Dead-Time Compensation; Protection Zone Collision - Siemens SINUMERIK 840C Installation Instructions Manual

12 Functional Descriptions

12.32.10 Dead-time compensation

12.32.10 Dead-time compensation
Because of the internal structure of the software, dead-time compensation must be performed
for all motion axes functioning as ELG following axes. The dead time to be compensated is
specified in the axis-specific machine data.
Dead times:
ELG following axes with setpoint coupling:
ELG following axes with actual value coupling:
Axis-specific machine data
Dead-time compensation value:
12.32.11

Protection zone collision

Because the internal traverse enable for the motion axes involved can only be canceled with a
protection zone distance of zero, it is possible that the two protection zones might overlap as
the result of a collision. The overlap is larger:
• the larger the IPO sampling time
• the larger the maximum velocity
• the larger the maximum reduction factor
• the smaller the acceleration
• the smaller the maximum jerk
It is therefore advisable not to fit the protection zones exactly round the machine parts to be
protected.
By selecting appropriate values for the above parameters, especially the minimum reduction
factor, it is advisable to achieve an overlap of less than 1 mm in any case.
Formulas
Calculation of jerk r, acceleration a and velocity v with respect to the path per IPO cycle.
mm
m
r =r
IPO 3
T
s 3
mm
m
a =a
IPO 2
T
2
s
mm
m
v =v
T
min
IPO
12–322
2 IPO cycles
5.5 IPO cycles
MD 3932*
IPO 3
T [ms]
·
10 6
IPO 2
T [ms]
·
1000
T [ms]
IPO
·
60
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