Siemens SINUMERIK 840D sl Programming Manual page 23

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]
NCU2
NCU2 uses link variable $A_DLR[ 16 ] to read the actual current value of axis AX2 from the
link variables memory cyclically in the interpolation cycle in a static synchronized action. If
the actual current value is greater than 23.0 A, alarm 61000 is displayed.
Program code
N222 IDS=1 WHEN $A_DLR[16] > 23.0 DO SETAL(61000)
Job Planning
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
Flexible NC programming
1.1 Variables
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