A4: Digital and analog NCK I/Os for SINUMERIK 840D sl
1.2 Access via PLC
Extended Functions
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
51
1.2.6.2 Supplementary conditions
Configuration
● If the PLC I/Os are to be written/read via the fast data channel, they must always be
configured as a cohesive block (i.e. no address gaps within this block).
● It must be possible for the number of bytes that have to be transferred to be mapped
without gaps on the PLC I/Os.
Time response
The time when the data is read in from the PLC I/Os is not synchronized with the time when
the data is made available to the part program via system variables!
Data transfer (NCK ↔ PLC)
● The data buffer is always output complete to the PLC I/Os, even if only one system
variable was assigned within the data buffer.
● If values are assigned to several system variables simultaneously (e.g. for initializing the
PLC I/Os), there is no guarantee that they will be transferred in the same interpolation
cycle.
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