How do I read a pulsed input on an SCB-68 counter channel?

Hello all, I have been searching through the DAQ help and this board
for a few hours now and I cannot find an answer that addresses what
should be a simple problem. Let's start with hardware and software: I
have a 6062E PCMCIA DAQmx card connected to a SCB-68 (E Series)
connector block. I am running Version 7.1.0.306 of Measurement Studio
for Visual Studio .NET and am coding in C#. So please, no LabView
answers.
I am trying to read the pulsed output of the Omega HHT-1501 Digital
Tachometer - it outputs a TTL LOW pulse every time the sensor is
triggered, I would like to read in these pulses and get the
frequency to determine RPMs. As far as I can tell I need to
connect the pulsed signal line to CTR0, which is PFI9/GPCTR0_GATE on
the connector block, pin #3. I have verified that the tachometer is
indeed pulsing correctly. I have used the DAQ Assistant to create a
DAQmx task to acquire the frequency of a digital signal using the 1
Counter Low Frequency Measurement method, input range is set from 1Hz
to 1KHz, starting edge is set to falling. For Task Timing the
Acquisition Mode is Continuous, Samples to Read = 100.
When I run the test I get no response. And it also seems that the
GPCTR0_GATE is always at +5V. I have tried just about every other
combination of inputs, including using CTR1 on GPCTR1_GATE, pin 41, all
with the same result - no signal read.
So what is the problem? Every post or help article I have read makes it
sound like plug and play to read the pulses but this is not the case -
does the counter gate need to be configured as an input in either
software or hardware? Am I supposed to have a signal set on the SOURCE,
and if so what? And what about my ground line from the pulse source? I
have tried attachign that to DGND, still no result, and if I attach the
pulse signal gnd to the GPCTR0_SOURCE it causes my tachometer to lock
up.
This thread
http://forums.ni.com/ni/board/message?board.id=170&message.id=34826&query.id=3937#M34826
seems to be very closely related to what I want to do but is as vague
as the help articles - it mentions using one of the two timebases as
the source input - what does this mean in terms of code/wiring?
Additionally in the NI-DAQmx help article under Device
Considerations->Counter Signal Connections->AO/E/S Series it says
"The count direction terminal must be tristated to use an external
signal. Reset the device to ensure the terminal is tristated" for edge
counting. A) Is this related? and B) how does one tristate by reset?
Power cycling the scb-68 has no apparent effect on anything.
I would appreciate any help on this matter, hopefully with as much
detail as possible since the help manuals seem to be mostly useless for
guiding one in performing any task.
Thanks!
J. Slater

Hi Shyam,
The major factor that would come into play with the signal having some noise is that the counter is expecting a TTL signal and the oscilloscope is measuring an analog input signal. If your signal floats above the TTL thresholds or does not rise/fall within the specifications, the behavior is not predictable and it can be measured as a high or low by the counter. An oscilloscope will measure the analog signal and you may be able to measure the frequency of the noise on your scope by analyzing a smaller timeframe of the signal.
What Is the Definition of a TTL (Transistor-Transistor Logic) Compatible Signal?
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/acb4bd7550c4374c86256bfb0067a4bd
Steve B

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"data/time reading into chart"
"In the attached file, I am trying to read the first column of data, and the next column is the value on the x-axis I want it plotted at. How do I read two columns of different data? I have looked in the books I have access to and the help within Labview but am still having trouble.
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