Siemens SINUMERIK 840C Installation Instructions Manual page 310

12.93
Bit 2 Bit 2=1 Must be set when a function calling for a spindle encoder is required, e.g.
• G33/34/35
• G 95
• G 96
• G 97
• M 19
The encoder is allocated in MD 400*, which also activates the hardware
monitor for the measuring circuits. If the M19 option is invoked, bit 2 must be
set to 1 (also see Section entitled "Axis (Analog) and Spindle Installation").
Bit 1 Bit 1=1 The sign of the spindle encoder pulses is inverted every time this bit changes
its status.
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Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
6 NC Machine Data (NC MD), NC Setting Data (NC SD)
6.6.2 Spindle-specific MD bits (spindle bits)
(Thread cutting)
(Feedrate per revolution)
(Constant cutting speed)
(Freeze spindle speed)
(Oriented spindle stop)
6FC5197- AA50
6–125