is OPC UA the future of IIoT answering your questions question number three
take zero all right so the last question on my answer for now is you want to read
the question from the guy alright so the question was can you please come make a
video that compares PLC versus SCADA versus DCS as how it pertains to OPC UA
all right so in order to do that I gotta define these things all right so this is
actually very simple so our PLC is our programmable logic
controller out in the field the programmable logic controller has IO
inputs and outputs it's got a little processor running on it it's got some
software running generally you can connect to it and you can write a
control program that basically can read inputs and based on certain conditions
make changes to outputs right that's your PLC the SCADA system supervisory
control and data acquisition is a software layer that is designed to
centrally control and acquire data from many plcs ok so I may have my SCADA
system here my SCADA may talk to another PLC the big thing
that SCADA does is it gives you control and it gives you alarming that's really
the big thing that skated us is it it tells us when we have a problem
but it's central supervisory control and data acquisition is central dcs is very
similar to SCADA but think of it as proprietary ok
my SCADA system if I buy an off-the-shelf piece of SCADA software it
generally doesn't care who the manufacturer of this Hardware in the
field is ok it'll can talk to Allen-Bradley he can talk to Siemens it could
talk to Emerson talk to anything right the SCADA software is generally open and
it can talk to anything ok a dcs system is generally in most cases it's
processed specific and it's all of this stuff turnkey process specific so a dcs
system dist a distributed control system has a SCADA component ok it has a SCADA
component it has a PLC and oftentimes they call it a
either a RIO and RTU or a PLC it has a hardware component okay out in the field
most of the time that hardware in the field also talks to one another directly
so I may have a RIO a remote i/o card that's at the beginning of my process
and one halfway through my process another one further up from my process
there's some intelligence going on some i/o some intelligence going on on the
edge and then I have a massive controller in a control room that's
generally between the SCADA layer this is where the process control is taking
place this is where the program is running
and then my SCADA layer is really a node in the system okay so in distributed
control systems I may buy a DCS from ABB so for example in the steel in the steel
industry you use distributed control in your rolling mill because the technology
required the program required to run a rolling mill to turn a big billet into
rebar is millions of lines of automation code so what happens is ABB writes the
code one time you buy the distributed control system didn't they install all
the i/o they install the process control center they installed the SCADA
interface in the control room then they connect all that together and
then they add in some custom stuff oh I might add in some additional i/o to
turn-to-turn a water valve on here and there and you can add in custom process
control but with a distributed control system you almost always come with a
prepackaged program in that DCS to run your process and then you kind of add on
to it with PLC's and SCADA system think of them as blank slates right when I buy
an allen bradley control logics it doesn't have a program on it I can take
a program I've already written and put it on there or I can just write a new
one from scratch which is the way it normally works a distributed control
system can complete completely blank but in this day and age normally it does not
normally the DCS comes with the program to run your process already loaded on to
it that and here's the reason you use a distributed control system is these
almost always talk to one they're over a super high-speed field
bus okay so generally these connections are not direct copper connections and
they're not over Ethernet and they're not over fiber most of the time the
SCADA control unit and all your remote IOs and your process controllers are
connected over some type of field bus so think of DC s as a turnkey solution that
you can add on to to control your process and that turnkey solution
includes the SCADA component but let's say I add a new process to my plant so I
add in I install a new scale okay cuz I want to wait rail cars or something so I
add a new PLC and I've got a rail car that I want away okay in this scale this
Mettler Toledo scale comes up into that PLC most of the time you are not going
to add the SCADA interface to the DCs SCADA system why because it takes too
long to do it right you can yeah and here's why because you know the
companies that make DCs systems like ABB there are drivers that give us the
ability to talk from our SCADA system through for example cap wear to their
field bus system okay so the answer that's the difference the difference is
is that think of SCADA in plc as the blank slate the open architecture and
think of dcs as the turnkey solution but they if we were to Venn diagram their
functionalities the two circles would nearly stand right on top of one another
a car would be a dcs they eat the electronic control model module the ECM
module the flow control module the exhaust control module those are all
distributed control systems for your car the unit itself whatever they call it
you know like my Cadillac they call it something linked that is the dcs for my
Cadillac right on Tesla Tesla is a to all Tesla vehicles are distributed
control systems okay whereas the PLC is the actual brick it's the hardware and
the SCADA system is the piece of software the distributed control system
is the completed solution automation kit would be more plc scada
like you can kind of build your own correct that's exactly it yeah plc scada
would be more like Lego or minecraft think of it as minecraft. PLC SCADA is
like minecraft distributed control system is going to be like Mario level
builder it comes prepackaged and ready to go but you can build your own levels
if you want to yeah allen-bradley spam packs is another good
in fact Alan Bradley's plant packs was a approach at answering DCs for for a
labrat for rock well anyway that was a really good question
and thanks for watching