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I have two discontinous input TTL

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signals, I want to measure the arrival time of each pulse at the two inputs. How do I trigger the two pulses using Labview on E-6062 card? How do I direct the two signals to two different triggers and output the time each time a pulse arrives at the input?
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signals, I want to measure the arrival time of each pulse at the two inputs. How do I trigger the two pulses using Labview on E-6062 card? How do I direct the two signals to two different triggers and output the time each time a pulse arrives at the input?Boualem,
You will want to use a buffered counter operation to accomplish your goal. I am not clear if you want the time between each pulse that comes in (on a single pulse) or the absolute time of each edge, so I will explain both of these methods.
If you want the absolute time of each edge, you will use Buffered Event Counting. You will connect your TTL signal to the gate of the counter. Each time a signal comes in on the gate, the counter will latch its current value into a buffer. When you read the buffer you will be able to see the time when the pulses came into the DAQ card. By knowing the timebase of the source (100k or 20M if using an internal source) you know the time of each pulse. Note the first number in the buffer is the number of counter between the armin
g of the counter and the first gate edge, so you may want to ignore this value.
If you need to know the time between each pulse, you should use Buffered Period Measurement. Connect your TTL signal to the counter Gate. Each time there is a pulse on the gate, the counter latches the current value and then resets the count, so that you get the number of counts between rising (or falling) edges.
There are examples that ship with NI-DAQ (install support for LabVIEW) that show how to do both of these. See \examples\daq\counter\DAQ-STC.llb for the counter examples for E-Series boards. These examples are setup to work with one counters, you will need to duplicate the code to work with multiple counters. There is an example in NI�s Developers Zone that shows how to configure multiple counters on NI-TIO and DAQ-STC based boards. www.ni.com/zone -> then search on �multiple counters.� The first hit (Simultaneous Buffered-Event�) will be the one you want to look at.

Nick Wil
son
Applications Engineering
National Instruments
www.ni.con/ask
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