IFM Electronic CR0451 - Canopen Support by Codesys

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ifm System Manual ecomatmobile BasicDisplay (CR0451) V01
CAN in the PDM360 CAN POUs to CANopen
CANopen support by CoDeSys
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General information about CANopen with CoDeSys
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CoDeSys is one of the leading systems for programming control systems to the international standard
IEC 61131. To make CoDeSys® more interesting for users many important functions were integrated
in the programming system, among them a configurator for CANopen. This CANopen configurator
enables configuration of CANopen networks (with some restrictions) under CoDeSys.
We no longer use the CoDeSys library for these devices. Although a library must be loaded into the
project, it only serves as a dummy.
The CANopen stack is always on the device (in the runtime system). Memory is only reserved for the
data if required.
CANopen terms and implementation
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According to the CANopen specification there are no masters and slaves in a CAN network. Instead of
this there is an NMT master (NMT = network management), a configuration master, etc. according to
CANopen. It is always assumed that all participants of a CAN network have equal rights.
Implementation assumes that a CAN network serves as periphery of a CoDeSys programmable
controller. As a result of this an ecomatmobile controller or a PDM360 display is called CAN master in
the CAN configurator of CoDeSys. This master is an NMT master and configuration master. Normally
the master ensures that the network is put into operation. The master takes the initiative to start the
individual nodes (= network nodes) known via the configuration. These nodes are called slaves.
To bring the master closer to the status of a CANopen node an object directory was introduced for the
master. The master can also act as an SDO server (SDO = Service Data Object) and not only as SDO
client in the configuration phase of the slaves.
'Addresses' in CANopen
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In CANopen there are different types of addresses (IDs):
 COB ID
The CAN Object Identifier addresses the message (= the CAN object) in the list of devices.
Identical messages have the same COB ID. The COB ID entries in the object directory contain the
CAN identifier (CAN ID) among others.
 CAN ID
The CAN Identifier identifies CAN messages in the complete network. The CAN ID is part of the
COB ID in the object directory.
 Node ID
The Node Identifier identifies the CANopen devices in the complete network. The Node ID is part
of some predefined CAN IDs (lower 7 bits).