© National Instruments
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4-5
NI 7330 User Manual and Specifications
Caution
To prevent damage to the NI 7340 or other motion hardware, use a resistor
that limits the current to a value below the maximum specifications of the controller
and other hardware.
Figure 4-2.
Step, Direction, and Inhibit Output Circuit
Limit and Home Inputs
The following signals control limit and home inputs:
•
Axis <1..4> Forward Limit Input
•
Axis <1..4> Home Input
•
Axis <1..4> Reverse Limit Input
These inputs are typically connected to limit switches located at physical ends of travel and/or
at a specific home position. Limit and home inputs can be software enabled or disabled at any
time. When enabled, an active transition on a limit or home input causes a full torque halt stop
of the associated motor axis. In addition, an active forward or reverse limit input impedes future
commanded motion in that direction for as long as the signal is active.
Note
By default, limit and home inputs are digitally filtered and must remain active
for at least 1 ms to be recognized. You can use MAX to disable digital filtering for
limit and home inputs. Active signals should remain active to prevent motion from
proceeding further into the limit. Pulsed limit signals stop motion, but they do not
prevent further motion in that direction if another move is started.
The input polarity of these signals is software programmable for active-low (inverting) or
active-high (non-inverting).
You can use software disabled limit and home inputs as general-purpose inputs. You can read
the status of these inputs at any time and set and change their polarity as required.
Limit and home inputs are a per-axis enhancement on the NI 7330 motion controller and are not
required for basic motion control. These inputs are part of a system solution for complete motion
control.
Caution
National Instruments recommends using limits for personal safety, as well
as to protect the motion system.
NI 7330
Step/Dir
Drive
Step+/Dir+
Step–/Dir–
+5 V
Optional
+5 V
3.3 k
Ω
