Schneider Electric Mastering M-Bus Communications for Indoor Furnishings Devices

iEM3100 / iEM3200 / iEM3300 series user manual Communications via M-Bus

Chapter 7 Communications via M-Bus

What is in this chapter?

This chapter contains the following sections:

M-Bus communications overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 M-Bus protocol support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 M-Bus protocol implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Variable data structure telegram information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Telegram information for data records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Telegram information for meter configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 M-Bus tool for data display and meter configuration . . . . . . . . . . . . . . . . . . . . . . . . . 85

M-Bus communications overview

M-Bus is a master / slave communications protocol where the master initiates transactions and the slave(s) respond with the requested information or action. Data is transferred using hexadecimal telegrams.

Communications via M-Bus protocol is available on the iEM3135, iEM3235 and iEM3335.

The information in this section is intended for users with an advanced understanding of M-Bus protocol, their communications network and their power system.

Configuring basic communications settings

Before communicating with the meter via M-Bus protocol, use the HMI to configure the following settings:

Setting	Possible values
	300
	600
Baud rate	1200
	2400
	4800
	9600
Primary address	1–250

Key terms

Term	Definition
	The control or function field of the telegram. It provides information about the telegram, such as the
C-Field	direction of data flow (master to slave or slave to master), the status of the data flow and the
	function of the message.
CI-Field	The control information field of the telegram. It defines the type and sequence of data to be
	transmitted.
Fixed data header	Contains device and manufacturer identification information.
DIF	Data information field. The DIF contains information about the function of the data (for example,
	instantaneous versus maximum) and the data format (for example, 16-bit integer).
DIFE	Data information field extension. A DIFE contain additional information about the data, such as tariff
	and subunit.
Master	A device that issues commands and receives responses from slave devices. There can be only one
	master per serial network.
Slave	A device that provides information or performs actions in response to requests from the master.
	Value information field and value information field extension. The VIF and VIFE contain information
VIF / VIFE	about the value (for example, whether it is an energy or power value).
	The meter uses both primary VIFE (as detailed in the M-Bus protocol documentation) and
	manufacturer-specific VIFE.

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