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Appendix | EtherCAT Documentation
optoNCDT 1900 / EtherCAT
A 5.6
Oversampling
In operation without oversampling, the last accumulated measured value data set is transferred to the EtherCAT master with each
fieldbus cycle Therefore, for long fieldbus cycle periods data records with measured values are possibly not available. Configurable
oversampling ensures that all (or selected) measured value data records are gathered and transmitted together to the master during
the next fieldbus cycle. In general, a possible oversampling depends on the ratio of sensor measuring rate to fieldbus cycle time.
The oversampling factor specifies how many samples per bus cycle are transmitted. Currently the ILD1900-IE supports oversampling
of 1, 2 and 4. For example, an oversampling factor of 2 means that 2 samples are transferred per bus cycle.
With TxPDO Mapping, see
, the base index of the PDO mapping objects is included with the oversampling factor 1. Use the fol-
lowing list to determine the index for selecting a different oversampling factor:
- Base index + 1: Oversampling factor 2
- Base index + 2: Oversampling factor 4
- Base index + 3: Oversampling factor 8
You can only select mapping objects with the same oversam-
pling factor in 0x1C13h.
Example:
- The fieldbus/EtherCAT master operates at a cycle time of
1 ms because the higher-level PLC works with a cycle time
of 1 ms. This means that every 1 ms, an EtherCAT frame
is sent to the ILD1900-IE to retrieve the process data. If the
measurement frequency in the sensor is set to 4 kHz, an
oversampling factor of 4 must be set.
- Startup procedure to output the distance value with an
oversampling factor of 4.
The distance value is output in object 6007h. In order to
transfer this object in the PDO, the PDO mapping object
0x1A10 must be selected in object 0x1C13:01h. However,
0x1A12 (base index 2) must be selected for the
4-fold oversampling.
To ensure that no samples are lost due to the asynchronous nature between the master cycle and slave cycle, the master cycle time
Summary of Contents for ILD1900-10
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