# Limiting the number of blocks via channel parameters

## Deactivating via channel parameters

As an alternative, corresponding parameters are available in the channel parameter list to configure block ahead:

max_nc_blocks_ahead <Wert> (P-CHAN-00216)

This parameter defines the maximum number of channel-related NC blocks (rows) by which the decoder may be ahead of the interpolator.

max_motion_blocks_ahead <Wert> (P-CHAN-00246)

This parameter defines the maximum number of NC motion blocks (G00, G01, G02/03) by which the decoder may be ahead of the interpolator.

After program start, the block ahead limit is immediately active and remains selected until the main program ends M30.

The block ahead limit can be modified or deactivated at any time in the NC program by writing the corresponding variable V.G.MAX_NC_BLOCKS_AHEAD or V.G.MAX_MOTION_BLOCKS_AHEAD.

The value set in the channel parameter list then applies again the next time the program is started.

## Attention

Only one block ahead limit option may be activated in the configuration at any one time. When parameters are used at the same time, the error message P-ERR-21574 is output.

## Deactivating via channel parameters

No limit is active after program start if these parameters are set equal to 0 or if they are not specified in the list.