Limitations, special cases
Limitation of the look-ahead range
The described look-ahead range is limited due to resource limitation and the requirement for the NC program to run up as soon as possible after start.
The default limits the maximum number of blocks considered for pre-output to 10 blocks; this can be set in P-CHAN-00603 (or in P-STUP-00061). Depending on the block length, this results in a maximum joint width.
If an M/H function is brought forward beyond the look-ahead range, the M/H function is only brought forward automatically as far as the look-ahead range permits.
Programming Example
Limitation of the look-ahead range
Explicit cancellation of the look-ahead range, #FLUSH, Read synchronous V.E. variable
The look-ahead range of M functions is reset by flushing the channel (#FLUSH or #FLUSH WAIT). In other words, the pre-output of M functions cannot be reversed beyond the #FLUSH point.
An implicit #FLUSH WAIT, i.e. the channel is flushed, can also be executed when a synchronous V.E variable (see [EXTV]) is read. A pre-output via the read access of a synchronous V.E. variable is therefore not possible either.
If an M/H function is brought forward beyond the look-ahead range, the M/H function is only brought forward automatically as far as the look-ahead range permits.
Programming Example
Explicit cancellation of the look-ahead range, #FLUSH, Read synchronous V.E. variable
"Overlapping" path-related pre-output
After a path-related pre-output of the M function is detected, all previously stored motion blocks are output. This corresponds to explicit flushing of the channel (see #FLUSH), thus avoiding delayed processing of the motion blocks.
As a result, it is not possible to overlap the path range of several M functions.
If pre-outputs of M/H functions overlap, the individual M/H functions are only brought forward automatically up to the originally programmed position.
Programming Example
"Overlapping" path-related pre-output
Combination of MNS_SNS with and without pre-output path
Programming Example
Combination of MNS_SNS with and without pre-output path
Pre-output between output and synchronisation points of an MVS_SNS
It is not possible to insert an M/H function of synchronisation type MVS_SNS between output and synchronisation points. The pre-output of the M/H function is then only brought forward up to synchronisation point of the MCS_SNS at the most.
Programming Example
Pre-output of another M/H function of the MVS_SNS type
The example below shows an attemptyto move M100 between the output and synchronisation points of the M200 (an MVS_SNS with motion). In this case, M100 is not output as required at X9 but at the end of N10, i.e. at X10.
