Tissue Process for IEC 61850-8-2 open for posting Tissues

Please note that the Tissue Database is now open for part IEC 61850-8-2:

Communication networks and systems for power utility automation –
Part 8-2: Specific communication service mapping (SCSM) – Mapping to Extensible Messaging Presence Protocol (XMPP)

http://tissue.iec61850.com/part/52

IEC TC 57 just published FDIS IEC 61850-8-2 (Mapping to XMPP)

IEC TC 57 just published FDIS IEC 61850-8-2 (Mapping to XMPP) - 253 pages !

(57/2020/FDIS)

Voting ends: 2018-08-24

Part 8-2: Specific communication service mapping (SCSM)
– Mapping to Extensible Messaging Presence Protocol (XMPP)

The long wait for a second SCSM is over!

The new mapping of IEC 61850 describes a specific communication service mapping
(SCSM) over the Extensible Messaging and Presence Protocol (XMPP), providing detailed
information on how to create and exchange concrete communication messages that
implement abstract services and models specified in IEC 61850-7-4, IEC 61850-7-3, and
IEC 61850-7-2.

Note that the MMS messages (defined using ASN.1) are used in IEC 61850-8-1 AND -8-2 ! The only crucial difference between the two message and model mappings (in 8-1 and 8-2) is this:

8-1 uses BER (Basic Encoding Rule) for the messages on the wire, while 8-2 uses (XER (XML Encoding Rule). The complexity of the MMS messages is the same in both mappings - because the structure and how to build messages and how to carry the 7-2 services and 7-x models are the same!

The challenges to implement 8-2 message mapping are more or less the same as with 8-1. Note that the messages in XER are far longer than with BER.

There is - of course - a difference between the two: The transport of messages in 8-2 uses XMPP.

Some may argue, that there are more tools available for XER than for BER. Ok.

IEC 61850-8-2 is far away from something simple and easy to implement and use - especially when you need only a few simple services and models.

XMPP, XML, and MMS: Two New TC 57 CDVs available for Public Comments

IEC TC 57 has published the following two CDV documents and allows you access to them:

57/1823/CDV
IEC 61850-8-1/AMD1 ED2: Amendment 1 - Communication networks and systems for power utility automation - Part 8-1: Specific communication service mapping (SCSM) -
Mappings to MMS (ISO 9506-1 and ISO 9506-2) and to ISO/IEC 8802-3

57/1833/CDV
IEC 61850-8-2 ED1: Communication networks and systems for power utility automation - Part 8-2: Specific communication service mapping (SCSM) -
Mapping to Extensible Messaging Presence Protocol (XMPP) 

You can study these two documents and provide comments.

Click HERE for the access (need to register only).

XMPP is used here to transport the XML message payloads between IEC 61850 server and client. The main contents of the messages are MMS messages (defined in ASN.1) and encoded with ASN.1 XER (XML encoding rule) - instead of ASN.1 BER (basic encoding rule). 

Example (excerpt):

Quite interesting. Most of what you have understood of MMS (subset used in IEC 61850-8-1) is applicable for 8-2 as well.

Click HERE for an introduction to ASN.1 and a discussion of why we need encoding rules.

Mapping of IEC 61850-7-x to XMPP: Nice Paper in PACWorld Magazine

The XMPP technology (Extensible Messaging and Presence Protocol) has been selected as the communication solution to address the Smart Grid specific challenges and use cases, which deviate from a typical substation automation use case.

The additional mapping will be published as IEC 61850-8-2.

A nice overview can be found in a paper published recently in the PACWorld magazine:

Click HERE for the full paper.

Note that from a message encoding point of view the MMS-ASN.1-BER messages are mapped directly to ASN.1-XER coded messages. The ASN.1 Tag numbers are mapped to XML Element names. The whole message schema is the same in both mappings.

XMPP - IEC 61850-8-2 Defines Additional Communication Mapping

IEC TC 57 has published a first draft for an additional mapping of IEC 61850 information models and communication messages.

