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There are a few crucial aspects: (1) MMS as a standard that needs outdated OSI upper layers, (2) MMS is very complex and does not easily fit for IEC 61850-7-2 ACSI ...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

Free ASN.1 Browser for IEC 61850-8-3 ASN.1 Module from RTI2 PoC

If you want to browse easily the ASN.1 message schema for the new project IEC 61850-8-3 (DSM) underway, check out this free browser: 

https://www.nettedautomation.com/editor

A preliminary asn.1 module for IEC 61850-8-3 (from PoC of RTI2) is available for download:

This is how it looks like:

and ...

The schema is very simple compared to MMS for IEC 61850-8-1.

Let us know if you have any question.

Extended Video on IEC 61850-8-3 Available - Example Messages

 An extended version of the video on  

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 

is available. I have added some five minutes ... total time is 23 minutes.

I have added mainly two examples of services for IEC 61850-8-1 (MMS) and IEC 61850-8-3 (DMS):

The figure above shows how a client can get the list of logical nodes from the server with MMS ... and with DMS:

Details can be watched in the video ... enjoy.

IEC 61850 Series for Any Automation Domain using Electric Power (two Examples)

The standard series IEC 61850 is applicable for simple applications and huge systems. The standard is not restricted to a specific domain. Like electric power is everywhere. So could IEC 61850 be everywhere.

I have discussed this briefly in the context of a LinkedIn post.

Now it's time to discuss briefly two simple applications ... just looking at the two models ... without further explanations.

The German FNN Steuerbox

The Steuerbox is mainly providing schedules for the interface between the grid and the power user:

This model is defined for a special use-case: Steuern (remote control). No need for an engineering tool ... it is just a fixed model ...

The Netherlands RTI (Real-Time Interface) for power generation (> 1 MW)

... this is a fixed model with some details:

The RTI models and services are currently using IEC 61850-8-1 (MMS) communication (RTI 1). The RTI 2 will finally use the IEC 61850-8-3 (DMS) once it is specified. A Task Force has started to specify the new standard in May 2026.

The fixed models allow for a high level of interoperability. The central systems (representing the IEC 61850 clients) can communicate with and IED following these specifications. In the case of the FNN Steuerbox it has been proven that the client application could talk to all steuerboxes in the field without paying attention to which vendors device it is talking to.

REAL INTEROPPERABILITY !!

Why is there an Need for an Additional Service Mapping in IEC 61850 (IEC 61850-8-3)?

The two service mappings for IEC 61850 are IEC 61850-8-1 (MMS) and IEC 61850-8-2 (MMS/XML). The mapping IEC 61850-8-1 is in operation from the first days when IEC 61850 was implemented and used ... all over ... in millions of devices and thousands of systems. Ok ... perfect.

Why is there an need for an additional service mapping in IEC 61850 (IEC 61850-8-3)? 

Simply because of the complex and tricky mapping to MMS (Manufacturing Message Specification, ISO 9506). 

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 

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 (updated version 2026-06-04, 23 minutes).

It is likely that this will become a major shift in the use of IEC 61850.

Enjoy!