esses and names o
hese de ices and con igu ing hem o communica e a a speci ic ime in e al. Then, a
TCP/IP connec ion is es ablished wi h he de ice o acili a e he exchange o I/O messages.
E he ne /IP p o ides se e al bene i s, such as high-speed da a ansmission, scalabili y
o in eg a ing a ex ensi e ange o de ices, and ease o con igu a ion and oubleshoo ing.
Mo eo e , as i is a s anda dized p o ocol, i is easie o main ain.
E he ne /IP o e s mo e obus secu i y ea u es compa ed o Modbus TCP. I suppo s
au hen ica ion mechanisms, including use name and passwo d based au hen ica ion, o
e i y he iden i y o de ices and use s. Addi ionally, E he ne /IP suppo s IPSec (In e ne
P o ocol Secu i y), which p o ides con iden iali y, in eg i y, and au hen ica ion o IP-
based communica ions. By implemen ing IPSec, da a exchanged be ween de ices can be
enc yp ed, p o ec ing i om unau ho ized access.
The e a e mul iple applica ions o his p o ocol in Indus y 4.0. Bello [
33
] highligh s
i s impo ance in au omo i e indus y communica ions. Addi ionally, Nguyen e al. [
34
]
p opose a no el eal- ime communica ion app oach based on E he ne (RTE he ne ) and
p esen an in as uc u e o con olle s a ions wi h he objec i e o op imizing da a
ansmission capaci y ac oss mul iple machines.
2.4. OPC-UA
OPC-UA is a c oss-pla o m communica ion p o ocol in ended o secu e and eliable
da a exchange in he indus ial au oma ion space [
35
]. An OPC a chi ec u e is composed o
one o mo e OPC se e s and OPC clien s.
OPC-UA allows a cons an da a low be ween mul iple de ices and con ol applica-
ions wi h limi ed es ic ions, as well as se ing as a means o communica ion be ween
Supe iso y Con ol and Da a Acquisi ion (SCADA) applica ions and senso s. Bidi ec ional
connec ions and pe sis en sessions a e essen ial o main aining ac i e and con inuous
communica ion be ween clien s and se e s. In e ms o cap u e equency, OPC-UA is
ypically used o moni o a educed se o a iables ( om 1 o 5).
OPC-UA is conside ed as he de ac o communica ion p o ocol o Indus y 4.0 [
36
].
I o e s bene i s such as high secu i y, eal- ime ansmission o la ge da a olumes, and
high scalabili y. I s echnological independence enables compa ibili y wi h de ices and
pla o ms om a ious manu ac u e s and ope a ing sys ems. Howe e , implemen ing
OPC-UA in en i onmen s wi h nume ous de ices can be complex and cos ly.
Senso s 2023,23, 5694 6 o 15
OPC-UA was designed wi h secu i y as a undamen al aspec , p o iding comp e-
hensi e secu i y ea u es. I suppo s anspo laye secu i y p o ocols such as TLS/SSL,
enabling enc yp ion and au hen ica ion o secu e da a ansmission. OPC-UA also in-
co po a es access con ol mechanisms, allowing adminis a o s o de ine de ailed access
policies o use s and de ices.
The adop ion o his p o ocol o e s ad an ages in implemen ing p edic i e main e-
nance in indus ial machine y. Fo example, Tapia e al. [
37
] implemen ed a moni o ing
pla o m ha used OPC-UA o acqui e da a om a 5-axis machining cen e and de ec
ou lie s in eal ime. Liu e al. [
38
] p oposed a pla o m ha in eg a es OPC-UA wi h MT-
Connec (manu ac u ing indus y s anda d) o enhance e ec i e communica ion be ween
cybe –physical machine ools and suppo in o med decision-making. In a s udy ocused
on IIoT, Gu ie ez-Gue e o and Holgado-Te iza [
39
] p oposed a no el mechanism o
au o-con igu ing OPC UA sys ems in indus ial en i onmen s. This mechanism allows
o sel -managed con igu a ion o e he Modbus p o ocol, au oma ing he se up o he
OPC-UA se e om PLC de ices connec ed o a basic E he ne ne wo k.
