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Application Report No. 200.4.3
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Comparing CANopen and the Lenze system bus CAN
and static PDO mapping in EDS files
CANopen fieldbus
all
all
all
Index
1.
STRUCTURE OF A CANOPEN SYSTEM..................................................................................2
2.
CANOPEN PROFILES ...............................................................................................................3
3.
STATES OF A CANOPEN NETWORK ......................................................................................5
4.
LENZE SYSTEM BUS CAN .......................................................................................................6
4.1.
4.2.
4.3.
5.
EDS DEVICE DESCRIPTION FILES..........................................................................................8
5.1.
6.
1. MAPPING INDICES ............................................................................................................12
2. MAPPING THE PROCESS DATA TO THE PDOS ....................................................................12
CANOPEN CONFIGURATION.................................................................................................14
8.1.
8.2.
9.
OBJECTIVE: PDO MAPPING....................................................................................................9
ADAPTED EDS FILES .............................................................................................................12
7.1.
7.2.
8.
STRUCTURE OF AN EDS FILE .................................................................................................8
WHAT IS PDO MAPPING? ........................................................................................................9
6.1.
7.
MAIN DIFFERENCES BETWEEN CANOPEN AND THE LENZE SYSTEM BUS CAN...........................7
ADVANTAGES OF THE LENZE SYSTEM BUS CAN......................................................................8
ADVANTAGES OF CANOPEN ..................................................................................................8
SYCON TOGETHER WITH THE EDS FILE "82MVV100.EDS"....................................................15
SYCON TOGETHER WITH AN ADAPTED EDS FILE ...................................................................19
APPENDIX ................................................................................................................................22
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1. Structure of a CANopen system
A CANopen system consists of a CANopen master and some CANopen slaves. This
architecture is also called a single-master system, since the master is responsible for the
whole bus communication. This means that data is only exchanged between the master
and the individual slaves. In addition, the CANopen master exchanges data with a PLC.
The PLC can be a software or a hardware PLC. Hardware PLCs are stand-alone
components, e.g. the Siemens Simatic S7-300 and 400. Software PLCs are plug-in cards
for PCs and industrial PCs.
PC
Higher-level
PLC
CANopen
master
RS 232 / CAN
CANopen
slave 1
CANopen
slave 2
Configuration
software
CANopen
master
CANopen
slave n
CANopen
slave 3
…………..
Process data communication (PDOs) between
master and slave
Parameter communication (SDOs) between master
and slave
Figure 1: Schematic structure of a CANopen system
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EDS
file
Application Report No. 200.4.3
ACP
2. CANopen profiles
As in every fieldbus, CANopen also has a number of profiles which are created and
extended by the users' and manufacturers' organisation CiA (CAN in Automation). The
features and functions of the profiles are described in specifications. Figure 2 offers a
schematic overview of the most important profiles.
Application program
Device
profile
(DS 4XX)
Interface Application
profile
profile
(DS 4XX) (DS 4XX)
“Manager”
profile
(DS 302)
Manu
facturerspecific
profile
Frameworks (e.g. DS 302, DS 304, DS 307)
Communication Profile (DS 301)
Application Layer (DS 301)
Layer
setting
services:
baud rate
and
Data link layer and high-speed transceiver (ISO 11898-1/-2)
node ID
(DS
305)
Bit-timing and connector pin-assignment (DS 301, DR 303)
Figure 2: Overview of CANopen profiles
The specifications DS 301, DR 303 and ISO 11898-1/-2 mainly describe physical bus
features with which every CAN node must comply. Higher than these is the DS 301
specification. This specification is the basic specification for all other application profiles.
The most important features of the DS 301 specification are:
·
·
·
general communication features such as node identifiers, Sync message
management and the monitoring functions Node Guarding / Heartbeat
SDO management (service data objects, parameter communication), the number
of parameter channels, the channel identifiers, activating and deactivating the
channels
PDO management (process data objects, process data communication), the
number of process data channels, the channel identifiers, activating and
deactivating the channels
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The DS 4xx profiles always require the DS 301 profile as a basis. They are application
profiles which means that they are assigned to certain kinds of nodes, e.g. DS 401 is
assigned to CAN I/O systems, DS 402 to controllers, etc.
Figure 3 shows the most important application profiles. Please note that the DSP-402
profile was especially created for controllers and Motion Control applications.
