User guide

9 System bus "CAN on board"
9.4 Structure of the CAN data telegram
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Lenze · 8400 BaseLine C · Reference manual · DMS 1.6 EN · 01/2014 · TD05
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9.4.2 User data
All nodes communicate by exchanging data telegrams via the system bus. The user data area of the
CAN telegram either contains network management data or parameter data or process data:
Networkmanagement data
(NMT data)
• Control information on start, stop, reset, etc. of communication to specific nodes or to all nodes
of the CAN network.
Process data
(PDOs – process data objects)
• Process data are transferred via the process data channel.
• Process data can be used to control the controller.
• Process data are not
saved to the controller.
• Process data are transmitted between host system and nodes to ensure continuous exchange
of current input and output data.
• Process data usually are unscaled/scalable raw data.
• Process data are, for instance, setpoints and actual values.
• The exact meaning of the PDO file contents is determined via the function block editor (FB Edi-
tor) in the I/O level or via the PDO mapping.
Parameter data
(SDOs – service data objects)
• Parameter data are the CANopen indexes or, in case of Lenze devices, the codes.
• Parameters are, for instance, used for one-off plant setting during commissioning or when the
material is changed on a production machine.
• Parameter data are transmitted as SDOs via the parameter data channel. They are acknow-
ledged by the receiver, i.e. the transmitter gets a feedback about the transmission being suc-
cessful or not.
• The parameter data channel enables access to all Lenze codes and CANopen indexes.
• Parameter changes are automatically saved to the controller until mains switching.
• In general, the parameter transfer is not time-critical.
• Parameter data are, for instance, operating parameters, diagnostic information and motor data
as well as control information on the interconnection of function blocks in the I/O level of the
FB Editor.