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There are a few crucial aspects: (1) MMS as a standard that needs outdated OSI upper layers, (2) MMS is very complex and does not easily fit for IEC 61850-7-2 ACSI ...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).

IEC 61850: Realtime Interface Version 2.0 - Why This Matters

Netbeheer (the Netherlands organization of Distribution System Operator) published the Realtime Interface version 1.0 (RTI 1) in 2024.

The revised specification (named RTI 2) has been developed last year and proposed to IEC TC 57 as an additional solution for communication of IEC 61850 information (New Work Item Proposal IEC 61850-8-3).

The one page list of good reasons for the new solution 

The combination of IEC 61850 data model / services and WebSocket protocol
Why this matters

can be found here.

See also:
https://blog.nettedautomation.com/2025/12/long-awaited-christmas-gift-for-smarter.html

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.