Our Lenze CANopen communication modules (EMF 2175 and E82ZAFUC (in
preparation)) support the DS-301 profile, but not the DSP-402 profile.
Figure 3: Overview of the most important application profiles
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3. States of a CANopen network
In a CANopen system, two states can be distinguished.
1. Pre-Operational
After mains connection, all nodes start to initialise, then keep to the state
"Pre-Operational“. In this state, there is only parameter communication (SDOs). Process
data communication is not possible, i.e. PDO messages are ignored by the nodes. This
state is only used for parameter setting. In this state, the CANopen master parameterises
each slave. A CANopen slave can be parameterised using CANopen indices (codes). The
indices are defined in detail in the CANopen specifications and are between 1000hex and
1999hex for the DS 301 profile. Having parameterised the slaves, the CANopen master
uses a special CAN message to switch all slaves or individual slaves to the state
"Operational“. This message is a network management message (NMT message).
2. Operational
In this state, parameter communication (SDOs) as well as process data communication
(PDOs) are possible. If necessary, you can switch between the different states using NMT
messages.
This shows that in a CANopen system, all parameters for bus communication are
managed using the master. In the configuration phase of the system, only the CANopen
master has to be set. In this phase, the slaves are parameterised as well. This applies to
single-master systems in general.
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4. Lenze system bus CAN
The Lenze system bus CAN supports parts of the DS 301 specification. Depending on the
Lenze system bus components used, it has two SDO channels and 1 to 3 PDO channels.
But the Lenze system bus partly differs from typical CANopen networks. It was developed
to enable a communication between different Lenze components.
This system does not need a CANopen master.
Lenze
system bus
CAN
node 1
Lenze
system bus
CAN
node 2
Lenze
system bus
CAN
node 3
…………..
Lenze
system bus
CAN
node n
Drive PLC
Process data communication (PDO) between slave
and slave
Parameter communication (SDO) between slave
and slave
Figure 4. Lenze system bus CAN
When comparing figures 1 and 4, you can see the main difference between a CANopen
system bus and a Lenze system bus. The Lenze system bus allows different CAN nodes
to communicate with each other. This is also possible in CANopen systems, but a lot of
configurations are needed, since the basic configuration is not intended for this purpose.
The technology referred to is known as cross communication and does not need a higherlevel fieldbus master. Each system bus node is allowed to transmit messages via the bus.
Since no higher-level master is required for the Lenze system bus, each slave has to be
configured / parameterised on its own using Lenze codes, which are preferably in the
range of L0350 to L0399.
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Application Report No. 200.4.3
4.1.
ACP
Main differences between CANopen and the Lenze system bus CAN
The features of a CAN slave are provided by a microcontroller (CAN controller). A CAN
controller fulfills different tasks. On the one hand, it must provide the physical bus
features, on the other hand it must process the signals in a software. The physical bus
features are the same for CANopen and the Lenze system bus, since the same hardware
(CAN controller) as in other CANopen nodes is used. They only differ in their software,
since every manufacturer programs the controller with another application software. In
this application software, you can also find the individual CANopen indices and
functionalities.
The Lenze system bus CAN does not support all CANopen functionalities according to
DS 301, since it can operate without a master. SDO and PDO communication is the same
for both systems. In the PDO communication of the Lenze system bus, the identifiers
according to general addressing differ from CANopen. The identifiers for the system bus
can be configured in the same way as in CANopen using selective addressing.
Functions according to DS 301 such as
· Node Guarding
· Heartbeat
· Boot-up messages
· Emergency messages
· dynamic PDO mapping
are not supported by the Lenze system bus.
The NMT message to transit from the state "Pre-Operational“ to "Operational“ can be
generated by setting the Lenze code C0352 to master. After connecting the Lenze node,
which was set as the master in C0352, to the mains, the NMT message is transmitted to
the CAN bus after the boot-up time set in C0356/1.
In general, Lenze nodes can be used in a CANopen network if reading and writing
CANopen indices can be switched off for the CANopen master.
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Application Report No. 200.4.3
4.2.
·
·
·
·
4.3.
·
·
·
ACP
Advantages of the Lenze system bus CAN
The Lenze system bus CAN is easier to parameterise, since you do not need to
know CANopen.
In CANopen, Sync settings, the transmitting and receiving behaviour of the PDO
messages, the identifiers, the number of SDO and PDO messages, etc. must be
set using CANopen indices. For this, good knowledge of CANopen is required.
