
B-64004EN/02 3.SAFETY FUNCTIONS
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3.18 SAFE STOP MONITORING
When a safety door is open, safe stop monitoring for servo axis and
spindle can be realized by the combination of several functions.
Safe stop monitoring for servo axis
According to the safe speed monitoring for servo axis and the safe
positing error monitoring, CNC and Servo monitor actual feedrate and
deviation of each axis. When a safety door is open, monitoring of stop
condition of each axis can be performed by the combination of the
following three functions.
a) By the safety speed monitoring function, check whether the
actual feed rate is lower than the safety level. If the feedrate
exceeds the safety limit, an alarm is generated.
Actual speed is calculated with the feedback of a position
detector. So, even if command feedrate is 0, actual feedrate may
be detected as not 0 when an axis is moved by external power.
Set the value of safety limit that does not cause an alarm when
feedrate command is 0.
b) By the safe positioning error monitoring function, check whether
position deviation is within a safety limit. If an axis is moved
unexpectedly, an alarm is generated.
c) According to “Axis moving signal MVx (Fn102)”, check
whether axis motion command is not given. (Axis moving signal
is prepared for PMC and is not double check signal.)
Safe stop monitoring for spindle
According to the safe speed monitoring for spindle, CNC and Spindle
monitor actual speed of each spindle. When a safety door is open,
monitoring of stop condition of each spindle can be performed by the
combination of the following two functions.
a) By the safety speed monitoring function, check whether the
actual speed is lower than the safety level. If the feedrate exceeds
the safety limit, an alarm is generated.
Actual speed is calculated with the feedback of a position
detector. So, even if command speed is 0, actual speed may be
detected as not 0 when a spindle is moved by external power. Set
the value of safety limit that does not cause an alarm when speed
command is 0.
b) There is a possibility that spindle rotate at speed lower than
safety speed limit. Then it is necessary to select the function to
make position control loop, such as spindle positioning, Cs
contouring control or spindle orientation.