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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 kΩ pull-ups. Connecting DPull to
ground configures the ports for 100 kΩ pull-downs.
PWM Features
The NI 7340 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 expected 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. You have the option to use the PCLK input instead of the internal source as the
clock for the PWM generators.
Note
These signals are configured in software and are in no way associated with
the PID servo control loop. Refer to the NI-Motion Help for more information.
RTSI Connector
The physical RTSI bus interface varies depending on the type of NI 7340 motion controller.
The PXI-7340 uses the PXI chassis backplane to connect to other RTSI-capable devices.
The PCI-7340 uses a ribbon cable to connect to other RTSI-capable PCI devices.
RTSI Signal Considerations
The NI 7340 motion controller 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.
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.
4-14 | ni.com
Figure 4-10. Breakpoint across RTSI
200 ns
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