Chapter5 SignalConnections
©NationalInstruments Corporation 5-5 7344/7334Hardware User Manual
•Axis<1..4> Inhibit—Use the inhibit output si gnals to control the
enable/inhibitfunction of a servo amplifier or stepper driver. When
properly connected and configured,the inhibit f unction causes the
connected motort o be de-energizedand its shaft turns freely. These
open-collector inhibit signals feature 64 mA current sink capability
with built-in 3.3 kΩpull-up resistors to +5 V,and can directly drive
most driver/amplifierinhibit input circuits.
Whilethe industry standard for inhibits is active-low (inverting), these
outputs haveprogrammable polarity and can be set to active-high
(non-inverting)for increased flexibility and unique drive
compatibility.
Inhibit output signals can be activatedautomatically upon a Kill
Motion command or any motion error that causes a kill motion
condition (forexample, following error trip). You can also directly
control the inhibit output signals to enable or disable a driveror
amplifier.
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
Thesei nputs aret ypically connected to limit switches located at physical
endsof travel and/or at a specific home position. Limit and home inputs can
be softwareenabled and disabled at any time. When enabled, an active
transition on a limit or home input causes a full torque halt stop of the
associatedmotor axis. In addition, an active forward or reverse limit input
impedes future commanded motion in that direction for as long as the
signalis active.
Note Limitand home inputs are digitally filtered and must remain active for at least 1 ms
to be recognized. Activesignals should remain active to prevent motion from proceeding
further into the limit. Pulsed limit signals stop motion, but they do not preventfurther
motion in that direction if another move is started.
Theinput polarity of these signals is software program mable for active-low
(inverting)or active-high (non-inverting).