IEC 61850-8-2 (57/1583/CD):
Communication networks and systems for power utility automation - Part 8-2: Specific Communication Service Mapping (SCSM) – Mapping to Extensible Messaging Presence Protocol (XMPP)

Closing date for comments is 2015-09-11

The new mapping defines (relies on) the following definitions:

Service mapping (unchanged)
The abstract (client-server) services of IEC 61850-7-2 are mapped to MMS as defined in the existing IEC 61850-8-1 Ed2.

Message Encoding (new concrete encoding)
The encoding of the messages uses ASN.1 XER (XML encoding rule) – in addition to ASN.1 BER according to IEC 61850-8-1 Ed2. The encoding defines an XML schema – contained in the draft.

Model mapping (unchanged)
As in IEC 61850-8-1 Ed2. This applies to the flattening of the object identification and adding Functional Constraint (FC=ST or MX) in the path name and using “$” for “.”:

Bay5_MMXU1$MX$Hz$mag$i

Underlying Transport (new T-Profile)
The transport (exchange) of the XER encoded messages uses a new approach: using XMPP.

This new transport mechanism and encoding will be used between all kinds of utility Distributed Energy Resource devices and related power management systems, over any communication infrastructure including public networks.

The coming IEC 61850-8-2 can be understood as an (encoding and transport) extension of the existing IEC 61850-8-1.

It is very crucial that most parts of implementations and tools can be re-used! Re-Use is one of the basic approaches used in IEC 61850! Don’t start always from scratch – use what is available and add something.

So, to read the frequency of Bay5 is almost the same .. using the reference
“Bay5_MMXU1$MX$Hz$mag$i”
encoded in ASN.1 BER (IEC 61850-8-1) and in ASN.1 XER (IEC 61850-8-2).

See also example of encoding.

A second document explains the needs and background for an additional mapping:

IEC 61850-80-3 TR (57/1584/DTR):
Communication networks and systems for power utility automation -
Part 80-3: Mapping to Web protocols – Requirements and technical choices

It describes the requirements and the technical principles for a new specific communication service mapping (SCSM) based on Web Protocols.
For more information about the candidate technologies which have been analyzed but not selected as well as about the selection process used for choosing the technology, national committees are invited to consult document 57/1585/INF which is circulated in parallel:

Accompanying document to 57/1584/DTR, Proposed IEC TR 61850-80-3

It mainly describes the technical solutions which have been investigated but finally not selected for the SCSM of the IEC 61850 based on Web Protocols.

1. IEC 61400-25-4 Annex A (Web services)
2. DPWS (Devices Profile for Web Services)
3. REST (Representational State Transfer)
4. XML messaging over Websocket
5. ACSI XML Messaging
6. OPC UA

The finally chosen solution  “MMS XER payload over XMPP as transport” was recognized after several years of work as the preferred solution – especially from a fast time-to-market point of view.

What does XMPP provide?

XMPP (RFC 6120) is a middleware messaging and presence protocol supporting decentralized architectures and provides:

• Registering resources in publicly reachable servers
• Resolving resources based on names
• Security (authentication, integrity, confidentiality) for the communication with the XMPP server

This fits well to the information models defined in IEC 61850.

Draft IEC 61850-8-2 SCSM – Mapping to XER and XMPP

Some 20 years after the first draft IEC 61850-8-2 SCSM (Mapping to Profibus FMS) we could expect the real IEC 61850-8-2 to be available by end of 2015.

The draft 8-2 provides an additional mapping of the messages of MMS by XER (XML Encoding Rule) and XMPP.

The MMS messages for IEC 61850-8-2 (above TCP/TLS/XMPP) are just differently encoded as in IEC 61850-8-1, as can be seen by the following example:

ASN.1 BER uses a binary encoding that produces less overhead compared to XER. But there will be many benefits provided by IEC 61850-8-2.

