National Instruments VXI-MIO Series - Manual (Page 119)

Appendix C Common Questions
 National Instruments Corporation C-6 VXI-MIO Series User Manual
Gate Config, CTR Mode Config, and CTR Pulse Config advanced
level VIs to indicate which function the connected signal will
serve. Use the Route Signal VI to enable the PFI lines to output
internal signals.
Warning: If you enable a PFI line for output, do not connect any external signal
source to it; if you do, you can damage the module and the connected
equipment.
17. 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 module
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 Table 4-1. 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.