2.5. P o ocol Compa ison
Table 1p o ides a compa ison o he i e ICPs discussed abo e, in e ms o ans-
mission ange, equency, da a a e, and secu i y. As obse ed in he able, Modbus,
P o ibus, and P o ine p o ocols a e well-sui ed o local ne wo ks, whe eas E he ne /IP
and OPC-UA a e be e sui ed o wide a ea ne wo ks, wi h OPC-UA o e ing an unlimi ed
ansmission ange. E he ne /IP and P o ine ha e he highes equency, a ying be ween
1 and 100 MHz, and he highes da a a e, capable o eaching speeds o up o 1 Gbps.
Table 1. Indus ial communica ion p o ocols compa ison.
P o ocol Range F equency Da a Ra e (Mbps) Secu i y
Modbus Local/Wide A ea Ne wo ks 1–1000 Hz Up o 0.1 Mbps Low
P o ibus Local/Wide A ea Ne wo ks 1–16 MHz Up o 12 Mbps Low
P o ine Local/Wide A ea Ne wo ks 1–100 MHz Up o 1000 Mbps High
E he ne /IP Wide A ea Ne wo ks 1–100 MHz Up o 1000 Mbps Medium/High
OPC-UA Unlimi ed 1–10 kHz Up o 100 Mbps High
When selec ing an indus ial p o ocol o a speci ic applica ion, i is impo an o
conside ac o s such as ne wo k size, complexi y, numbe o de ices, and da a ansmission
olume. These cha ac e is ics a e key in de e mining he mos app op ia e p o ocol o he
speci ic scena io.
Figu e 2illus a es he usage pe cen ages o indus ial p o ocols based on a s udy
conduc ed by HMS Ne wo ks in 2019 [
40
]. In ha pa icula yea , indus ial e he ne
comp ised 59% o newly ins alled nodes, while ieldbuses cons i u ed 35% o indus ial
u iliza ion. E he ne /IP eme ged as he p edominan ne wo k, ep esen ing 15% o he o al
ins alla ions, whe eas Modbus TCP was u ilized in 4% o cases. Among ieldbuses, P o ibus
DP held he highes usage sha e, accoun ing o 10% o he o al. Addi ionally, he e was
a no iceable g ow h o 30% in he adop ion o wi eless echnologies. This inc ease can be
a ibu ed o he apid p og ess o he IoT and he p oli e a ion o mobile de ices a he
edge. The indus y has ecognized he nume ous ad an ages o wi eless communica ion,
including enhanced mobili y, lexibili y, and connec i i y. This g owing adop ion enables
eal- ime da a ansmission, and emo e moni o ing and con ol, leading o imp o ed
ope a ional e iciency and he c ea ion o new applica ions.
Senso s 2023,23, 5694 7 o 15
Figu e 2. Use o indus ial communica ion p o ocols in 2019 [40].
3. So wa e o Indus ial Da a Acquisi ion
This sec ion explo es wo da a acquisi ion me hods employed in big da a en i on-
men s, o e ing insigh s in o he ad an ages and d awbacks associa ed wi h he men ioned
so wa e ools.
3.1. ETL Tools
Ex ac , T ans o m, Load (ETL) ools a e so wa e pieces ha acili a e he p ocess
o ex ac ing da a om di e en sou ces, such as da abases, iles, o emo e loca ions,
ans o ming o manipula ing he da a acco ding o p ede ined ules o equi emen s, and
hen loading i in o a a ge des ina ion, such as a da a wa ehouse o a da abase. Some ETL
ools p o ide a isual in e ace o p og amming en i onmen ha enables use s o design,
schedule, and au oma e he da a in eg a ion wo k lows, ensu ing e icien , accu a e, and
scalable da a mo emen and ans o ma ion ac oss a ious sys ems and o ma s.
An example o a widely used ETL ool is Apache NiFi [
41
], which enables he use
o c ea e da a lows be ween di e en ypes o sys ems in a isual way. I p o ides a
G aphical Use In e ace (GUI) whe e use s can design da a pipelines by connec ing di e -
en p ocesso s, which a e he basic building blocks o NiFi. Each p ocesso o e s di e en
unc ionali ies such as da a inges ion, il e ing, ans o ma ion, and da a o wa ding. NiFi
o e s a wide ange o p e-buil p ocesso s, and use s can also c ea e cus om p ocesso s o
add ess speci ic da a p ocessing equi emen s.