According to a presentation by Siemens during the Hanover Fair 2015, these are the main conclusions:

1. It provides a secure and powerful communication for public networks considering end-to-middle and end-to-end security relations
2. IEC 61850-8-2 is intended to use for power management and demand response of DER (distributed energy resources)
3. In 2015 the IEC TC57 working group WG17 will finalize and publish this new specification

Click HERE for the full presentation [pdf, 3 MB]

MMS & ASN.1 & XER & XMPP selected as the second SCSM of IEC 61850

The second SCSM for the ACSI Client-Server information exchange service models will be the mapping of the ACSI service models to MMS ASN.1 XER and XMPP. IEC TC 57 just released the 122 page document 57/1497/DC:

Draft IEC 61850-80-3 TR, Communication networks and systems for power utility automation – Part 80-
3: Mapping to web protocols – Requirement analysis and technology assessment

The document mainly lists the crucial needs and why the mapping to “MMS ASN.1 XER and XMPP” has been chosen to be published as IEC 61850-8-2 soon.

Chapter 7 presents the future SCSM 8-2, including an overview of the main selected technology: XMPP.

The following goals have been particularly considered for the definition of this SCSM:

• Identify a single profile supporting all the services required by the domains and defined today in ACSI.
• Cover the full life cycle of a IEC 61850 system, in collaboration with the System Management work in WG10 (from configuration, through conformance testing, down to maintenance). For this purpose, the present document may recommend some changes in other parts of IEC 61850 like part 6, part 10, etc.
• Deploy cyber-security to ensure a secure environment (in conjunction with IEC TC 57 WG 15 work).
• Propose rules for cohabitation with other mappings such as IEC 61850-8-1 and IEC 61850-9-2, and possibly recommend communication profiles depending on specific application context (pole-top equipment, inside DER, connection of DER, …).

Check with your national IEC TC 57 mirror committee for a copy of the above mentioned document.

Congratulation for the tremendous success of the web service mapping team!!! Great work!

That means: IEC 61850 will be the preferred solution in substations and many applications outside!!

Web Services for IEC 61850: MMS/XER over XMPP?

Some 18 months ago I have reported on a standardization project within IEC TC 57 defining web services as a second SCSM (Specific Communication Service Mapping) for IEC 61850. In the meantime it seems very likely that a mapping to XMPP (Extensible Messaging and Presence Protocol) will be used as the only mapping in the future IEC 61850-8-2.

The secretary of IEC TC 57 has presented a slide (slide 5) with the following requirements during a public event at the Hannover Messe 2014:

• “Part 8-2 Specific communication service mapping (SCSM) – Mappings to web protocols
• Comply with the new edition of IEC 61850-7-1, IEC 61850-7-2, IEC 61850-7-3, and IEC 61850-7-4
• Support the existing application data model defined in IEC 61850-7-410, 7-420 and 61400-25-2
• Identify which web services specification should be considered to deploy cyber-security, in conjunction with IEC TC 57 WG 15 work
• complementary to the existing SCSM (8-1), not competing”

He reported on the status of work: “Konsens bei XMPP als Lösung” (consensus to apply XMPP as solution).

Click HERE for the complete presentation of the secretary of IEC TC 57 during the Hannover Messe 2014 [German, pdf]

MMS messages encoded in XML (XER – XML Encoding Rules for ASN.1, ISO 8825-4) may be used as payload of the XMPP messages.

What would that mean for IEC 61850-8-1 (MMS ASN.1 BER encoded messaging) implementations? First: the 8-1 solutions would continue to be used. Second: an additional ASN.1 encoding rule would add some software at the encoding layer … and finally the addition of the “transport or middle layer” XMMP would offer a new “transport mechanism”. That’s it.

This way most of the IEC 61850 related software (API, datasets, reporting, logging, control, system configuration language, modeling and models, …) would be used unchanged!

By the way, using ASN.1 XER in addition to BER has been proposed and discussed some 20 years ago within ISO TC 184 SC5 WG2. It was too early.

Since MMS is independent of encoding, there seems to be no (technical) question to using XER.