Schneider Electric Understanding the M-Bus Protocol and Its Implementation

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

Related topics

•See the M-Bus organization website at www.m-bus.com for more information on the M-bus protocol.

•See “Hardware overview” on page 16 for the location of the communications LED.

•See “Communications setup” on page 84 for information on setting the baud rate using a telegram.

M-Bus protocol support

The meter supports the M-Bus protocol as follows:

•Mode 1 communications (least significant bit first).

•Telegram formats:

—Single character

—Short frame

—Long frame

•Function codes (C-field bits 3-0):

—SND_NKE: Initiates of communications between the master and slave.

—SND_UD: The master sends user data to the slave.

—REQ_UD2: The master requests Class 2 user data from the slave.

—RSP_UD: The slave sends requested data to the master.

•Secondary addressing in accordance with the M-Bus standard.

•Broadcast telegrams.

Related topics

•See the M-Bus organization website at www.m-bus.com for more information on the M-Bus protocol, including secondary addressing procedures.

•See “Fixed data header” on page 77 for the meter-specific information required for secondary addressing (for example, identification number, manufacturer and medium).

M-Bus protocol implementation

M-Bus tool for viewing data and configuring the meter

The M-Bus tool provides a graphical user interface where you can view meter data and configure meter settings. To obtain the tool, go to www.schneider-electric.com and search for your meter model then select Downloads or contact your local Schneider Electric representative.

Communications LED indicator for M-Bus meters

The communications LED indicates the status of the communications between the meter and the network as follows:

LED state	Description
The LED is flashing	Communication with the meter has been established.
	NOTE: The LED flashes even if there is a communications error.
The LED is off	There is no active communication.

Related topics

•See “Hardware overview” on page 16 for the location of the communications LED.

•See “M-Bus tool for data display and meter configuration” on page 85 for information on obtaining and using the M-Bus tool.

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