Detailed Description   
2.9 Program control 
  Mode Group, Channel, Program Operation, Reset Response (K1) 
2-124  Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0 
SD42990 
Setting data SD42990 $SC_MAX_BLOCKS_IN_IPOBUFFER can be used to dynamically 
limit the number of blocks in the interpolation buffer to a smaller value than that in 
MD28060 $MC_MM_IPO_BUFFER_SIZE; the minimum number is 2 blocks. 
Values of setting data SD42990 $SC_MAX_BLOCKS_IN_IPOBUFFER: 
 
Value  Effect 
< 0  No interpolation buffer limit active. 
The max. possible interpolation buffer as set in MD 28060: 
MM_IPO_BUFFER_SIZE is activated. 
or 1  The minimum permissible interpolation buffer with 2 blocks is activated. 
< MM_IPO_BUFFER_SIZE  The interpolation buffer is activated with no more than the maximum specified 
number of blocks. 
>= MM_IPO_BUFFER_SIZE  The interpolation buffer is activated with the number of blocks specified in MD 
28060: 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. 
 
Validity 
SD42990 $SC_MAX_BLOCK_IN_IPOBUFFER has global, channel-specific validity and can 
also be modified in a part program. This modified value is maintained at program end. If this 
setting data is to be reset again on defined events, a so-called event-driven program must be 
created to do this. For example, this setting data could always be set to a predefined value 
on RESET. 
Application 
The IPO buffer limitation can be used whenever the number of blocks between block 
preparation and interpolation must be minimized, e.g., when actual positions in the part 
program must be read and processed for other purposes.