Siemens SINUMERIK 840D sl Function Manual page 708

Detailed description
2.9 Program control
2.9.3 Adapting the size of the interpolation buffer
MD28060
The channelspecific interpolator executes prepared blocks from the interpolation buffer
during the part program run. The maximum number of blocks requiring space in the
interpolation buffer at any given point in time is defined by the memory configuring MD28060
$MM_IPO_BUFFER_SIZE (number of NC blocks in the IPO buffer (DRAM)). For some
applications it may be meaningful not to use the full buffer capacity in order to minimize the
"interval" between preparation and interpolation.
SD42990
The number of blocks in the interpolation buffer can be restricted dynamically to a smaller
value than in MD28060 $MC_MM_IPO_BUFFER_SIZE (number of NC blocks in the IPO
buffer (DRAM)), minimum 2 blocks, with the setting data SD42990
$SC_MAX_BLOCKS_IN_IPOBUFFER (max. number of blocks in the IPO buffer).
Values of setting data SD42990 $SC_MAX_BLOCKS_IN_IPOBUFFER:
Value
< 0
or 1
< < MM_IPO_BUFFER_SIZE
>= MM_IPO_BUFFER_SIZE
Note
If SD42990 $SC_MAX_BLOCKS_IN_IPOBUFFER is set in the part program, the
interpolation buffer limitation takes effect immediately if the block with the SD is being
preprocessed by the interpreter.
This means that the limitation of the IPO buffer may take effect a few blocks before the
intended limitation (see also MD 28070 $MC_MM_NUM_BLOCKS_IN_PREP).
To avoid premature activation and to make the limitation of the IPO buffer take effect in
synchronism with the block, a STOPRE (preprocessing stop) must be programmed before
the SD is set in the part program.
150
Effect
No interpolation buffer limit active.
The max. possible interpolation buffer as set in MD 28060:
MM_IPO_BUFFER_SIZE is activated.
The minimum permissible interpolation buffer with 2 blocks is activated.
The interpolation buffer is activated with no more than the maximum specified
number of blocks.
The interpolation buffer is activated with the number of blocks specified in MD
28060: MM_IPO_BUFFER_SIZE.
Basic logic functions: Mode group, channel, program operation, reset response (K1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0