Siemens Sinumerik 840D sl Programming Manual page 24

Flexible NC programming
1.1 Variables
<index>:
Example
An automation system contains 2 NCUs (NCU1 and NCU2). Machine axis AX2 is connected
to NCU1. It is traversed as a link axis of NCU2.
NCU1 writes the actual current value ($VA_CURR) of axis AX2 cyclically to the link variables
memory. NCU2 reads the actual current value transmitted via link communication cyclically
and displays alarm 61000 if the limit value is exceeded.
The data structure in the link variables memory is illustrated in the following figure. The actual
current value is transmitted in the REAL value.
NCU1
NCU1 uses link variable $A_DLR[ 16 ] to write the actual current value of axis AX2 to the link
variables memory cyclically in the interpolation cycle in a static synchronized action.
Program code
N111 IDS=1 WHENEVER TRUE DO $A_DLR[16]=$VA_CURR[AX2]
24
Address index in bytes, counted from the start of the link variable memory
Data type:
Range of values:
INT
0 - MAX_INDEX
Note
• MAX_INDEX is calculated from the
parameterized size of the link variables
memory: MAX_INDEX = (MD18700
$MN_MM_SIZEOF_LINKVAR_DATA) - 1
• Only indices may be programmed, so that the
bytes addressed in the link variables memory
are located on a data format limit ⇒
Index = n * bytes, where n = 0, 1, 2, etc.
– $A_DLB[i]: i = 0, 1, 2, etc.
– $A_DLW[i]: i = 0, 2, 4, etc.
– $A_DLD[i]: i = 0, 4, 8, etc.
– $A_DLR[i]: i = 0, 8, 16, etc.
Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
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