I am working on using the PCI-6034E with BNC-2110 to count the number of pulses within a given period of time. the input pulse has 5V amplitude and ~20ns width. However, for each pulse, there were some tail signals with around 1V amplitude. Will the till signals also be counted? If yes, is it possible to set the trigger voltage of the counter? Any help will be greatly appreciated.
Solved! Go to Solution.
The counters on a 6034E will need a TTL-compatible pulse. 1 V amplitude isn't likely to register as high. The specs say 0.0-0.8 is low, 2.0-5.0 is high. Anything in between is unknown.
No, digital trigger voltages aren't settable. This remains true for newer multifunction board families such as M-series and X-series.
Ideal hysteresis would that once signal crosses VIH it'll be registered as high until it crosses VIL.
This means, the rising edge is considered only if the signal crosses VIH 2.0V and it stays at high until it goes below VIL 0.8V.
If this is the case, your 1V tail will not register as another edge.
Thank you so much for the help. I just used a pulse generator to test it. And you are mostly correct. The threshold voltage of input high seems to be 1.7V on my board.
Actually, I am using the board to count signals from an SPCM-AQRH detector, which a signal photon detector. I used an oscilloscope and get the waveform of a pulse as shown below. There is a dip(-1V) after the main peak, and the difference between the dip and the tail signal is around 2V. I am not sure if the difference leads to a new count?
My electronics knowledge is pretty limited, but I think you might want to clean up that analog-looking pulse and make it look more digital before sending it to a 6034E counter. Something like a Schmitt trigger comes to mind.
This waveform is helpful and new information is that you have a -ve dip which is of concern to me and may damage the instrument.
The 1V peak in the tail should not register as High as the signal needs to cross VIH to register as HIGH. I would recommend using a diode across the signal (reverse biased) to clamp the negative segment.