What does OPC UA stand for ? how does opc UA work

today we are going to learn what is OPC UA before we understand OPC UA & what does OPC UA stand for ?

to understand that concept it’s important to understand the earlier version of OPC

OPC Classic & OPC DA

before the existence of OPC Classic & OPC DA

if you have Allen Bradly PLC . you wanna talk to One HMI

here there was only one way HMI should have a specific driver for that Allen Bradley PLC

similarly if you got another PLC which is from Siemens if you want to communicate that PLC to that HMI you should have a specific drivers of that Siemens specific model

so this is a pick challenge you can see right now because you know there are a lot of Brands and
well so it’s really tricky and it’s very tough to keep a record of every possible brand and their models and to fix that

problem actually we got OPC DA

In OPC DA now you got a standard interface which is your OPC server
If your OPC client which is your HMI supports that OPC Server if your Allen Bradley PLC also
supports that you don’t need to worry about the drivers

if you go to Siemens PLC if you want to communicate that specific PLC to HMI also you don’t need to keep a record of that specific driver in your HMI

OPC DA technology which is one of the very helpful thing which actually helps you to communicate with different vendors

OPC classic always uses Windows environment your OPC server should have a Windows and your OPC client which is your HMI should have a Windows otherwise they can’t use OPC

before defining OPC it’s very important to understand what is com or component object model

it’s a technology introduced by Microsoft to share the data between different applications running on the same system but what if if you got two

different systems and they are on a network connected with each other there is one application running here and one application running there

and if they want to share the data with each other they would be relying on a technology which is called DCOM or distributed component object Model

What does OPC UA stand for ?

now we can easily Define what is OPC

OPC is ole for process control now it would be very easy for me to Define ole is object linking and embedding

Ole is actually based on Windows com standard

this is a mechanism how different applications actually share the data in Windows environment there’s one problem in OPC

it only Supports Windows environment and that’s what actually lead us to the next thing which is OPC UA

So OPC UA is actually next generation of OPC technology which is more secure as compared to the OPC classic because OPC in OPC classic security was not a big consideration at that time

So OPC UA is a more secure open reliable mechanism for transferring information between servers and client

it provides better security and a more complete information model than original OPC DA

OPC UA actually Supports Apple environment it also supports Linux plus Windows environment

what are the component in OPC architecture

everything starts from the field connection your OPC technology supports all the connections like your instruments modbus can bus profibus vfd PLC DCS controller

OPC UA server is a software that implements the OPC standard and thus provides the data to all client applications

OPC servers are actually provided by different companies

you have OPC server coming from a different DCS vendors like Honeywell

when we talk about the field data it actually comes to your OPC server which have all the information of this of the data coming from the field and then you got in OPC clients

what are the OPC clients OPC

OPC client software is any program that need to connect to the hardware such as HMI, Raspberry Pi, MES systems

OPC UA you have information about everything units flow set points instrument configuration parameter range sensor types all that sort of information is provided in OPC UA

what happens actually your OPC client would request the data
1)your OPC server would respond back to that OPC client
2)whatsoever actions are possible read and write 3)OPC UA server requires certificates to ensure trusted communication between OPC UA clients

by that way you are making sure the security feature as well data in OPC UA communication is encrypted there is a big misunderstanding that exists

it have a complex information model that grabs all the properties along with the values like
units set points and instrument configuration parameters ranges and Engineering units

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