The M-Bus: A Documentation Rev. 4.8

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Table of Contents

Remarks on this online documentation

1 Introduction

2 The Basics of Serial Bus Systems

2.1 Applications and Definitions

2.2 Basic Functions of Bus Systems

2.2.1 Access Techniques

2.2.2 Synchronization of Participants

2.2.3 Error Processing

2.3 The OSI Reference Model

3 Overview of the M-Bus

3.1 Requirements of a Bus System for Consumer Utility Meters

3.2 The M-Bus in the OSI Model

4 Physical Layer

4.1 Principles of Operation

4.2 Specifications for Bus Installations

4.3 Specifications of the Repeaters

4.4 Slave Design

5 Data Link Layer

5.1 Transmission Parameters

5.2 Telegram Format

5.3 Meaning of the Fields

5.4 Communication Process

5.5 FCB- and FCV-Bits and Addressing

5.5.1 Applications of the FCB-mechanism

5.5.2 Implementation aspects for primary addressing

6 Application Layer

6.1 CI-Field

6.2 Fixed Data Structure

6.3 Variable Data Structure

6.3.1 Fixed Data Header

6.3.2 Variable Data Blocks

6.3.3 Manufacturer Specific Data Block

6.4 Configuring Slaves

6.4.1 Switching Baudrate

6.4.2 Writing Data to a Slave

6.4.3 Configuring Data Output

6.5 Generalized Object Layer

6.6 Application Layer Status

6.7 Special Slave Features

6.7.1 Auto Speed Detect

6.7.2 Slave Collision Detect

6.7.3 Use of the Fabrication Number

6.7.4 Hex-Codes $A-$F in BCD-Data Fields

7 Network Layer

7.1 Selection and Secondary Addressing

7.3 FCB-Bit and Selection

7.4 Searching for Installed Slaves

7.4 Generalized Selection Procedure

8 Appendix

8.1 Alarm Protocol

8.2 Coding of Data Records

8.3 Tables for Fixed Data Structure

8.3.1 Measured Medium Fixed Structure

8.3.2 Table of Physical Units

8.4 Tables for Variable Data Structure

8.4.1 Measured Medium Variable Structure

8.4.2 Data Field Codes

8.4.3 Codes for Value Information Field (VIF)

8.4.4 Extension of primary VIF-Codes

8.4.5 Codes for Value Information Field Extension (VIFE)

8.5 References

Remarks on this online documentation:
The HTML layout of this document is far from perfect. The intention was to produce a readable output in a short time. It was done using the Winword HTML converter with very few manual changes.
It is recommended to download the Winword version, if you use this document more than once.
F. Miehlisch, may 1998
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