What is IEC 61850-8-1 MMS Compared to IEC 61850-8-3 DMS?

The paper "The Standard Message Specification for Industrial Automation Systems ISO 9506 (MMS)" has been downloaded 6,691 times from the ResearchGate ... seems to be an interesting document. 

Now, since we are working on a new protocol standard for IEC 61850-7-2 Client/Server communication (IEC 61850-8-3, DMS, Direct Message Specification), the question is: What is the difference between MMS and DMS?

Here are some answers:

DMS will be an alternative protocol for MMS ... with WebSocket connectivity, ASN.1 message schema, ASN.1 JER JSON encoding, ... very simple ... a straight forward from IEC 61850-7-2 ACSI (abstract messages) to concrete messages ... 1:1 ... no tricks ...

There are a few crucial aspects: (1) MMS as a standard that needs outdated OSI upper layers, (2) MMS is very complex and does not easily fit for IEC 61850-7-2 ACSI ... needs a tricks mapping to MMS in IEC 61850-8-1, (3) DMS communicates over WebSockets (bidirectional), (4) DMS uses JSON for message encoding (or DER binary) many tools are available, (5) the message schema of DMS is far simpler than the MMS message schema ... even both are using ASN.1 as schema notation, (6) MMS is not a good friend of many experts, (7) the Proof of Concept for RTI2 (Netherlands DSOs) is the basis for IEC 61850-8-3 ... and available at GitHub ...

From an system point of view (engineering, SCL, Models, abstract services, ... application functions, ...) there is no difference between the two protocols. From a smart implementation point of view the "stacks" could have an API that is independent of the protocols. There needs to be a tiny layer that decides if, e.g., a Report (with the payload from the application models) is wrapped with MMS or DMS ... for DMS there are two options: JER (JSON) and DER (binary) ... from a DMS stack point of view there is one line of code (!!) that is needed to encode in JSON or binary ...

Of course, the MMS message syntax and encoding are not compatible with DMS message syntax and encoding. BUT: they both carry the same payload!! ... thanks to the huge list of standardized "Signals" (models).

Both solutions run on TCP/IP ... there may be multi-protocol IEDs available some time down the road ... as we see today that many IEDs are supporting multiple protocols ... 

People asked me: Why did you not have this solution developed earlier?!? I developed something with my granddaughter when she did her Bachelor at KIT ... check my blog with some historical discussions

IEC published the Committee Draft (57/2980/CD) on IEC 61850-8-3

The next step of the publication of IEC 61850-8-3 has been reached

Yesterday (2026-09-04) IEC published the Committee Draft (57/2980/CD) on

"Communication networks and systems for power utility automation –
Part 8-3: Specific Communication Service Mapping (SCSM) –
Mapping to Direct Message Specification (DMS), JSON Encoding Rules, and WebSockets"

The commenting period closes on 2026-10-30 ... very soon.

All experts that are members of the IEC TC 57 National Committees can access the document and provide comments online.

My experience with the editing processing tool (OSD - Online Standards Development) is very positive: After I finished the editing on Monday (2026-08-31) IEC could easily publish the CD ... the document follows automatically the format of IEC ... because it is an IEC (ISO) tool ... perfect.

The crucial definition is the ASN.1 message schema that is used to code and decode messages (see see below for a link to the ASN.1 schema used in the RTI2 open-source software):

The committee draft (57/2980/CD) is based on the Netherlands Netbeheers Proof of Concept for RTI2 (real-time interface). Netbeheer is supporting the implementation as open-source software under GitHub. The message syntax of the committee draft is the latest ASN.1 module. The ASN.1 version at GitHub is a pre-version of the official version:
General: https://github.com/Netbeheer-Nederland/iec61850-websocket

Direct Access to the ASN.1 Schema: https://github.com/Netbeheer-Nederland/iec61850-websocket/blob/main/src/ws61850/asn1/schema/ws_iec61850_tpaa_full.asn

Please check my blog for additional information on IEC 61850-8-3.
Any question? Please let me know.

The PAC World Magazine Reports From the 30 Year Anniversary of IEC 61850 in September 2025

The 30 year anniversary of IEC 61850 in September 2025 was a big success.

The report mentions me: "The presentations were bracketed by the first one from Karlheinz Schwarz about how all of this started in the past Millenium ..."

I am very thankful for the invitation by Dr. Fred Steinhauser (Omicron) to speak about the history ... 

Click HERE for the Report in the PACW.

Click HERE for more photos and a link to my "Millenium" presentation.

When browsing the Web, I see many more papers, reports, posts, ... on IEC 61850 for substations and for applications beyond substations.

More to come: With IEC 61850-8-3

New Work Item Proposal on IEC 61850-8-3 has been accepted by 95 % of the TC 57 National Committees

In December 2025 the NWIP (57/2866/NP - proposed project number: IEC 61850-8-3) was published for voting and comments:
https://blog.nettedautomation.com/2025/12/long-awaited-christmas-gift-for-smarter.html

Today we are happy that the NWIP has been approved by IEC - only one country disagreed in the voting process.

IEC 61850-8-3
Communication networks and systems for power utility automation –
Specific Communication Service Mapping (SCSM) –
Mapping to Direct Message Specification (DMS), JSON Encoding Rules, and WebSockets 

The result of this work will very likely change the usability of IEC 61850 outside substations.

Stay tuned to follow the progress.

