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Appendix | EtherCAT Documentation
optoNCDT 1900 / EtherCAT
A 5.2.7
Process Data PDO Mapping
Process Data Objects (PDOs) are used for the exchange of time-critical process data between master and slaves. Tx PDOs are used
to transfer data from the slave to the master (inputs). Rx PDOs are used to transfer data from the master to the slave (outputs); this
concept is not used in sensor. The PDO mapping defines which application objects (measurement data) are transmitted into a PDO.
You can choose from a series of Tx PDO mapping objects.
In EtherCAT the PDOs are transported in objects of the Sync Manager channel. The sensor uses the Sync Manager channel SM3 for
input data (Tx data). The PDO assignments of the Sync Manager can only be changed in the “Pre-Operational” state.
Note:
Subindex 0h of the object 0x1A00 contains the number of valid entries within the mapping report. This number also represents
the number of application variables (parameters) that should be transmitted/received with the corresponding PDO. The subindices
from 1h up to the number of objects contain information about the depicted application variables. The mapping values in the CANo-
pen objects are coded in hexadecimal form.
The following table contains an example of the entry structure of the PDO mapping:
MSB
LSB
31
16 15
8 7
0
Index e.g. 0x6000
(16 bit)
Subindex e.g. 0x01
Object length in bits,
e.g. 20h = 32 bits
Fig. 34 Entry structure of the PDO mapping, example
A 5.2.8
Service Data SDO Service
Service Data Objects (SDOs) are primarily used for the transmission of data that are not time critical, e.g. parameter values.
EtherCAT specifications
- SDO services make possible the read/write access to entries in the CoE object directory of the device.
- SDO information services make it possible to read the object directory itself and to access the properties of the objects.
All parameters of the measuring device can be read or changed in this way, and measurements can be transmitted. A desired param-
eter is addressed via index and subindex within the object directory.
Summary of Contents for ILD1900-10
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