num parameter manual - Documentation CN

Equation for KVAR as a function of the time constant (Τ (in s) = 1/Gain):
KVAR = (29491 / (VMAX x Τ)) x k
Where:
- Τ : Position servo-loop time constant (s),
- VMAX : Maximum axis speed (mm/s or deg/s),
- k: Internal measurement coefficient.
! CAUTION
The following error displayed on the CNC is in internal units (ten-thousandths of a degree or
from 0.01 μm to 0.01 μm).
For setting and monitoring P21, parameter P55, i.e. the speed anticipation coefficient, must
be set to zero.
Equation for the Gain
In practice, the gain is often expressed in m/min/min of following error.
A gain of 1 m/min/min corresponds to a gain:
G = 1000/60 x 1 = 16.66 s-1 and a time constant of:
Τ = 1/16.66 = 0.060 s, i.e. 60 ms.
Example
Calculation of KVAR for the axis at physical address 0 (VMAX = 100 mm/s, T = 60 ms, i.e. 0.06 s, internal unit μm).
KVAR = 29491 / (100 x 0.06) x 1 = 4915.16
Word N0 4915
Programme Parameters
Programme parameters E980xx (x: axis number from 0 to 31) are used to read or write servo-system loop gain
coefficients whose value is expressed in thousandths.
UNI-TE request (see UNI-TE Protocol User’s Manual)
The servo-system loop gain coefficients can be modified by a UNI-TE request. A reset (CNC reset) resets the CNC
to the state specified by P21.
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