Different Position Control Cycles - Siemens SINUMERIK 840D sl Function Manual

Several Operator Panels on Several NCUs, Distributed Systems (B3)
2.12 NCU link with different interpolation cycles
2.12.2

Different position control cycles

The general solution described in Section "Diagram of general solution" also permits
different position control cycles for NCU-A/NCU-B and NCU-U as illustrated in the diagram
"Schematic example of a configuration with several NCUs and eccentric machining unit"
(Section "Diagram of general solution").
By setting the parameters as described below, you can improve the quality for some
controller types.
When interpolating, the different cycle times are detected in fine interpolation and in the
position control due to the different position control cycles; they are compensated for
internally by delaying the setpoints for the axes with the faster position control cycle.
Standard result
If the axis with the slower position control cycle is not accelerated or is only accelerated very
slowly, contour errors are largely avoided. However, contour errors will always occur when
accelerating, therefore accelerations should not take place while machining.
Special MD settings
In some cases, it may be necessary to be able to adapt the delay (see examples below).
This machine data was introduced for this purpose:
MD10065 $MN_POSCTRL_DESVAL_DELAY
It allows you to adapt the setpoint delay in the position controller for the entire NCU. You can
use positive and negative values. The set values (time in seconds, max. +/- 0.1sec) are
added to the automatically calculated values. See under "Information" below.
Setting notes
The required position setpoint delay depends on the controller structure used (DSC (dynamic
stiffness control), feedforward control); this delay is taken into account when switching to the
respective controller (e.g. FFWON (travel with feedforward control ON)). The automatic setting
function obtains the maximum value for the position control cycles of the individual NCUs
and delays the times on all the NCUs, thus providing compensation at constant speed for the
different cycle times on all types of controller structures. In this manner, an additional delay
can even be active on the axis with the slowest position control cycle.
The controller structure with
● the highest compensation requirement is operation of torque feedforward control or with
● the least compensation requirement is DSC or if feedforward control is deactivated.
186
speed feedforward control and activated ramp encoder in the drive,
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions