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© National Instruments Corporation 6-1 NI 6238/6239 User Manual
6
Digital Input and Output
NI 6238/6239 devices have six static digital input lines, P0.<0..5>. These
lines also can be used as PFI inputs.
In addition, the NI 6238/6239 devices have four static digital output lines,
P1.<0..3>. These lines also can be used as PFI output.
The voltage input and output levels and the current drive level of the DI and
DO lines are listed in the NI 6238/6239 Specifications. Refer to Chapter 8,
PFI, for more information on PFI inputs and outputs.
I/O Protection
Each DI, DO, and PFI signal is protected against overvoltage and
undervoltage conditions as well as ESD events on NI 6238/6239 devices.
Consult the device specifications for details. However, you should avoid
these fault conditions by following these guidelines.
•Do not connect any digital output line to any external signal source,
ground signal, or power supply.
• Understand the current requirements of the load connected to the
digital output lines. Do not exceed the specified current output limits
of the digital outputs. NI has several signal conditioning solutions for
digital applications requiring high current drive.
•Do not drive the digital input lines with voltages or current outside of
its normal operating range.
• 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.
Programmable Power-Up States
By default, the digital output lines (P1.<0..3>/PFI <6..9>) are set to 0. They
can be programmed to power up as 0 or 1.
Refer to the NI-DAQmx Help or the LabVIEW 8.x Help for more
information about setting power-up states in NI-DAQmx or MAX.