Bosch Rexroth IndraDrive MPH-02 Functional Description page 188

5-64
Motor, Mechanical Axis System, Measuring Systems
Controlling the Dimensioning
Regarding Absolute Encoder
Evaluation
Actual Position Value of
Encoders To Be Evaluated in
Absolute Form After Switching
Absolute evaluation
possible?
Motor External
encoder encoder
yes yes
Note: If absolute evaluation of an encoder is possible but not
desired, the absolute evaluation can be switched off by setting
the respective bit in the S-0-0277 or S-0-0115 parameters!
The encoder can then only be evaluated in relative form!
To dimension absolute encoders it is necessary to check by the way of
calculation whether the intended travel range of the axis, considering all
mechanical transfer elements, can be displayed within the absolute
encoder range.
The following condition must be fulfilled:
• rotary encoders: Travel range of the axis requires less encoder
revolutions than preset in the absolute encoder range!
• linear encoders: Travel range of the axis is smaller than preset in the
absolute encoder range!
The actual position value of an absolute measuring system must be
adjusted to the mechanical axis system once at initial commissioning.
On
Note: The adjustment is made by determining an actual position
value, related to the axis zero point, given a defined axis
position
measuring). Thereby the offset between the actual position
value that first is encoder-related and the required axis-related
actual position value is internally determined and permanently
stored! The respective encoder then is "in reference".
At first the actual position value is only encoder-related. If the drive, for
example, is only equipped with one measuring system (motor encoder to
be evaluated in absolute form) the controller sets the actual position value
to
• P-0-0019, Initial position value
The initial position value can be determined by the user!
If the drive, apart from the motor encoder, is equipped with an external
encoder and at least one encoder can be evaluated in absolute form, the
following actual position values, depending on the reference status of the
encoder, are resulting after switching on:
Actual position values
when switching on
Motor External
encoder encoder
(S-0-0051) (S-0-0053)
P-0-0019 P-0-0019
absolute absolute
value motor value motor
encoder encoder
absolute absolute
value ext. value ext.
encoder encoder
absolute absolute
value motor value ext.
encoder encoder
(P-0-0012, C0300 Command
Notes on the commissioning status
Initial commissioning not yet carried out,
none of the encoders has "reference".
During the initial commissioning only the
motor encoder was set "in reference".
During the initial commissioning only the
external encoder was set "in reference".
During the initial commissioning both
encoders were set "in reference".
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
MPH-02, MPB-02, MPD-02
Set absolute
Current
position
status
(S-0-0403,
bit ..2,1,0)
0b ... 000
0b ... 01x
0b ... 10x
0b ... 111