Apache NiFi o e s se e al ad an ages o da a managemen . I is highly scalable,
allowing e icien handling o la ge da a olumes. The da a p o enance enables acking
and audi ing o da a, enhancing da a go e nance. Addi ionally, NiFi p o ides obus
au hen ica ion and enc yp ion mechanisms o ensu e da a secu i y.
A limi a ion o Apache NiFi is i s dependence and eliance on p ocesso s, which can
impac da a p ocessing unc ionali y based on hei a ailabili y and compa ibili y. Complex
use cases in ol ing in ica e ans o ma ions may also equi e addi ional con igu a ion and
de elopmen e o s.
3.2. Coding En i onmen s
As an al e na i e o o - he-shel ools, p ac i ione s can c ea e cus om ways o ex ac
da a o machine ools using coding en i onmen s. A e y popula one is Py hon, a e sa ile
Senso s 2023,23, 5694 8 o 15
p og amming language and en i onmen ha p o ides a ange o lib a ies and ools o
ex ac ing da a om indus ial communica ion p o ocols
As an example, and in he con ex o his wo k, Snap7 is a Py hon lib a y ha enables
communica ion wi h PLCs h ough he Siemens S7 (S ep7) p o ocol [
42
]. S7 is designed o
wo k wi h di e en ICP, which a e selec ed based on he speci ic communica ion ha dwa e
used. Commonly employed p o ocols o S7 include P o ibus, P o ine , and E he ne /IP.
Ano he commonly used lib a y o da a inges ion is pyModbusTCP [
43
], which
p o ides a Py hon implemen a ion o he Modbus TCP p o ocol. Wi h i s use - iendly
classes and unc ions, i acili a es in e ac ion wi h Modbus TCP de ices, allowing easy
eading and w i ing o da a.
Py hon’s well-documen ed lib a ies o ICP p o ide de elope s e icien ools o
ex ac ing and p ocessing da a in big da a en i onmen s. Fu he mo e, Py hon is highly
a o ed due o i s simplici y, ease o use, and open-sou ce na u e, o e ing he a ailabili y o
lib a ies o a ious applica ions. Howe e , a d awback o Py hon can be i s pe o mance;
gi en i s na u e as an in e p e ed language, some Py hon en i onmen s do no a ain as
much pe o mance om he compu ing machines as compiled languages. Ne e heless,
a way o add ess his issue is o use en i onmen s such as Cy hon, which allow de el-
ope s o w i e C ex ensions o Py hon, enhancing he pe o mance o compu a ionally
in ensi e asks.
4. Resul s
In his sec ion, we p esen he esul s ob ained om he empi ical e alua ion o
h ee communica ion p o ocols. The es ing me hodology is desc ibed in Sec ion 4.1 and
Sec ion 4.2 p esen s expe imen s e alua ing he pe o mance o he p o ocols in e ms
o acquisi ion a es and CPU and RAM usage. Sec ion 4.3 p o ides an analysis o hei
usage complexi y om he so wa e pe spec i e, including code samples om he Py hon
lib a ies in use.
4.1. Expe imen al Se up
In his sec ion, we p esen an o e iew o he es ing me hodology, including he
indus ial machines u ilized, hei cha ac e is ics, he a iables ob ained om each machine,
and he app oach aken o es ablish he connec ion wi h each p o ocol.
As shown in Figu e 3, he ex ac ion o a iables om he PLC is ca ied ou by
es ablishing a di ec connec ion wi h he machine using an e he ne cable. This equi es
connec ing he cable o a de ice wi h a Py hon en i onmen wi h he necessa y lib a ies o a
NiFi en i onmen . The es ing phase in ol ed e alua ing h ee p o ocols on h ee di e en
machines. Speci ically, Modbus TCP was used o e ie e a iables om a b oaching
machine, E he ne /IP was employed o a u ning machine, and OPC-UA enabled a iable
ex ac ion om a milling machine.
