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Chapter 4
Signal Connections
The DPull pin controls the state of the input pins at power-up. Connecting DPull to +5 V or
leaving it unconnected configures all pins in all ports for 100 k
Ω
pull-ups. Connecting DPull to
ground configures the ports for 100 k
Ω
pull-downs.
PWM Features
The NI 7330 motion controller provides two pulse width modulation (PWM) outputs on the
digital I/O connector. The PWM outputs generate periodic waveforms whose period and duty
cycles can be independently controlled through software commands. The PWM is comparable
to a digital representation of an analog value because the duty cycle is directly proportional to
the desired output value. PWM outputs are typically used for transmitting an analog value
through an optocoupler. A simple lowpass filter turns a PWM signal back into its corresponding
analog value. If desired, you can use the PCLK input instead of the internal source as the clock
for the PWM generators.
RTSI Connector
The physical RTSI bus interface varies depending on the type of NI 7330 motion controller.
The NI PXI-7330 uses the PXI chassis backplane to connect to other RTSI-capable devices.
The NI PCI-7330 uses a ribbon cable to connect to other RTSI-capable PCI devices.
RTSI Signal Considerations
The NI 7330 motion controller allows you to use up to eight RTSI trigger lines as sources for
trigger inputs, or as destinations for breakpoint outputs and encoder signals. The RTSI trigger
lines can also serve as a generic digital I/O port. The RTSI star trigger line can be used only for
a trigger input. Breakpoint outputs are output-only signals that generate an active-high pulse of
200 ns duration, as shown in Figure 4-10.
Figure 4-10.
Breakpoint across RTSI
Encoder and Index signals are output-only signals across RTSI that are the digitally-filtered
versions of the raw signals coming into the controller. If you are using the RTSI bus for trigger
inputs or generic digital I/O, all signals are passed through unaltered.
200 n
s
