Communication Via Compile Cycles - Siemens SINUMERIK 840D sl Function Manual

Digital and Analog NCK I/Os (A4)
NCK I/O via PROFIBUS
Query length of an I/O-range
The configured length an I/O-range can be queried with the help of the following system
variables.
System variables
$A_DP_IN_LENGTH[n]
n = index for the input data range
$A_DP_OUT_LENGTH[n]
n = index for the output data range
Note
● Via <n> (RangeIndex) the corresponding NCK-configured E/A-range is selected. If the
● The <m> (RangeOffset) points to the place (byte-offset) within the I/O-range, from which
● Via the machine data:
1.3.3.2

Communication via compile cycles

General
The CC-bindings are available for reading/printing the data blocks via the compile cycle
interfaces. The access to the data of the I/O-range takes place at the Servo-task level. The
data are updated in each Servo cycle.
Data consistency is thus given for each respective Servo cycle.
To have a write access to the data of the I/O-range via the CC-bindings, the respective I/O-
ranges must be cleared during the NCK-configuration by the machine data:
MD10512 $MN_DPIO_SLOT_ATTRIBUTE_OUT (attributes of the PROFIBUS-I/Os)
for the programming via compile cycles.
A simultaneous programming of these I/O-ranges via part programs/synchronous actions is
prevented by issuing an alarm (17020).
It must be noted that the data is displayed in general in the PLC in the Big-Endian format.
Naturally, this also applies to the PROFIBUS-I/O. Since the bindings support only the byte-
oriented access to data ranges (byte-offset, number of bytes to be transmitted) within an I/O-
range, you must pay attention to the correct display of the data types (16 bit, 32 bit, etc.).
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required I/O-range is not configured, it is indicated by issuing an alarm (17020).
the data access is to be started. Data types can be read/written at any byte-offset within
the I/O-range. Read/write accesses, which exceed the configured limits of the respective
I/O-range, are rejected with the generation of an alarm (17030).
MD10502 $MN_DPIO_RANGE_ATTRIBUTE_IN or
MD10512 $MN_DPIO_RANGE_ATTRIBUTE_OUT
the display format (Little-/Big-Endian) for $A_DPx_IN[n,m]- or $A_DPx_OUT[n,m]-system
variables can be defined for read/write direction as well as for each individual I/O-range.
Description
Reading the length of the input data range
Reading the length of the output data range
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions