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Chapter 5: MEI Software
We recommend choosing the slowest possible speed range that is adequate for your system. If an
axis is configured for servo, the speed selection should be:
Disable Output
.
Home
This selection configures whether the index pulse is required for the home input to be active.
Typically a rotary encoder has a single index pulse (per revolution). The index pulse can be used
with the home signal input to produce accurate homing to within one encoder count. Standard
boards have four possible types of homing:
Type Description
Home Only
Home input only (active high or active low)
Low Home and Index
Home input ANDed with index (active low home and active high
index)
Index Only
Index only (active high or active low)
High Home and Index
Home input ANDed with index (active high home and active high
index)
Note that the home/index setting affects the axes in groups of 4. For example, on a 4-axis board,
all the axes must be configured the same with respect to home/index. For more information, see
the section on home switch wiring.
Bipolar/Unipolar
This selection configures whether the analog output is unipolar (0 to +10 volts) or bipolar(-10
volts to +10 volts). When using analog servo motors, the output should be configured for bipolar
operation. When using steps, the output should be configured for unipolar operation.
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;
;
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Trouble Tip - Motors Turn Only One Direction:
Steppers
:
If a step motor turns only one direction, check the Configuration/Axis
Configuration window to be sure the axis is set for UNIPOLAR. The voltage-to-frequency-
converter only responds to positive voltages (unipolar) and will not output steps if the
voltage is negative (bipolar).
Servos
: If a servo motor turns only one direction, check the Configuration/Axis
configuration window to be sure the axis is set for BIPOLAR.
Feedback Device
This selection allows each axis to be configured for the type of feedback device used. The
choices are:
Selection
Device Type
Pin Location
Encoder
Incremental Encoder
Motor Signal Header
Analog
Unipolar LVDT
Analog Input Header
Parallel
Laser Interferometer
User I/O Headers
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