Appendix C
Common Questions
PCI-MIO E Series User Manual
C-6
©
National Instruments Corporation
18. What are the power-on states of the PFI and DIO lines on the I/O
connector?
At system power-on and reset, both the PFI and DIO lines are set to
high impedance by the hardware. This means that the board
circuitry is not actively driving the output either high or low.
However, these lines may have pull-up or pull-down resistors
connected to them as shown in Tables 4-1, 4-2, and 4-3. These
resistors weakly pull the output to either a logic high or logic low
state. For example, DIO(0) will be in the high impedance state after
power on, and Table 4-1 shows that there is a 50 k
Ω
pull-up
resistor. This pull-up resistor will set the DIO(0) pin to a logic high
when the output is in a high impedance state.