Introduction
ATM60-Cxx 03/2007 7
CANopen therefore restricts the flexibility of CAL to two data objects, “Service Data Objects” (SDO) for the
transmission of large data blocks, and “Process Data Objects” (PDO) for the real-time transmission of
process data. With the restriction to these two data types, the number of CMS objects for each device is also
reduced at the same time. This simplifies communication and helps to keep the volume of the communication
profile small.
4.3.2 CANopen device profiles
In the industrial sector, a large number of standards has led to a modular system for standard tasks, from
which one may choose relatively freely when constructing a system, without being referred to specific
manufacturers in the process. By means of device profiles, CANopen intends to expand this situation to the
sector of networked components as well. As a compromise between strict regimentation, scalability and
openness for future developments, a device profile comprises three sections:
· “Mandatory Functionality” comprises all device functions which must absolutely be present in order to
conform to the respective profile.
· “Optional Functionality” describes how optional functions are to be implemented. This means that,
although they are not prescribed, when they are present then they are defined as here.
· “Manufacturer Specific Functionality” is, finally, the section in which each manufacturer can describe his
individual functions and expansions.
For the ATM60-Cxx, the profile for encoders DSP 406 is definitive.
This profile describes a manufacturer-independent definition for encoders. It is divided into two device
classes:
· Class 1
Describes all the basic functions which the encoder must contain.
· Class 2
Contains a large number of expanded functions which must be supported by this class of encoders
(mandatory) or are optional.
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