Manufacturing Message Specification (MMS) is an international standard (ISO 9506) dealing with messaging systems for transferring real time processdata and supervisory control information between networked devices or computer applications. The standard is developed and maintained by the ISO Technical Committee 184 (TC184). MMS defines the following

• A set ofstandard objects which must exist in every device, on which operations like read, write, event signaling etc. can be executed.Virtual manufacturing device (VMD) is the main object and all other objects like variables, domains, journals, files etc. comes under VMD.
• A set ofstandard messages exchanged between a client and a server stations for the purpose of monitoring or controlling these objects.
• A set ofencoding rules for mapping these messages to bits and bytes when transmitted.

MMS was standardized in 1990 under two separate standards as

1. ISO/IEC 9506-1 (2003): Industrial Automation systems - Manufacturing Message Specification - Part 1: Service Definition
2. ISO/IEC 9506-2 (2003): Industrial Automation systems - Manufacturing Message Specification - Part 2: Protocol Specification

This version of MMS used seven layers ofOSI network protocols as its communication stack:

Because theOpen Systems Interconnection protocols are challenging to implement, the original MMS stack never became popular. In 1999, Boeing created a new version of MMS usingInternet protocols instead of the bottom four layers of the original stack plus RFC 1006 ("ISO Transport overTCP") in the transport layer. The top three layers use the same OSI protocols as before.

In terms of the seven-layerOSI model, the new MMS stack looks like this:

With the new stack, MMS has become a globally accepted standard.^{[citation needed]}

• MMS Protocol Details
• MMS Overview
• MMS V1 Abstract Syntax
• MMS Protocol Description
• MMS. Presentation by Prof. Dr. H. Kirrmann, ABB Research Center, Baden, Switzerland

• ISO standards

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