Program Sequence With Preprocessing Memory (Stopfifo, Startfifo, Fifoctrl, Stopre) - Siemens Sinumerik 840D sl Programming Manual

8.3 Program sequence with preprocessing memory (STOPFIFO,
STARTFIFO, FIFOCTRL, STOPRE)
Function
Depending on its expansion level, the control system has a certain quantity of so-called
preprocessing memory in which prepared blocks are stored prior to program execution and
then output as high-speed block sequences while machining is in progress. These sequences
allow short paths to be traversed at a high velocity. Provided that there is sufficient residual
control time available, the preprocessing memory is always filled.
Designate machining step
The beginning and end of the machining step to be buffered in the preprocessing memory are
identified in the part program with STOPFIFO and STARTFIFO respectively. The processing
of the preprocessed and buffered blocks starts only after the STARTFIFO command or if the
preprocessing memory is full.
Automatic preprocessing memory control
Automatic preprocessing memory control is called with the FIFOCTRL command. FIFOCTRL
initially works just like STOPFIFO. Whatever the programming, processing will not start until
the preprocessing memory is full. However, the response to the emptying of the
preprocessing memory does differ: With FIFOCTRL, the path velocity is reduced increasingly
once the fill level reaches 2/3 in order to prevent complete emptying and deceleration to
standstill.
Preprocessing stop
Programming the STOPRE command in a block will stop block preprocessing and buffering.
The following block is not executed until all preprocessed and saved blocks have been
executed in full. The preceding block is halted in exact stop (as with G9).
Job planning
Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
8.3 Program sequence with preprocessing memory (STOPFIFO,
Path traversing behavior
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