Figu e 3. Connec ion be ween manu ac u ing machines and communica ion p o ocols.
Senso s 2023,23, 5694 9 o 15
4.1.1. Communica ion be ween Modbus TCP and a B oaching Machine
This sec ion p o ides an o e iew o he da a ex ac ion p ocess om an EKIN
™
A218
b oaching machine using he pyModbusTCP ( e sion 0.1.10) Py hon lib a y. The A218 is
an elec omechanical b oaching machine designed o ex e nal su ace applica ions [
44
].
Unlike o he b oaching machines, he cu ing ool emains s a ic on his machine. A he
same ime, he o a y indexing able, along wi h he wo kpiece, mo es along he en i e
machine’s Z-axis, allowing o a highe cu ing speed (Vc). One no able ad an age o
his machine is i s abili y o ex ac mo o in o ma ion and moni o he cu ing p ocess,
p o iding aluable insigh s o analysis.
The whole sys em is con olled by he FAGOR
®
8070 compu e nume ical con ol
(CNC) so wa e, which o e sees he cu ing p ocess. In he same way, i enables he
collec ion o da a on he engine’s condi ion, ensu ing ha he da a a e collec ed a a
equency equal o o g ea e han he closed-loop con ol cycle.
When connec ing o he CNC, i is impo an o ensu e ha i is wi hin he same
ne wo k ange. Nex , he IP add ess o he CNC and he po o Modbus TCP (502)
should be speci ied. A e iden i ying he manu ac u e ’s inpu egis e add esses and hei
co esponding da a ypes, he ange o add esses is de ined, ensu ing he s a ing and
ending add esses o he egis e s o be ead a e p o ided.
Some o he mos ele an moni o ing a iables in he A218 b oaching machine a e:
• Z-axis posi ion.
• B oach leng h.
• Cu en slo angle.
• Cu ing speed (Vc).
4.1.2. Communica ion be ween Snap7 and a Tu ning Machine
In his sec ion, we will p o ide an o e iew o he da a ex ac ion p ocess om a
u ning machine’s PLC using he Snap7 ( e sion 1.3) Py hon lib a y. Speci ically, we will
ocus on u ilizing E he ne /IP p o ocol o ob ain da a om he PLC.
The a iables will be ex ac ed om a Danoba
™
TV-1500 machining cen e [
45
].
This cen e ea u es a e ical u ning la he capable o pe o ming p ecise ope a ions includ-
ing u ning, g inding, and measu ing. The e ical la he s ands ou o i s high dimensional
s abili y and high damping coe icien , ensu ing p ecision in machining p ocesses. The ma-
chine has a Siemens
®
Sinume ik 840D SL CNC in eg a ed wi h a Siemens
®
Sima ic S7-300
PLC ha , among o he s, collec s moni o ing da a in he o m o a se o a iables.
To es ablish a connec ion wi h he PLC using E he ne /IP, i is necessa y o ensu e
ha he de ices a e in he same ne wo k ange. Then, he IP add ess, ack numbe , and slo
numbe o he PLC need o be de ined. A e es ablishing he connec ion, i is possible o
ead da a om a speci ic da a block (DB) by speci ying he block numbe , s a ing add ess,
and da a size. Fo his pu pose, i is essen ial o consul he manu ac u e ega ding he
de ini ion o he DBs.
Some o he mos ele an moni o ing a iables in he TV-1500 a e:
• X- and Z-axes posi ion.
• Spindle axis posi ion.
• Spindle o a ional speed.
• Spindle powe .
4.1.3. Communica ion be ween OPC-UA and a Milling Machine
This sec ion ou lines he p ocess o ex ac ing da a om an Iba mia
™
THR 16 [
46
]
i e-axis milling machine PLC using OPC-UA. The THR16 is a machining cen e ha
combines di e en echnologies in a single machine: milling, d illing, u ning, gea cu ing,
and g inding. I is conside ed a Mul ip ocess machine, as i allows machining di e en
ypes o pieces wi h he same ool-se . This educes he quan i y o pa s ha mus be
manu ac u ed in ba ches, which sho ens he p oduc ion li e cycle and educes he amoun
o shi s be ween machines in a ac o y.
