Chapter 5 Signal Connections
NI 7350 User Manual 5-6 ni.com
You can choose to drive the Step (CW) and Dir (CCW) outputs by
using either Totem Pole mode or Open Collector mode. In Totem Pole
mode, the output buffer can both sink and source current, which is
appropriate for most applications. In Open Collector mode, the output
buffer can only sink current. By default, Step (CW) and Dir (CCW)
outputs are set to Totem Pole mode.
Caution Do not connect these outputs to anything other than a +5 V circuit. The output
buffers will fail if subjected to voltages in excess of +5.5 V.
•Axis <1..8> Inhibit—Use the inhibit output signals to control the
enable/inhibit function of a servo amplifier or stepper drive. When
properly connected and configured, the inhibit function causes the
connected motor to be de-energized and its shaft turns freely.
You can set the inhibits to either Totem Pole or Open Collector mode.
In Totem Pole mode, the inhibits can both sink and source current.
In Open Collector mode, the output buffer can only sink current.
By default, inhibits are set to Open Collector mode.
Whereas the industry standard for inhibits is active low, these outputs
have programmable polarity and can be set to active high for increased
flexibility.
Inhibit output signals can be activated automatically upon a
Kill Motion command or any motion error that causes a kill motion
condition, such as a following-error trip.
You also can use the inhibit outputs of unused axes as general-purpose
outputs. However, for safety considerations, NationalInstruments
recommends that you use the inhibit outputs for all active axes.
Limit and Home Inputs
The following signals control limit and home inputs:
• Axis <1..8> Forward Limit Input
• Axis <1..8> Home Input
• Axis <1..8> Reverse Limit Input
These inputs are typically connected to limit switches located at physical
ends of travel and/or at a specific home position. You can use software to
enable and disable limit and home inputs at any time. When enabled, an
active transition on a limit or home input causes a full torque halt stop of
the associated 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.