You do not need a CANopen master.
Cross communication between Lenze nodes is possible.
Advantages of CANopen
The customer does not need to know anything special about CAN when using
nodes from different CANopen manufacturers.
Only the CANopen master must be configured / parameterised, no other settings
are required for the slaves.
After each mains connection, the CANopen master parameterises all nodes
(automatic parameter setting when components are exchanged).
5. EDS device description files
The functions of DS 301 are stored in the indices (codes) of each CANopen node. The
bus can be scanned using the CANopen master configuration software. By reading the
indices, the software can determine the functions supported by each CAN node. You can
find the same information in the device description files of the CAN nodes. These are
called EDS files (electronic data sheets). They are used to configure the CAN offline. The
EDS files are supplied with each CAN node usually in the form of a floppy disk and can be
imported into the configuration software. Their file extension is xxx.eds. In order to
generate EDS files, there are special EDS editors (e.g. CANeds of the company vectorinformatik). EDS test programs are also available, e.g. CANchkeds of the company
vector-informatik. EDS files can be read and processed by every text program, e.g.
Winword or Wordpad.
5.1.
Structure of an EDS file
An EDS file mainly consists of three parts.
Header:
Here you find general information such as the creation date,
the company, the product designation, etc.
Indices:
A description of the CANopen functionalities of the indices
and to what extent they are supported (1000hex – 1999hex).
Mapping indices:
Possible PDO mapping objects (this will be described later on)
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6. What is PDO mapping?
The problem which most often occurs when using CANopen systems and CAN systems
such as the Lenze system bus concerns PDO mapping. This is a CANopen functionality
which is described in the DS-301 profile.
In general, all CANopen profiles consist of functions which must be supported and
functions which can be supported. PDO mapping is an optional functionality in the DS-301
profile.
PDO mapping is not supported by any of the Lenze system bus components.
This fact becomes a problem when using the configuration software tools of the CANopen
master, since these usually require the PDO mapping of the slaves.
PDO mapping means that the data of a CAN slave is mapped to the PDOs. The
CANopen master also assigns the data to certain positions in a PDO message. In order to
do this, the master has to know which data each slave has. The available data is listed in
the EDS file. With the help of this information, data can be mapped to the PDO messages
in the configuration software. When the CANopen system is started, this data assignment
is transmitted to the slaves such that the latter place the right data at the right position in
the PDO message. This functionality is called dynamic PDO mapping, since mapping
PDO messages can be changed at any time.
PDO mapping can also be static which means that it is configured in the EDS file and
cannot be changed by the configuration software of the master.
6.1.
Objective: PDO mapping
1. The whole process data communication between master and slave can be
configured using the master configuration software.
2. The individual CAN PDOs are automatically created by mapping.
3. The sum of process data is known from the mapping process, so the master can
create a memory location equivalent to the sum. This memory location is important
for the data exchange between the master and the PLC connected to it.
Figure 5 shows a schematic overview of dynamic PDO mapping.
It describes the sequence of PDO mapping with the aid of a Transmit-PDO.
Figure 5 shows the example of a CAN slave transmitting a PDO message to the master.
In this PDO message, the status word and CAN OUT1-W1 to 3 are to be mapped.
You will find a figure with a Receive-PDO in the appendix of this Application Report.
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ACP
Application Report No. 200.4.3
Shared
memory
8
SDO messages 1 to 4 for configuring PDO mapping
9
PLC
CANopen
master
Task
3
23h 1Ah 00h 01h mapped index 5DA7 /1
:
:
:
1
Task
CAN slave
4
2
23h 1Ah 00h 04h mapped index 5DA7 /4
Status word
5
CAN-OUT1-W1
6
CAN-OUT1-W2
Status word
CAN-OUT1.W3
7
CAN OUT1 CAN OUT1
.W1
.W2
CAN OUT1
.W3
PDO message with 4 words user data
Figure 5: Schematic overview of dynamic PDO mapping
200.4.3_V1.0_PDO_EDS
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Status word
CAN OUT1 CAN OUT1 CAN-OUT1
.W2
.W1
.W3
Input data:
Index 5CA7 / 1 = control word
Index 5CA7 / 2 = CAN.IN1.W1
Index 5CA7 / 3 = CAN-IN1.W2
Index 5CA7 / 4 = CAN-IN1.W3
:
:
Output data:
Index 5DA7 /1 = status word
Index 5DA7 /2 = CAN-OUT1.W1
Index 5DA7 /3 = CAN-OUT1.W2
Index 5DA7 /4 = CAN-OUT1.W3
:
:
Existing process data of the
slave
Application Report No. 200.4.3
ACP
In the following, the single steps from figure 5 will be explained.
