JVL Industri Elektronik A/S - User Manual - Integrated Stepper Motors MIS23x, 34x, 43x 217
10.1 General information about CANopen
10.1.4 CANopen, general information
CANopen is a CAN-based, higher-level protocol. The purpose of CANopen is to give an
understandable and unique behaviour on the CAN network. The CAN network is the
hardware level of the system, and CANopen is the software level. CANopen is based on
the communication profile described in CiA DS-301, and specifies all of the basic com
-
munication mechanisms.
CiA DS-301contains message types on the lowest software level. The DSP-402 CAN-
open standard defines the device profile and the functional behaviour for servo drive
controllers, frequency inverters and stepper motors. The DSP-402 constitutes a higher
software level, and it uses the DS-301 communication, but makes the device independ
-
ent of the manufacturer. Not all JVL functionality is available.
The CANbus with real-time capabilities works in accordance with the ISO11898 stand-
ard. The major performance features and characteristic of the CANopen protocol are
described below:
Message-oriented protocol:
The CANopen protocol does not exchange data by addressing the recipient of the mes-
sage, but rather marks each transmitted message with a message identifier. All nodes in
the network check the identifier when they receive a message to see whether it is rele
-
vant for them. Messages can therefore, be accepted by none, one, several or all partici-
pants.
Prioritisation of messages:
As the identifier in a message also determines its priority for accessing the bus, it is pos-
sible to specify a correspondingly rapid bus access for messages according to their im-
portance. Especially important messages can thus gain access to the bus without a
prolonged wait-time, regardless of the loading on the bus at any instant.
This characteristic means that important messages are transmitted with high priority
even in exceptional situations, thereby ensuring proper functioning of a system even dur
-
ing phases of restricted transmission capacity.
TT1092GB
CAN Node
master
Terminator
CAN network
CAN_H
CAN_L
Terminator
CAN Node
slave
CAN Node
slave
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