Chapter 4
Digital I/O
©
National Instruments Corporation
4-5
Analog Output Series User Manual
I/O Protection
To minimize the risk of damaging the DIO and PFI terminals of your
device, follow these guidelines.
•
If you configure a PFI or DIO line as an output, do not connect it to any
external signal source, ground signal, or power supply.
•
If you configure a PFI or DIO line as an output, understand the current
requirements of the load connected to these signals. Do not exceed the
specified current output limits of the DAQ device. NI has several signal
conditioning solutions for digital applications requiring high current
drive.
•
If you configure a PFI or DIO line as an input, do not drive the line with
voltages outside of its normal operating range. The PFI or DIO lines
have a smaller operating range than the AI signals.
•
Treat the DAQ device as you would treat any static sensitive device.
Always properly ground yourself and the equipment when handling
the DAQ device or connecting to it.
Power-On States
At system startup and reset, the hardware sets all PFI and DIO lines to
high-impedance inputs. The DAQ device does not drive the signal high or
low. Each line has a weak pull-up resistor connected to it, as described in
the specifications of your device.