Step 1: CANopen master configuration software
The slave is integrated into the configuration software and physically exists. The CANopen
master knows from the EDS file which process data the slave has. This can now be mapped
accordingly. Some software tools provide a graphical user interface for mapping.
Step 2: SDO message for configuring PDO mapping
During the initialisation phase of the bus, the mapping configured in the software must be
transmitted to the slave via SDO communication. For this purpose, the slave has mapping
indices for each Transmit-PDO and Receive-PDO.
I-1600h =>I-16xxh
I-1A00h => I-1Axxh
Receive-PDO mapping (slave)
Transmit-PDO mapping (slave)
Step 3: Process data existing in the slave
The table shows the process data available for mapping. Either input or output variables can
be process data. The process data which can be mapped is also available in the EDS file.
Steps 4 / 5 : PDO mapping at the slave
The arriving SDO messages map the Transmit-PDO with the process data from the mapping
table.
Step 6: Transmit-PDO
The slave can now transmit the Transmit-PDO containing the mapped process data.
Steps 7 / 8: Process data in the CANopen master
The master stores the arriving process data in the shared memory. Not only the master, but
also the PLC can access the shared memory. The memory enables a data exchange
between the master and the PLC. It is bidirectional which means that the PLC also transmits
new process data, the control word and the setpoint speed from the PLC program to the
master. The master then transmits the data to the bus.
Step 9: Process data and PLC
Process data is processed in the PLC program. The PLC program evaluates and processes
process data from the slaves as well as generates new process data for them.
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7. Adapted EDS files
The EDS files can be adapted to PDO mapping, i.e. process data for the PDOs is statically
mapped in the EDS file.
This requires some modifications in the file.
You will find these modifications in the attached EDS file "E82ZAFCC static PDO mapping".
7.1.
1. Mapping indices
The mapping indices are always at the end of an EDS file.
Example:
_________________________________________________________________________
[5CA7sub1]
ParameterName=CAN-IN1.W1
ObjectType=0x7
DataType=0x0003
AccessType=wo
PDOMapping=1
mapping index
process data name
data type
access rights to the index write only
PDO mapping active value "1“
_________________________________________________________________________
The entry for PDO mapping is usually "0" for Lenze EDS files, since PDO mapping is not
supported.
Four mapping indices are required for each PDO message (4 x 1 word).
7.2.
2. Mapping the process data to the PDOs
The PDO mapping of the individual PDO messages is in the indices.
I-1600 Receive PDO1
I-1601 Receive PDO2
etc.
I-1A00 Transmit PDO1
I- 1A01 Transmit PDO2
etc.
All indices have 4 subindices for the mapping indices.
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ACP
Application Report No. 200.4.3
Example taken from the EDS file Index I-1600 for the 1st Receive-PDO
_________________________________________________________________________
[1600sub0]
ParameterName=Number of Entries not relevant, only indicates the number
of existing subindices
ObjectType=0x7
DataType=0x0005
AccessType=ro
DefaultValue=4
PDOMapping=0
[1600sub1]
ParameterName=PDO Mapping 1
ObjectType=0x7
DataType=0x0007
AccessType=rw
DefaultValue=0x5CA70110
PDOMapping=0
ObjFlags=3
first word in the PDO
access rights to the index read write
mapping index I-5CA7 subindex 1,
1 word data
dynamic mapping OFF
special flag, value=3 such that the mapping
cannot be changed
[1600sub2]
ParameterName=PDO Mapping 2
ObjectType=0x7
DataType=0x0007
AccessType=rw
DefaultValue=0x5CA70210
PDOMapping=0
ObjFlags=3
[1600sub3]
ParameterName=PDO Mapping 3
ObjectType=0x7
DataType=0x0007
AccessType=rw
DefaultValue=0x5CA70310
PDOMapping=0
ObjFlags=3
[1600sub4]
ParameterName=PDO Mapping 4
ObjectType=0x7
DataType=0x0007
AccessType=rw
DefaultValue=0x5CA70410
PDOMapping=0
ObjFlags=3
_________________________________________________________________________
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With the help of these entries, 4 words are mapped to the 1st Receive-PDO of the slave.
