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Appendix B
Common Questions
©
National Instruments Corporation
B-3
6711/6713/6715 User Manual
The DAQ-STC also makes buffered operations possible, such as direct
up/down control, single pulse or pulse train generation, equivalent time
sampling, buffered period, and buffered semiperiod measurement.
I’m using one of the general-purpose counter/timers on my 671X
device, but I do not see the counter/timer output on the I/O connector.
What am I doing wrong?
If you are using the NI-DAQ language interface or LabWindows/CVI, you
must configure the output line to output the signal to the I/O connector. Use
the
Select_Signal
call in NI-DAQ to configure the output line. By
default, all timing I/O lines except EXTSTROBE* are tri-stated.
What are the PFIs and how do I configure these lines?
PFIs are Programmable Function Inputs. These lines serve as connections
to virtually all internal timing signals.
If you are using the NI-DAQ language interface or LabWindows/CVI, use
the
Select_Signal
function to route internal signals to the I/O connector,
route external signals to internal timing sources, or tie internal timing
signals together.
If you are using NI-DAQ with LabVIEW and you want to connect external
signal sources to the PFI lines, you can use AO Clock Config, AO Trigger
and 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.
Caution
If you enable a PFI line for output, do not connect any external signal source to
it; if you do, you can damage the device, the computer, and the connected equipment.
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 device 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 4-2. 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 4-2 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.
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