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Appendix |EtherCAT Documentation
confocalDT 24x1
In order to ensure that no samples will disappear, due to the high asymmetry between master cycle and
slave cycle, the master cycle time is subject to be less than the time which is required for the generation
of a block consisting of x samples.
A complete block is generated from the stated samples and first presented to the EtherCAT side after
all stated samples have been written into the block. If the time for the writing into the block is shorter
than the master cycle time, unfortunately single blocks cannot be transmitted. It can happen that the
next block has already been filled with samples, before the previous filled block has been picked up
with a master cycle.
Block
10 samples at a distance 100 µs = 1 ms
Master cycle > 1 ms
not transmitted blocks
Time for n samples < master cycle time
10 samples = 1 ms
If the number of samples selected is to high, i.e. the time for the filling of a block is longer than the
master cycle time, each block is picked up by a master cycle. However, single blocks and therefore
samples are transmitted twice or even more often. This can be detected on the master side by the
transmission of the Timestamp or Valuecounter, see object 0x21B0.
Block
12 samples at a distance 100 µs = 1.2 ms
Master cycle < 1 ms
Time for n samples > master cycle time
12 samples = 1.2 ms
double (multiple) transmitted blocks
