On September 16, 2025 I presented a Keynote Address at the 6th PS2 organized by Omicron.
Click HERE for accessing my slides [PDF, 9 MB]
IEC 61850, IEC 61400-25, IEC 61970 (CIM), IEC 60870-5, DNP3, IEC 62351 (Security), ...
On September 16, 2025 I presented a Keynote Address at the 6th PS2 organized by Omicron.
Click HERE for accessing my slides [PDF, 9 MB]
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:
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.
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 ...