Siemens SINUMERIK 840D Function Manual page 432

M3: Coupled axes
14.2 Curve tables
Memory optimization
In a curve table with linear segments, the linear segments can be stored efficiently in the
memory only if the two following machine data items are > 0:
MD18403 $MC_MM_NUM_CURVE_SEG_LIN (number of linear curve segments in the static
NC memory)
MD18409 $MC_MM_NUM_CURVE_SEG_LIN_DRAM (number of linear curve segments in the
dynamic NC memory)
If no memory areas are created with this machine data, then the linear segments are stored as
polynomial segments.
Alarm in case of insufficient memory
If memory has been configured for tables with linear and polynomial segments via machine
data and memory for linear segments runs out when generating a linear table, the the memory
for polynomial segments is used for the linear segments (if available). In this case, memory is
"wasted", as a polynomial segment requires an unnecessary amount of memory to store a
linear segment. This circumstance is conveyed through an alarm, which also discloses the
number of unnecessarily used polynomial segments. The alarm only displays awarning and
does not result in the interruption of the program or the generation of the curve table.
If a curve table consists of linear segments and polynomials of a high degree, a memory area
for linear segments and a memory area for polynomial segments is required for the storage of
the curve table. An alarm is output if insufficient memory is available in the relevant areas. The
alarm parameters can be used to detect the resources that are insufficient.
Insufficient memory
If a curve table cannot be created, because sufficient memory is not available, then the newly
created table is deleted immediately after the alarm.
If insufficient is available, then one or more table(s) that is/are no longer required can be deleted
with CTABDEL or, alternatively, memory can be reconfigured via machine data.
Temporary curve table
When a curve table is created, a temporary curve table is set up first in memory, which is then
extended block by block. Finally (CTABEND), the table is checked for consistency. The
temporary table is converted to a table that can be used in a coupling only if it is found to be
consistent.
Same table number
A new curve table may have the same number as an existing table. The new curve table then
overwrites the existing table with the same number. This is done only if the new curve table
does not contain any errors. If an error is detected in the new table, the old table is not
overwritten.
If the user wishes to have the option of overwriting an existing curve table without deleting it
first, then he will need to dimension the table memory so that there is always enough extra
memory to accommodate the table to be overwritten.
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Axes and spindles
Function Manual, 06/2019, A5E47437747B AA