
11.APPLYCATION OF OTHER FUNCTIONS B-63494EN/02
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11.2 EXTERNAL DECELERATION
11.2.1 Overview
The dual check safety function uses the CNC CPU and monitor DSP
to separately monitor the specified speed of the feed axis (safe speed
monitoring function). When one or more axes have a speed greater
than or equal to the safe speed in safe signal mode B (in a state where
a guard open request is input and the guard is closed), the guard lock
cancellation signal *LGD is set to 0 to disallow the cancellation of
guard lock. When one or more axes have a speed greater than or equal
to the safe speed in safe signal mode C (in a state where a guard open
request is input and the guard is open), servo alarm 476 or 494 occurs
and power to the motor driving circuit is interrupted.
The external deceleration function decelerates the speed of the feed
axis to the external deceleration speed specified in the parameter by
inputting the external deceleration signal. A maximum of three
external deceleration speeds can be set.
The dual check safety function and external deceleration function can
be used to construct a machine that operates as shown below.
• Automatically reduces the speed of the feed axis to the safe speed
or below in safe signal mode B to allow the opening of the guard.
• Limits the speed of the feed axis within the safe speed in safe
signal mode C to prevent an alarm from being issued by the safe
speed monitoring function.
The external deceleration function is optional.
For speed control of the spindle, see Section 11.3, "SPINDLE
OUTPUT CONTROL BY THE PMC."