A4: Digital and analog NCK I/Os for SINUMERIK 840D sl
1.3 Access via PROFIBUS
Extended Functions
58 Function Manual, 03/2013, 6FC5397-1BP40-3BA1
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
interface is able to do a data exchange with the corresponding PROFIBUS I/O for the first
time.
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
stop is triggered.
● To ensure data consistency during programming from the part program and the
synchronized actions, the PROFIBUS I/O data is accessed which is kept consistent for
the respective IPO cycle.
● If the same PROFIBUS I/O data is to be write-accessed several times within an IPO cycle
(e.g. synchronized actions, access from different channels, etc.), then the data of the last
write access is valid.
● The PROFIBUS I/O data to be written is output at the PROFIBUS I/O only after the
corresponding IPO cycle.
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