8-28
Drive Functions
MPH-02, MPB-02, MPD-02
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
Functional Description
By starting the "set absolute measuring" command the previous actual
position value of an encoder at a reference position of the axis is set to a
new value. The reference position corresponds to the current axis position
at the start of the command.
The new actual position value at the reference position after "set absolute
measuring" is the value of parameter
•
S-0-0052, Reference distance 1
(for motor encoder)
- or -
•
S-0-0054, Reference distance 2
(for external encoder).
motor encoder:
S-0-0051
new
= S-0-0052
external encoder: S-0-0053
new
= S-0-0054
S-0-0051:
actual position value 1
S-0-0052:
reference distance 1
S-0-0053:
actual position value 2
S-0-0054:
reference distance 2
Fig. 8-21:
Actual position values after "set absolute measuring"
If several encoders to be evaluated in absolute form are connected to the
controller, it is possible to select, via
P-0-0612, Control word for setting
absolute measuring
, the encoder for which the "set absolute measuring"
command is to take effect.
In order that an encoder to be evaluated in absolute form maintains the
position data reference to the axis after "set absolute measuring", the
absolute encoder offset is stored in the encoder data memory
(P-0-1002/P-0-1012) and in the parameter memory (P-0-0177/P-0-0178).
Note:
Storing the absolute encoder offset in the encoder data
memory and in the parameter memory allows recognizing
whether the absolute encoder that was homed was replaced!
If the "set absolute measuring" command is cyclically used in the
operational sequence (possibly in conjunction with external setting of
reference position), it makes sense to store the absolute encoder offset
temporarily only. This kind of storage does not affect the service life of the
encoder data memory and the parameter memory. In parameter
S-0-0269, Parameter buffer mode
it is possible to select whether
parameter values are to be stored permanently or temporarily.
Note:
When the absolute encoder offset is stored temporarily the
encoder loses the position data reference to the axis when the
controller is switched off or when the parameter mode (P2) is
activated.
The "set absolute measuring" command can be activated in the following
operating states:
•
drive is ready for operation, but not active ("AB")
•
drive is active in position control ("AF")
•
drive is active and in "Drive Halt" ("AH")
When the "set absolute measuring" command is started, the reference of
the selected encoder is cleared first (S-0-0403).
Reference Position
Selecting the Absolute Encoder
to be Homed
Storing the Absolute Encoder
Offset
Parameter Buffer Mode
Possible Operating States
Before "Set absolute Measuring"
Sequence of "Set Absolute
Measuring"...
Courtesy
of
CMA/Flodyne/Hydradyne
▪
Motion
Control
▪
Hydraulic
▪
Pneumatic
▪
Electrical
▪
Mechanical
▪
(800)
426-5480
▪
www.cmafh.com
