Siemens SINUMERIK 840C - Page 998

09.95 12 Functional Descriptions
12.19.7 Retraction
The following individual sources are also available:
• Axis/spindle-specific sources:
- Retraction threshold FA/FS exceeded
- DC link voltage warning threshold
- Generator minimum speed limit
Activation of sources:
The user determines which of the possible axis sources initiate a retraction and which do
not in an axis-specific and spindle-specific MD byte NC MD 530* 596*.
• Sources specific to channel/mode group and general sources:
- Mode group stop of channel mode group
- EMERGENCY STOP
Activation of sources:
The user determines which sources are active and which are not in a channel-specific MD
byte NC-MD 920*.
• External sources via HW inputs:
A retraction process can be initiated from and external source (provided input is active) by
means of a mode group-specific input byte of the mixed I/O or CSB (can be defined by
means of MD).
Activation of input bits:
An MD byte NC-MD 922* is assigned to each channel; this byte is used to define which
input bits are active and which are not.
A retraction process is initiated if a low-level signal is present at an active input bit of the
mixed I/O, i.e. low-active inputs; 24 V must be applied to the active inputs before the
retraction is enabled.
Note:
Emergency retraction is only applied to axes that are under closed-loop control (i.e. controller
enable must be set).
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 12–223
SINUMERIK 840C (IA)