What is a model in the context of IEC 61850?

A model is a model is a model ... huch.

The question is: What does a model provide? In short: It provides an external visible PATH to an actual value of something, e.g., a voltage or temperature. A model of my home is not something where I can life in! It shows where the rooms, stairs, ... are ... 

The leaves (or end points) of the model in the IEC 61850 TREE (of a model) are NOT where the actual value reside! Basic Data Attribute (BDA) in IEC 61850 are the leaves of the trees. 

Just a minor comment on the BDA: I found this: "This is the lowest level, where the actual value resides." IEC 61850 defines models that hide the storage location of an actual value. The BDA is a PATH to the actual value. The value resides "behind" that model. The BDA holds an externally non-visible or non-accessible reference to the actual measurement value or status.

When reading the current value of the phase A of the MODEL MMXU1 you send a read request with the PATH: "LD/MMXU1.A.phsA.cVal.mag.f". This PATH is translated into the direct or indirect storage location of a specific IED. How that is implemented, depends on the architecture of the interface and application software. It may even be mapped to an underlying fieldbus specific address (e.g., Modbus coil 2828). When the read request is received, the IED uses Modbus to read the actual value from coil 2828. In this case the actual value resides beyond the IED with its MODEL. The IED needs a non-visible specific mapping from the PATH to the Modbus register.

The models in IEC 61850 describe a virtual world in the following sense:

If it's there and you can see it         It's REAL
If it's there and you can't see it         It's TRANSPARENT
If it's not there and you can see it It's VIRTUAL
If it's not there and you can't see it It's GONE
Roy Wills

I hope that helps to understand the Models in IEC 61850.

This virtualization has an impact on how an IEC 61850 Stack (is not defined in IEC 61850 what a stack is) you purchase maps the leaves of the model to the location of your actual values.

The 30 Year Anniversary of IEC 61850 at Omicron in Klaus (Austria) on September 24, 2025, was a BIG success

The IEC 61850 Community has celebrated the 30 Year Anniversary at Omicron in Klaus (Austria) on September 24, 2025, was really a BIG success. Thanks to everybody that contributed to this success: Omicron employees, IEC TC 57 management, IEC TC 57 WG 10 and WG 19 members, many old friends from all-over. Some photos are already posted at LinkedIn ...

I was asked to tell the IEC 61850 Community the history of the standardization process starting in the 1980s with the fight Tokenbus versus Ethernet, MMS versus FMS, ... x versus y, ...

Click HERE to download my presentation [pdf, 6 MB] 

You can see me on the stage during my presentation:

The event was a great opportunity to meet people I have not met for years, e.g., George Schimmel (Tamarack, later TMW):

I guess I met George the first time in 1985 at the GM Techcenter in Warren (Michigan) ... MAP project.

René Troost and Alain Stuivenvolt from The Netherlands are so smart that they were able to move the stack of 7 layers of the Tower of Hanoi from one stick to another - well done.

On the group photo you find me in the first row/center:

I am still wondering that a lot of experts talk about IEC 61850 as a standard for substations! We are shaping more than the future of digital substations ... after the "Klaus Agreement" (see meeting minutes of the Task Force IEC 61850-8-3) we expect that IEC 61850 will be shaping the future of electric power systems far beyond substations as I discussed some 20 years ago: 

Check HERE a paper on this topic I published in the year 2008.

Some Hints on the use of Wireshark for IEC 61850-8-1 (MMS)

Please note the following preferences ... and have fun:

Version I used today:

Set the mms filter so see mms/IEC61850 only:

In case the MMS server is using a different port number: e.g., 12001 instead of standard port 102:

Analyze/Decode/ set other port number accordingly:

Check if presentation users context is correct:

Analyzing MMS/ASN.1/BER is sometimes tricky ... here is an example I figured out the other day ... if the length of a value is three (3) octets then the ASN.1 BER encoded message should indicate a length of 3 ... not 2 ... one single error in the length could damage the communication ...