Siemens sinumerik 840d Programming Manual page 182

Special Motion Commands
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5.7 Extended measuring function MEASA, MEAWA, MEAC
840D 840D
NCU 571 NCU 572
NCU 573
Measuring job status for MEASA, MEAWA
If the probe switching state needs to be evaluated in
the program, then the measuring job status can be
interrogated via $AC_MEA[n], with n = number of
probe.
Once all the trigger events of probe "n" that are
programmed in a block have occurred, this variable
switches to the "1" stage. Its value is otherwise 0.
If measuring is started from synchronized actions,
$AC_MEA is not updated. In this case, new PLC
status signals DB(31–48) DBB62 bit 3 or the
equivalent variable $AA_MEAACT["Axis"] must be
interrogated.
Meaning: $AA_MEAACT==1: Measuring active
$AA_MEAACT==0: Measuring not active
References: /FB/ M5, Measurement
Continuous measurement MEAC
The measured values for MEAC are available in the
machine coordinate system and stored in the
programmed FIFO[n] memory (circulating memory).
If two probes are configured for the measurement,
the measured values of the second probe are stored
separately in the FIFO[n+1] memory configured
especially for this purpose (defined in machine data).
The FIFO memory is a circulating memory in which
measured values are written to $AC_FIFO variables
according to the circulation principle.
References: /PGA/ Chapter 10, synchronized actions
Additional notes
• FIFO contents can be read only once from the
circulating storage. If these measured data are to be
used multiply, they must be buffered in user data.
• If the number of measured values for the FIFO
memory exceeds the maximum value defined in
machine data, the measurement is automatically
terminated.
• An endless measuring process can be implemented
by reading out measured values cyclically. In this
case, data must be read out at the same frequency
as new measured values are read in.
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810D 840Di
CCU 2
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide Advanced (PGA) − 04.00 Edition
08.97 04.00
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