Chapter 4
Signal Connections
©
National Instruments Corporation
4-15
Breakpoint (Position Compare) Output Circuit
The PCI-7390 provides four optically isolated breakpoint or position
compare outputs. Figure 4-10 shows a simplified schematic diagram of the
circuit used by the breakpoint outputs. The breakpoint outputs are driven
by TTL buffers that feature 24 mA sink and source current capability and
built in 20 k
Ω
pull-up resistors to +5 V.
You can directly set and reset breakpoint outputs to use them as
general-purpose digital outputs.
Figure 4-10.
Breakpoint (Position Compare) Output Circuit
General-Purpose Inputs
The PCI-7390 provides eight optically isolated sinking or sourcing
general-purpose inputs.
•
Axis <1..4> Drive (Servo) Ready
—When enabled in software, the
drive ready input can be connected to the drive ready output or servo
ready output of the drive. It is a drive status signal indicating that the
drive is ready or enabled.
•
Shutdown Input
—When enabled in software, the shutdown input
signal can be used to kill all motion by asserting the controller inhibits,
stopping any stepper pulse generation, and returning to the default I/O
state. The shutdown input is typically connected to an emergency stop
switch if it is present in the system.
The input active state of these signals is software programmable for
active open or active closed. You can configure any of the eight
general-purpose inputs as the shutdown input. The controller must be
reset to clear the shutdown state.
High Speed Optocoupler
V
cc
PCI-7390
Iso +5 V
Isolated Ground
Breakpoint Output
22 k
Ω
ABT 126
TTL Buffer
