Functionality Of Cbc With Canopen - Siemens 6RA7086-6KS22 Operating Instructions Manual

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Similar to other field bus systems, CANopen employs two basic data transmission mechanisms:
The rapid exchange of short process data via so-called "process data objects" (PDOs) and the
accessing of entries in the object directory via so-called "service data objects" (SDOs). Process
data objects are generally transferred either event-oriented, cyclically or on request as broadcast
objects without an additional protocol overhead. SDOs are used mainly to transmit parameters
during the device configuring process and generally for the transmission of longer data areas.
A total of 8 bytes of data can be transferred in a PDO. The assignment between application objects
and a PDO (transfer object) can be set by means of a structure definition ("PDO mapping") stored
in the OD and is thus adaptable to the individual operating requirements of a device.
SDOs are transmitted as a confirmed data transfer with two CAN objects in each case between
two network nodes. The relevant object directory entry is addressed through the specification of
index and subindex. Messages of unrestricted length can be transferred in principle. The
transmission of SDO messages involves an additional overhead.
Standardized, event-oriented, high priority alarm messages ("Emergency Messages") are
available for signaling device malfunctions.
The functionality required for the preparation and coordinated starting of a distributed automation
system corresponds to the mechanisms defined under CAL Network Management (NMT); this also
applies to the "Node Guarding" principle underpinning the cyclical node monitoring function.
Identifiers can be entered directly into the data structures of the object directory to assign CAN
message identifiers to PDOs and SDOs; predefined identifiers can be used for simple system
structures.

7.7.3.2.2 Functionality of CBC with CANopen

The CBC with CANopen supports only minimal boot-up as defined in communication profile CiaA
DS-301 (Application Layer and Communication Profile).
Up to four Receive PDOs and four Transmit PDOs are available. Parameters U711 to U714 can be
programmed to select the mapping and communication properties of the Receive PDOs and
parameters U715 to U718 to set the mapping and communication properties of the Transmit
PDOs.
Dynamic mapping, i.e. changing the assignment between the objects from the object directory
and a PDO in operation, is not supported by the CBC. Transmission type and identifier of the
communication objects (PDO, SDO, SYNC, EMCY and Node Guarding Object) can, however, be
set via SDOs in operation. These settings override the settings of the CP parameters and are
erased when the supply voltage is switched off.
One server SDO is available.
Another available communication object is the SYNC object. Using a synchronization message,
the CAN master can synchronize the transmission and reception of PDOs for the whole network
("synchronous PDOs").
The EMCY object (Emergency Object) is implemented. This telegram is used to signal all faults
and alarms generated in the SIMOREG system via the CAN Bus.
The network functionality is monitored via the Node Guarding Telegram with which the master
addresses the slaves cyclically. Each slave must individually respond to this telegram within a
parameterizable time frame.
If the master does not receive a response to its request, the communication link to the slave must
be malfunctioning in some way (e.g. cable break, bus connector removed, etc.).
If the slave does not receive a Node Guarding Telegram from the master within a particular time
period (Life Time Event), it can assume that there is error in the communication link. The reaction
of the slave to this event can be parameterized in parameter U719.
Canopen modes Velocity Mode (speed control) and Profile Torque Mode (torque control), both in
accordance with CiA DS-401 (Device Profile for Drives and Motion Control), and the manufacturer-
specific Current Mode (current control) are implemented.
SIEMENS AG 6RX1700-0AD76
SIMOREG DC Master Operating Instructions
Start-Up
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