
2.PROFIBUS-DP SLAVE FUNCTIONS SETTING B-63994EN/02
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On the contrary, when an input signal from the master is processed by
the ladder program, the data of the register written by one refresh
processing operation by the PROFIBUS-DP slave function may not be
able to be read by one ladder program processing operation.
CAUTION
Ladder program processing is not synchronous
with DI/DO data refresh processing by the
PROFIBUS-DP slave function. Therefore, keep the
following in mind when creating a ladder program.
(1) When the input signal of PROFIBUS-DP is
read at two points in the ladder program, even
though the read operation is completed in the
same cycle of the ladder program, there is no
guarantee that the same value will be read.
(2) When the ladder program writes the
PROFIBUS-DP output signal in the specified
PMC address, the signal may be transferred to
a master device before the ladder program is
completely executed.
(3) The concurrency of data is guaranteed for up
to 4 bytes. To guarantee the concurrency of
data, some constrains are imposed. For
details, see the next item "Data concurrency".
NOTE
The DI/DO data refresh time of the PROFIBUS-DP
slave function is 8 msec.