Chapter 5
Signal Connections
©
National Instruments Corporation
5-11
You can program breakpoints as
absolute
,
modulo
, or
relative
positions. Breakpoint outputs can be preset to a known state so that the
transition when the breakpoint occurs can be low to high, high to low,
or toggle.
The breakpoint outputs are driven by open-collector TTL buffers that
feature 64 mA sink current capability and built-in 3.3 k
Ω
pull-up
resistors to +5 V.
You can directly set and reset breakpoint outputs to use them as
general-purpose digital outputs.
Wiring Concerns
Caution
Keep trigger input, shutdown input, and breakpoint output signals and their
ground connections wired separately from the motor driver/amplifier signal and encoder
signal connections. Wiring these signals near each other can cause faulty operation.
Caution
Excessive input voltages can cause erroneous operation and/or component
failure.
Trigger Input, Shutdown Input, and Breakpoint
Output Circuits
Figures 5-5, 5-6, and 5-7 show a simplified schematic diagram of the
circuits used by the trigger inputs, shutdown inputs, and breakpoint outputs
for signal buffering.
Figure 5-5.
Trigger Input Circuit
74FCT244
1 k
Ω
1/8 W
From the external
connector
trigger pins
To the trigger
circuits
DGND
Vcc
3.3 k
Ω