IEC TC 57 WG19 proposes CIM Profiles to JSON schema Mapping

IEC TC 57 WG is discussing the use of JSON for transferring message payload

DRAFT 62361-104:
POWER SYSTEMS MANAGEMENT AND ASSOCIATED INFORMATION
EXCHANGE – INTEROPERABILITY IN THE LONG TERM –

Part 104: CIM Profiles to JSON schema Mapping

The introduction says:

"This standard is one of the IEC 62361 series which define standards that may be used by all
Working Groups within TC57. These standards address areas of interest that impact multiple
standards and provide consistency for implementations.
This part 104 describes a mapping from CIM profiles to IETF JSON schemas and defines the
rules that CIM JSON message payloads must adhere to.
The principle objective of this part 104 is to facilitate the exchange of information in the form of
JSON documents whose semantics are defined by the IEC CIM and whose syntax is defined by
an IETF JSON schema. ..."

JSON is applicable for encoding of CIM (IEC 61968/70) message payload and - as I believe - also for IEC 61850 message payload!

By the way: The post on "IEC 61850-8-2 Versus IEC 61850-8-1" discussing the use of JSON in addition to MMS/ASN.1/BER and MMS/ASN.1/XER has been visited 2,000 times since July 5, 2019 --> or 16 times per day.

Click HERE for additional discussion on the use of JSON ...

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.

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]

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.