Siemens SIMOVERT MASTERDRIVES Manual page 195

05.2006
Homing mode
(REF_ON)
From V1.6
Siemens AG 6SE7087-6QX70 (Version AG)
SIMOVERT MASTERDRIVES
In the setup mode with linear axis, the software limit switches become
effective after homing.
The cycle length of a rotary axis is entered in the parameter U858 (axis
cycle) in LU. U858 should be set to 0 in the case of a linear axis. The
value (–1) in index 2 means that the value for index 2 = corresponds to
the value in index 1.
The correction and homing block always provides the functionality. The
associated function block can be found in function diagram 789c and is
assigned to a time slot using parameter U953.62.
The homing mode is employed when incremental path encoders are
used, as there is no relationship between the measuring system
(incremental path encoder) and the mechanical position of the axis
when the drive is switched on.
In this mode, a basic distinction is made between two types of homing.
The type of homing depends on the selected homing type REF_TYP,
which is set using parameter U875.10 or source U866.9.
The following settings are possible:
♦ REF_TYP = 0: Homing on the fly (post-homing)
♦ REF_TYP = 1: Homing movement in preferred direction and
sequence control with reversing cams.
Homing on the fly REF_TYP = 0
Homing on the fly means setting the position setpoint and actual value
simultaneously. This is implemented in the basic unit by position
correction of the position detection and of the position setpoint of the
position controller.
A reference position REF_setpoint is specified for this in U874.2.
Alternatively, this reference position can be transferred via the
connector to parameter U877.3.
The correction of position setpoint and position actual-value is always
performed irrespective of the direction of rotation, unless (from V1.6)
the direct setting of REF_D_REF is activated at the correction block
(function diagram 789c) with REF_D_REF_EN = 1.
Signal SET_REF_D (B0895) always shows the status of REF_D (input
Src U866.14 preferred direction). This is linked with the input
REF_D_REF at U878.5 (factory setting), which also enables the
direction to be evaluated during homing on the fly (function diagram
789c).
If the current direction of rotation corresponds to [SET_REF_D]
(B0895), (1 = counter-clockwise / 0 = clockwise) and a valid measured
value is received, a correction is carried out by means of "Start Ref."
taking the "skip window" into account.
Compendium Motion Control
Functions
7-29