Operational Considerations
3.3
Reference Switch
All stage versions are equipped with a direction-sensing Hall-effect reference
switch, which is located at about the midpoint of the travel range. This sensor
provides a TTL signal indicating whether the positioner is to the positive or
negative side of a fixed point. The rising or falling edge of this signal can be
used to indicate a known reference position within 0.5 µm accuracy
(depending on the controller). The difference in the reference point when
approached from the positive or the negative side is about 0.2 mm to 0.4 mm.
See the controller User Manual and/or associated software manuals for the
commands which make use of the reference signal.
3.4
Rotary Encoder
M-403.xDG and M-403.xPD are equipped with DC motors with a
shaft-mounted position encoder. It provides highly accurate signals
whenever the position changes by a known, small amount. By monitoring the
encoder pulses, called
counts,
the controller can keep track of the relative
motion of the stage. To discover the absolute position, it is necessary to drive
the stage to a limit or reference switch. Most controllers have commands to
automate this procedure, which is called
referencing.
3.5
Motor Controllers
M-403-series micropositioners can be connected to the same motor
controllers as other micropositioners from PI.
DC motor controllers from PI can control both analog and ActiveDrive™
(PWM) motor versions. The required operating mode is set
automatically—depending on the controller model, either directly when the
controller is powered up, or when the user chooses the connected positioner
type in the control software.
If networking several positioners, you have to keep in mind that stepper
motor devices can only be networked with other stepper-motor devices.
This manual includes a list of suitable controllers.
3.6
Host PC
Most controllers from PI are in turn controlled by a host PC provided by the
user.
The controller is either installed directly in the PC (e.g. C-843 PCI board) or
connected to it over a communications interface. See the controller User
Manual for details.
www.pi.ws
M-403 MP 73E Release 2.0.1 Page
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