Special features and restrictions

Restrictions / special features

If multiple "empty" rows are programmed in the NC program that are only evaluated internally in the decoder, no commands are output to the NC channel.

In particular in the case of block ahead limiting via "MAX_NC_BLOCKS_AHEAD", this can lead to a situation in which decoding is interrupted because the channel no longer supplies any new blocks (jamming).

To avoid this, no large blocks of comment lines, empty rows, parameter calculations, etc. should occur if possible after block ahead limiting is selected.

It may also be necessary to increase the block ahead limit value.

Notice

notice

To ensure that no jamming of the NC channel occurs when decoder block ahead is limited, you are advised to define a limit of at least 10 rows.

Since path preparation saves a different number of blocks depending on the active functions in the NC channel, a considerably higher block ahead limit may be required.

The overall storage effect of the channel depends on the following active functions, for example:

Depending on the path dynamics, feed rate fluctuations may occur when block ahead limiting is active if motion blocks are relatively short.

Notice

notice

For stable execution, monitored block ahead mode can be optionally selected by the channel parameter P-CHAN-00270, see Section “Time-related block ahead limiting”):

dec_max_ahead_protected ACTIVE