The configurations are shown in the configuration software of the CANopen master, i.e. a
memory location is created for 4 words.
The configurations do not apply to all configuration software tools, since these also differ
from each other. Good experiences have been made so far with the configuration software
SyCon of the company hilscher.
8. CANopen configuration
As already described above, a CANopen system is totally configured and parameterised
using the configuration software of the CANopen master.
In the following, we will give further details about the CANopen configuration software SyCon
of the company hilscher.
An offline CANopen network is first configured using the normal EDS file "82MVV100.eds"
and then the adapted EDS file "E82ZAFCC.eds".
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Application Report No. 200.4.3
8.1.
ACP
SyCon together with the EDS file "82MVV100.eds"
First, we will show how to implement a Lenze system bus CAN node if the EDS file has not
been changed.
The figure shows the user interface of the software. A hilscher PC card is used as the
CANopen master. You can now add other CAN slaves to the bus line.
In order to add a new node to the bus line, an EDS file must be chosen. In this case, the
standard EDS file "82MVV100.eds" has been chosen.
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A CAN slave called "8200motec/vector inverter" was added.
When you select "node configuration" in the context menu of the CAN slave, the following
figure is shown.
In this dialogue, you can select some of the features of the CAN slave such as the node
address, node boot up, Node Guarding, etc. You can also configure PDO messages in this
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Application Report No. 200.4.3
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dialogue. In order to do this, you must create Transmit-PDOs and Receive-PDOs. We will
create a new Transmit-PDO.
The PDO identifier and the corresponding CANopen index are shown. Furthermore, you can
give the PDO a name (Transmit-PDO 1).
The data will be accepted if you click on the OK button.
The PDO message was properly created, but no memory location (I/O) has been created for
the data exchange between the PLC and the CANopen master.
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The process data of the PDO can be configured by double clicking.
The table above shows the objects from the EDS file which can be mapped. The table below
shows the predefined mapped objects (static mapping from the EDS file). In this case, there
are no objects available. No process data is mapped, thus no memory location is created.
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Application Report No. 200.4.3
8.2.
ACP
SyCon together with an adapted EDS file
As a comparison, the adapted EDS file "E82ZAFCC" with implemented static PDO mapping
will be added.
A CAN slave called "E82ZAFCC system bus Can 8200vector/motec" was selected. When
you select "node configuration" in the context menu of the CAN slave, the following figure is
shown.
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You may well note that 4 predefined PDOs (Indices 1400, 1401, 1800 and 1801) are already
available in this EDS file.
Next, we will create all 4 PDOs in the software. You can create a PDO in the table below by
double clicking on each predefined PDO.
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Application Report No. 200.4.3
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Note that each of the 4 PDOs created occupies 8 bytes of memory location.
You can open the window with the PDO features by double clicking on the PDO created.
The table above contains the objects from the EDS file which can be mapped. The table
below shows the static mapping from the EDS file, in this PDO e.g. the process data words
CAN-In1.W1 to W4. Due to static PDO mapping, 8 bytes (4 words) of memory location are
created for each PDO.
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Application Report No. 200.4.3
9. Appendix
Shared
memory
8
SDO messages 1 to 4 for configuring PDO mapping
9
CAN slave
Control word
PLC
CAN-IN1.W1
CAN-IN1.W2
Task
4
:
:
:
1
CAN-IN1.W3
3
23h 16h 00h 01h mapped index 5CA7 /1
CANopen
master
2
23h 16h 00h 04h mapped index 5CA7 /4
Output data:
Index 5DA7 /1 = status word
Index 5DA7 /2 = CAN-OUT1.W1
Index 5DA7 /3 = CAN-OUT1.W2
Index 5DA7 /4 = CAN-OUT1.W3
:
:
Task
5
6
Control word
CAN IN1
.W1
CAN IN1
.W2
CAN IN1
.W3
PDO message with 4 words user data
7
Schematic overview of dynamic PDO mapping for a Receive-PDO
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Control word
CAN IN1
.W1
Input data:
Index 5CA7 / 1 = control word
Index 5CA7 / 2 = CAN.IN1.W1
Index 5CA7 / 3 = CAN-IN1.W2
Index 5CA7 / 4 = CAN-IN1.W3
:
:
CAN IN1
.W2
CAN-IN1
.W3
Existing process data of
the slave