Siemens SINUMERIK 840D sl Function Manual page 454

Compensations (K3)
Electronic weight compensation (vertical axis)
The amount the axis (Z) is lowered increases in proportion to the speed controller reset time
parameterized with the SIMODRIVE 611, see machine data
MD1409 $MD_SPEEDCTRL_INTEGRATOR_TIME_1
(reset time velocity controller, reset time speed controller)
Through activation of the electronic weight compensation function, it is possible to minimize
the amount by which the axis is lowered.
Activation
The function is set by parameterizing the axis-specific machine data
MD32460 $MA_TORQUE_OFFSET
(additional torque for electr. weight compensation)
to a value other than zero and activated with the next RESET or POWER ON operation or
with softkey "Activate MD".
Axis with electronic weight compensation
The "electronic weight compensation" function prevents weight-bearing axes from sagging
when the control is switched on. After releasing the brake, the constant weight compensation
torque maintains the position of the vertical axis. This process is illustrated in the diagram
below.
Figure 5-40
Note
This function is available only in conjunction with SIMODRIVE 611 digital.
454
Lowering of a vertical axis with electronic weight compensation
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions