Civil Engineering Reference
In-Depth Information
Fig. 4.14
State machine of an electrical drive according to CiA 402
also defines a default PDO mapping. According to the defined PDO mapping, 8 × 8
digital input signals are located in the first TPDO and 4 × 16-bit analog input values
in the following three TPDOs. In the first RPDO 8 × 8 digital output signals and
in the three following RPDOs 4 × 16-bit digital output values are located. Further
digital and analog I/O signals could be placed in manufacturer-specific PDOs. All
default PDOs are valid and have a predefined CAN identifier. They are transmitted
event driven (transmission type: 255). The event is a configured trigger condition.
Furthermore, all TPDOs that are not switched off generally are transmitted when a
transition from pre-operational state into operational state occurs.
The device profile CiA 401 supports a digital granularity of 8 bytes per default.
1-bit, 16-bit and 32-bit accesses are optionally provided. Analog modules have a
16-bit resolution specified per default. Alternatively, analog 8-bit values, 32-bit val-
ues as well as floating-point arithmetic and manufacturer-specific analog formats
can be implemented.
Some of the CANopen device profiles also specify application-specific state ma-
chines. The state machine, shown in Fig.
4.14
, is described in the drives and mo-
tion control profile CiA 402 (see IEC 61800-7). It is controlled by a control word
(6040
h
) received via RPDO. After a state transition, the CANopen device transmits
the status word (6041
h
) to the host controller for purpose of acknowledgement on
the application level.
