Sunday, February 26, 2017

The Most Important Difference Between MTConnect and OPC - *HOW* You Get The Data

There are some key differences between MTConnect and OPC UA where many folks get confused that I am going to clarify.  I have had this conversation countless times and had one this past Friday and thought it was time for a blog post on it.  Let me make sure everyone understands that MTConnect and OPC are working together and this is an educational blog to clarify the key differences between the two and not a battle cry. 

Here's the net/net or punch line. 

THE single MOST important difference MTConnect and OPC UA is HOW you get the data which came about directly because of HOW the MTConnect Institute organized the MTConnect Technical Advisory Group (MTCTAG) to create the COMMON dictionary of terms.  Don't worry, I will expand on this :-)

First some background.  In general, OPC is used for process manufacturing and MTConnect is used for discrete manufacturing.   Process manufacturing is where a big bale of coffee beans comes in the left end of the plant and small k-cups come out the right end of the plant.  Discrete manufacturing is where larger pieces of metal go in the left end of the plant and smaller pieces come out the right end of the plant and those smaller pieces are called finished parts such as landing gear for a jet.

Sometimes it is easy to get caught in the low level technical details of MTConnect and OPC UA and miss the most important differences. 
The MTCTAG  was modeled after how the computer industry works on standards where companies in the same market come together to work on the standard.  The idea is that the companies work together on a common standard (interface for example) so they can compete on the best implementation.
Specifically, the MTConnect Machine Tool Working Group had/has companies such as Mazak, Okuma, Doosan, DMG Mori-Seiki, FANUC, MAG, Makino, GF AgieCharmilles and many others that came together to create a COMMON dictionary of terms they ALL would agree on.   What is a common dictionary and why does it matter?  Think of a plant floor as the United Nations of machine tools with each speaking a different language.  MTConnect is the common language, but EVEN more importantly it has the common definition of terms that is the dictionary.  WHY is this so important?  Because the companies listed ALL agreed on WHAT the terms will be CALLED and EXACTLY what they MEAN.  For example, there are not 11 different versions of spindle speed -- there is ONE.  This is a BIG, BIG deal! This means that applications can be written to MTConnect and NOT worry about what the machine tool is or what device is on the plant floor.  
Most importantly for manufacturers MTConnect means I have CHOICE.  When a shop floor monitoring software speaks to a machine tool or a device using MTConnect, it is the equivalent of using Bluetooth.  Both the machine tool/device and the application speak MTConnect and it just works.  Since MTConnect is based on http and XML, which is the linga francua or the standard language of the Internet, any software package that was not written in a cave can easily speak to a MTConnect enabled device. This is why the catch phrase (created by Doug Woods President of AMT) for MTConnect is, "Different Devices, Common Connection".
The single question to ask those who say, "OPC is the same as MTConnect", is "MTConnect has a Machine Tool Working Group, please tell me about the same working group at OPC?"  
The answer is that there  is NO Machine Tool Working Group in OPC that has agreed upon a COMMON dictionary.
Let me repeat this fact.
The answer is that there  is NO Machine Tool Working Group in OPC that has agreed upon a COMMON dictionary.
It is always a challenge coming up with the appropriate analogy.  In this case I will use a simile to hopefully explain the differences and illuminate where the confusion can occur either on purpose or by accident by those on the OPC side of the house when they are comparing MTConnect to OPC.
The photo below is a box with 12 gauge wire coming out of it.  There is a copper wire, a white wire and black wire.  This is OPC.  OPC provides the plumbing or the wiring, but it is up to you to determine exactly how things will be put together.

 The photo below is your typical electrical outlet in a house in North America.  Behind the outlet cover are the same copper wire, a white wire and black wire that you see in the electrical box above.  The MTConnect outlet INCLUDES a NEMA 5-15R (receptacle) that provides 120 volts at 60 hertz with a max of 15 amps.  This is MTConnect.  MTConnect provides the plumbing or the wiring, but in addition, it CLEARLY defines WHAT you will get when you plug into it. 

The applications are what you "plug" into an MTConnect machine tool or sensor.

 This is where folks in the OPC world can purposely obfuscate what is really going on or they simply do not understand what is going on with MTConnect and muddy the waters.   Someone from the OPC side of the house can say, "well, we provide electricity (machine tool data) so why do you care HOW you get it as long as you get it?"   It is the classic false choice version of black and white logic.

The reason manufacturers CARE is because they want MORE than just the wiring.  They do not want to figure out what type of plug, voltage, amperage and AC or DC current (machine tool or sensor data ) they need to use, they simply want to have a common standard they can easily plug into to speak to their many electrical appliances (applications).

Can I use OPC for the world of discrete manufacturing?  It begs the question, can I create my own outlets to use for my own appliances that are wired my unique way?  Sure, but WHY when MTConnect is elegant in its simplicity and is the de facto standard for discreet manufacturing interconnectivity? 

Let me say it again, there  is NO Machine Tool Working Group in OPC that has agreed upon a COMMON dictionary.

The goal of MTConnectOpcUa is to have a companion spec to ensure interoperability, but let's not forget MTConnect's secret sauce - the machine tool industry companies and others who came together to create an open source, free to use and free to deploy interconnectivity standard WITH a COMMON dictionary.
NOTE: For a 10 minute webinar on MTConnect with more details on exactly how this works, please go to my blog entry here called The Three "A"s of MTConnect - the Adapter, Agent and Application and watch the video I created.
It is worth noting that MTConnect is also extensible so that companies have the ability to add their own dictionary where they have capabilities which are outside of the standard dictionary.
ALL of these groups were led by the MTConnect Institute which has been funded for many millions of by AMT - The Association For Manufacturing Technology as well as other important companies.
I wanted to make sure everyone understands the most important differences between the two connectivity standards, but please do not take this the wrong way as I am a big fan of OPC and the OPC Foundation, as well as Tom Burke, but again, there are key differences.  

Below is information on MTConnectOpcUa - the companion specification for both organizations.

On September 16th, 2010 the MTConnect Institute and the OPC Foundation announced MTConnectOpcUA:

 "Chicago, Il. … Today, September 16, 2010, at the International Manufacturing Technology Show, the OPC Foundation and the MTConnect® Institute are announcing a joint Memorandum of Understanding. OPC and MTConnect will cooperate in developing standards called MTConnectOpcUa. MTConnectOpcUa is a set of companion specifications to ensure interoperability and consistency between MTConnect specifications and OPC specifications, as well as the manufacturing technology equipment, devices, software or other products that implement those standards.

Tom Burke, President and Chairman of the Board for the OPC Foundation, stated, “MTConnect & OPC collaborating will provide the necessary infrastructure to revolutionize interoperability for the complete spectrum of manufacturing technology, by leveraging the standards of both organizations, evolving the technology that has already been well accepted and adopted by the suppliers.” Dave Edstrom, President and Chairman of the Board for the MTConnect Institute has stated, “This is not just a win for MTConnect and OPC, this is a huge step forward for manufacturing interoperability around the globe.”

Any questions or comments, please use the comment section to share your thoughts.

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