Wednesday, March 16, 2011

What is the ACSI?

The ACSI is the "Abstract Communication Service Interface" defined in IEC 61850-7-2.

The ACSI was invented during a meeting of some experts that met here in Europe at the beginning of the project IEC 61850 (between 1995 and 1997). The reason was quite simple: We had TWO proposals for protocol profiles: (1) MMS TCP/IP and Ethernet (2) Profibus FMS. Each solution was supported by some 50 per cent of the members.

What to do now? I was deeply involved in the fieldbus standardization. We had so many fights since the late 80s ... which damaged the reputation of the standardization in the early 90s. I suggested NOT to fight in IEC 61850 but to define an abstract service model that could be mapped to MMS and to FMS. The first was specified in IEC 61850-8-1 and the second in IEC 61850-8-2. Even no official IEC draft has ever been published for IEC 61850-8-2.

Later we had a similar discussion in the project IEC 61400-25-4 in IEC TC 88 (Wind Turbines). We agreed to follow the approach of the abstract model of IEC 61850-7-2, to use the 8-1 MMS mapping, to add mappings for OPC XML DA, IEC 60870-5-101/104 and DNP3, and to define a concrete webservice for each abstract service of the ACSI.

The services of the ACSI and some explanation could be found here:

Click HERE for C/S and P/S
Click HERE for Data Acquisition
Click HERE for Webservices
Click HERE for MMS

By the way, the services in IEC 61850 are very general ... applicable almost everywhere!

My observation is, that (with some exceptions) ALL applications of IEC 61850 apply the MMS mapping ... that does not mean that everybody likes MMS ;-)

Most people using IEC 61850 do not care about MMS - and ALL should not care!

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