Siemens SINUMERIK 840D sl Programming Manual page 622

Work preparation
3.7 Special motion commands
Measurement results for MEASA / MEAWA
The values measured by probes can be read through the following system variables in the part
program and in synchronized actions.
System variable
$AA_MM1[<Axis>]
...
$AA_MM4[<Axis>]
$AA_MW1[<Axis>]
...
$AA_MW4[<Axis>]
<Axis> = measuring axis
If a measuring job is executed by two measuring systems, each of the two possible trigger
events is acquired from both measuring systems. The assignment of system variables is then
as follows:
$AA_MM1[<Axis>]
$AA_MM2[<Axis>]
$AA_MM3[<Axis>]
$AA_MM4[<Axis>]
Continuous measurement (MEAC)
The measured values for MEAC are available in the machine coordinate system and stored in
the programmed FIFO[<n>] memory (circular buffer). 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 specifically for this purpose (defined in machine data).
The FIFO memory is a circular buffer in which measured values are written to $AC_FIFO
variables according to the circular principle.
Note
FIFO contents can be read only once from the circular buffer. If this measured data is to be used
several times, it must be buffered in the 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 least with the same frequency as new measured values
are input.
Further information: Function Manual Synchronized Actions
622
Meaning
Probe measured value for trigger event 1 in the machine coordinate system
...
Probe measured value for trigger event 4 in the machine coordinate system
Probe measured value for trigger event 1 in the workpiece coordinate system
...
Probe measured value for trigger event 4 in the workpiece coordinate system
or $AA_MW1[<Axis>]
or $AA_MW2[<Axis>]
or $AA_MW3[<Axis>]
or $AA_MW4[<Axis>]
Measured value from measuring sys‐
tem 1 on trigger event 1
Measured value from measuring sys‐
tem 2 on trigger event 1
Measured value from measuring sys‐
tem 1 on trigger event 2
Measured value from measuring sys‐
tem 2 on trigger event 2
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming