Actual Value Link; Setpoint Velocity/Actual Position Link (Sw 4 And Higher); General; Parameterization - Siemens SINUMERIK 840C Installation Instructions Manual

10.94
12.18.4.2

Actual value link

The setpoint link described above cannot be used in some cases. This applies particularly to
leading and following drives which differ greatly in terms of dynamic response or to leading
drives, such as spindles which are not position-controlled.
With an actual value link, the command variable for the controlled following drive is derived
exclusively from the part actual values of the leading drives and from any overlay of the
following drive. In this case, the dynamic response of the following drive should be
considerably better than that of the leading drive (not vice versa under any circumstances).
In this case, the individual drives are optimally adjusted according to their dynamic
performance.
The following drive always registers disturbing torques on the leading drive as setpoint
changes and follows them accordingly.
Leading axes (electric handwheels, PLC auxiliary axes, hydraulic axes, etc.) which are not
position-controlled may only be operated in an actual-position link; a position measuring
system is always required.
12.18.4.3

Setpoint velocity/actual position link (SW 4 and higher)

General

The "Setpoint velocity/actual position link" is available as an alternative link type K4 with
software version 4 for ELG/synchronous spindle applications. This is an actual position link
(corresponding to the existing link type K2); however, its feedforward control path is supplied
by the setpoints of the leading axes/spindles (instead of by the "less steady" actual values for
link type K2). To ensure that the dynamic response of the leading and following axis(axes) is
effectively matched, an independent "Time constant setpoint velocity link K4" (MD3300* or
2567*) has been introduced as a new feature. When the dynamic response values of the
leading and following axis/axes are identical, the values of the existing "Time constant setpoint
filter" (MD 1272* or 486*) must be applied. With different dynamic response values, the
dynamic response can be matched in relation to the dominant leading axis.

Parameterization

If several leading drives are controlling a following drive by means of link type K4, then it must
be noted that the "Time constant setpoint filter" (K4) is available only once for the entire ELG
grouping, i.e. jointly for all K4 leading drives. For this reason, it is not advisable to link several
leading drives with K4 link to a following drive unless
• all the K4 leading drives have the same dynamic response from the outset or
• the dynamic response of all K4 leading drives has been matched by means of the "Time
constant setpoint smoothing" function (MD 1272* or 486*).
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
12.18.4 Link types with constant link factor
6FC5197- AA50
12 Functional Descriptions
12–133