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8-4
Drive Functions
8.2
Establishing the Position Data Reference
Base package of all variants with closed-loop characteristic
General Information on Establishing the Position Data Reference
Relative Measuring Systems
Absolute Measuring Systems
Establishing the Position Data
Reference
Displaying the Position Data
Reference
Motor Encoder and External
Encoders
Brief Description
During the initial commissioning of a drive the actual position values
transmitted by the measuring systems do not yet have any reference to
the machine axis. This applies to
• relative measuring systems and
• absolute measuring systems.
For more detailed information on relative and absolute evaluation of
measuring systems see "Absolute Measuring Systems" in chapter "Motor,
Mechanical Axis System, Measuring Systems".
The position data reference of a relative measuring system to the axis
has to be reestablished after each time the drive is switched on or after
the position data reference is lost. To do this, the drive has to move to a
defined axis position and the actual position value has to be set to an
axis-related value at a defined position (exception: a relative encoder with
distance-coded reference marks only requires passing two marks!).
The position data reference of an absolute measuring system to the axis
has to be established once during initial commissioning after replacing the
motor or encoder (motor encoder or external encoder) and changes in the
mechanical axis system. The position data reference still is maintained
and the actual position values are axis-related immediately after the drive
is switched on.
After the master has triggered a command corresponding to the kind of
measuring system, the drive automatically establishes the position data
reference according to the following sequence:
• In the case of a relative measuring system without distance-coded
reference marks, the axis moves to the reference point and then
automatically switches to axis-related actual position values.
• In the case of a relative measuring system with distance-coded
reference marks, the axis moves between two reference marks and
then automatically switches to axis-related actual position values.
• In the case of an absolute measuring system, the automatic switching
to the axis-related actual position value is carried out with the axis in
standstill.
The presettings for establishing the position data reference are made via
assigned parameters.
A position status parameter shows whether the position data reference of
a measuring system evaluated by the controller has been established.
In addition to the motor encoder an external (optional) encoder can be
available. Both encoders, in any combination of relative and absolute
measuring systems, can
• have position data reference to the axis independently of each other
(both encoders have different actual position values) - or -
• have position data reference to the axis dependent of each other (both
encoders have the same actual position values).
MPH-02, MPB-02, MPD-02
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
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