Lenze PLC Designer PLC Designer (R2-x) CANopen for Runtime Systems - Manual (Page 46)

L-force | PLC Designer - CANopen for Runtime Systems
CAN network variables
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DMS 2.0 EN 05/2009 TD29 45
The options and their meaning:
- Network type: one of the network types which are defined in the Target Settings dialog (tab
'Networkfunctionality').
- Read: The values of the variables in this list should be read by one or several of the other PLCs in
the network.
- Write: The values of the variables in this list should be sent to other PLCs. It is recommended to
set only one of the options "Read" or "Write" for a variables list. If some variables of a project
should be read and written, then use two variables lists: one for reading, one for writing. Besides
that it is recommended to have only one PLC in a network which is used to send a certain
variables list.
- Cyclic Transmission: Only valid, if „Write“ is activated. The values will be sent in the defined
Interval, no matter whether they have changed or not.
- Transmission at Change: The values will only be sent in case they have changed or when the
time, set at Min. interval, is over.
- Pack Variables: If this option is activated, as many variables as possible will be packed in one
transmission unit. For UDP a transmission unit has a maximum size of 256 Bytes, for CAN 8
Bytes. If one transmission unit is to small to catch all variables, then further units will be generated.
If the option is deactivated, each variable will be packed in a separate transmission unit. If
‘Transmission at Change’ is activated, for each particular transmission unit it will be checked
whether it has been changed and is to be sent.
- List identifier (COBID): This is an unique identifier to mark the variables lists which should be
exchanged between several projects. Only lists which have the same identifier can exchange their
data. But assure that the lists, which have the same identifier, also contain identical definitions! For
this it is recommended to use the feature Link to file to export the desired variable list from one
project and to import it into the other projects.
WARNING: In a CAN network the list identifier will be used directly as COBID of the CAN
message(s). There’s no check for collisions of identifiers used here and the ones which are used
in the CANopen-configuration for IO-PDOs.
To exchange data properly between two controllers, the definition of the variable lists in the two
projects must be same. You can use the “Link to file” feature to assure that both projects use the
same variable list. One project should export the file before compile, the other projects import it before
compile.
Besides simple data types, a variable list may also contain structures and arrays. Elements of these
compound data types are sent individually
If a variable list is bigger than the PDO size of the respective network, it is sent using several PDOs.
This means that it can not be assured that all data of a variable list is received in the same cycle.
Portions of the variable list may arrive in different PLC cycles. This can happen also for variables of
array or structure data types.
Options not supported for CAN:
- Transfer checksum.
- Answer bootup requests.
- Confirmed transfer.
- Request on Bootup.