In order to explain details of the new approach to be used for the new work item proposal IEC 61850-8-3 I have produced a 17 minute video (2026-05-13).

Long Awaited Christmas Gift For Smart(er) Grids - IEC 61850-8-3 is on its Way

In order to explain details of the new approach to be used for the new work item proposal IEC 61850-8-3 I have produced a 17 minute video. (2026-05-13)

IEC TC 57 just published a long awaited and crucial new work item proposal: 

57/2866/NP - proposed project number: 61850-8-3

Communication networks and systems for power utility automation –
Specific Communication Service Mapping (SCSM) –
Mapping to Direct Message Specification (DMS),
JSON Encoding Rules, and WebSockets 

Closing date for voting on the NP: 2026-03-06

"IEC 61850-8-3 Ed.1 defines the direct mapping of the client/server services of the ACSI (Abstract Communication Service Interface) defined in IEC 61850-7-2. Direct mapping means that for every abstract client/server service of the ACSI a concrete message schema (for the request and the response) is defined in ASN.1 (Abstract Syntax Notation One). ...

The encoding of the messages according to IEC 61850-8-3 is using the ASN.1 JER (JSON Encoding Rule, ISO/IEC 8825-8:2021). The messages are exchanged through WebSocket (RFC 6455, The WebSocket Protocol). WebSocket is a communication protocol that enables a persistent, full-duplex communication channel over a single TCP connection, allowing both the client and server to send data to each other at any time. This differs from the standard HTTP request-response model, making it ideal for real-time applications."

Please contact your national IEC TC 57 committee for a copy of the NP.

The main differences between IEC 61850-8-1/8-2 and 8-3 are shown in the following table:

and here:

Enjoy!

Click HERE for additional information that discusses the need for a modern messaging solution ...

I look forward to continuing the editing work of this new part of IEC 61850. This closes the circle of my contribution to communication protocols: starting in the mid 1980s with MMS (base for IEC 61850-8-1/8-2) and now (40+ years later) involved in a modern approach using web technologies ... Wow ...

This NP is the result of a Proof of Concept (PoC) initiated and managed by the Netherlands Distribution System Operators (Netbeheer). I played a little role in the implementation of this PoC. The PoC demonstrated the great benefit that can be harvested from the solution!

It is very likely that this part IEC 61850-8-3 (once it is finished) will accelerate the application of IEC 61850 outside the substation domain. I have discussed IEC 61850 outside of substations for many years ... Let me know what you think.

I wish you a merry Christmas and the best for the year 2026.

UCAIUG Webinar on The Dutch IEC 61850 DSO-DER Realtime Interface: Practical Insights and Experiences

The famous UCA International Users Group invites you to attend a very interesting Webinar conducted by René Troost (Grid Strategist) at Stedin (Netherlands):

“The Dutch IEC 61850 DSO-DER Realtime Interface: Practical Insights and Experiences”

René serves as a Grid Strategist at Stedin, a major Distribution System Operator (DSO) in the Netherlands. In addition to his role at Stedin, he actively participates in and leads nationwide projects. 

Date: 2 October 2025
16:00 - 17:00 MESZ

The webinar is free to attend and open to everyone!

Click HERE to register.

Background information:

Excerpt: Real-time interface: deepening

"Since October 2020, grid operators and market participants have been working together on a Real-Time Interface (RTI). The goal of this interface is to enable generators and grid operators to collaborate on increasing and better utilizing transmission capacity and maintaining the electricity grid safely. The RTI specification was published in February 2024."

IEC 61850 Protocol Implementation Document (PID)

Excerpt: "IEC 61850 Real Time Interface (RTI), as defined by the Dutch System Operators specifies the implementation profile of the IEC 61850 Real Time Interface (RTI), as defined by the Dutch System Operators."

30 years after the start of the standardization work for IEC 61850 it is obvious that IEC 61850 is THE standard series when it comes to the exchange of real-time information between power generation sites and control centers of DSOs. 

Italian distribution companies go for IEC 61850 - New!?

I have posted news about the Italian norm CEI 0-16 in 2013 (12 years ago) regarding the use of IEC 61850 for DSO - Distribution System Operators:

Click HERE to see the three old posts.

During the last years I have not seen a lot of discussions regarding Italian DSOs ... maybe I just did not look for it.

By some request today, I searched the internet to see what happened: A LOT ... I guess.

Several up-to-date documents are downloadable for free:

Standards CEI 0-16 and CEI 0-21, TR 57-126 e PAS 57-127

Click HERE for accessing the documents.

One of the key documents is likely: Reference technical rules for the connection of active and passive consumers to the HV and MV electrical networks of distribution Company

<<Standard CEI 0-16 – Versione consolidata di lavoro>>

The document <<Standard CEI TR 57-126>> contains even a SCL File for the IED to be used (guess it is an example; from 2022).

I guess these specifications (for FREE) cover more applications (generation and load) compared to the German FNN Steuerbox (load only; spec for 39 Euro).

Needs further investigation to understand the similarities and differences. Anyway, both use IEC 61850!

After yesterdays post (2025-08-27), I found today (2025-08-28) a nice description of one of the backgrounds for CEI 0-16:

Enabling of frequency control on distributed generation by CEI 0-16 Power Plant Controller: an analysis of the benefits on system’s stability

Click HERE for the 190 page paper ... very helpful