National Instruments 6008 - Manual (Page 19)

© National Instruments Corporation 19 NI USB-6008/6009 User Guide and Specifications
6. Select a static resistor value for your pull-up resistor that is greater than
or equal to the ideal resistance.
7. Re-connect the load circuit and the pull-up resistor.
I/O Protection
To protect the NI USB-6008/6009 against overvoltage, undervoltage, and
overcurrent conditions, as well as ESD events, you should avoid these fault
conditions by using the following guidelines:
• If you configure a DIO line as an output, do not connect it to any
external signal source, ground signal, or power supply.
• If you configure a 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.
National Instruments has several signal conditioning solutions for
digital applications requiring high current drive.
• If you configure a DIO line as an input, do not drive the line with
voltages outside of its normal operating range. The 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 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.
Static DIO
Each of the NI USB-6008/6009 DIO lines can be used as a static DI or DO
line. You can use static DIO lines to monitor or control digital signals. All
samples of static DI lines and updates of DO lines are software-timed.
Event Counter
You can configure PFI 0 as a source for a gated invertor counter input edge
count task. In this mode, falling-edge events are counted using a 32-bit
counter. For more information about event timing requirements, refer to the
Specifications section.