Key terms

Term	Definition
C-Field	The control or function field of the telegram. It provides information about the telegram, such as the 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.
VIF / VIFE	Value information field and value information field extension. The VIF and VIFE contain information 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.