Data Exchange; Communication Via Part Programs/Synchronous Actions - Siemens SINUMERIK Series Function Manual

A4: Digital and analog NCK I/Os for SINUMERIK 840D sl
1.3 Access via PROFIBUS
1.3.3

Data exchange

The following requirements must be satisfied for direct data exchange with the PROFIBUS
I/O via the NCK-internal PROFIBUS communication interface:
● Correct configuration of the corresponding I/O ranges.
● PLC must actually be able to provide the required I/O ranges (user data slots).
● The configured I/O ranges are released for use only when the PROFIBUS communication
1.3.3.1

Communication via part programs/synchronous actions

General
The NCK global system variables enable access to the PROFIBUS I/O, whether read or
write, from the part programs / synchronized actions:
● $A_DPx_IN [<n>,<m>]
● $A_DPx_OUT [<n>,<m>]
The following must be observed:
● When reading from or writing to these variables from a part program, a preprocessing
● To ensure data consistency during programming from the part program and the
● If the same PROFIBUS I/O data is to be write-accessed several times within an IPO cycle
● The PROFIBUS I/O data to be written is output at the PROFIBUS I/O only after the
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interface is able to do a data exchange with the corresponding PROFIBUS I/O for the first
time.
stop is triggered.
synchronized actions, the PROFIBUS I/O data is accessed which is kept consistent for
the respective IPO cycle.
(e.g. synchronized actions, access from different channels, etc.), then the data of the last
write access is valid.
corresponding IPO cycle.
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
Extended Functions