HEIDENHAIN TNC 640 (34059x-05) ISO programming - Manual (Page 574)

Test run and program run
17.8 Optional program-run interruption
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TNC 640 | User's ManualDIN/ISO Programming | 1/2015
17.8 Optional program-run interruption
Application
The TNC optionally interrupts program run at blocks containing M1.
If you use M1 in the Program Run mode, the TNC does not switch
off the spindle or coolant.
Do not interrupt program run or test run at blocks
containing M1: Set soft key to
OFF
Interrupt program run or test run at blocks
containing M1: Set soft key to
ON