Event counter free run when counter source is low

[diacon]

Hi all

I am trying to implement a simple event counter on a 6036 using NiDaq and VB6.  I have connected a quadrature encoder to the board phase a to counter0src pin. Configure the counter to be an event counter, ungated. Start the counter and all is ok except, when the counter0src pin is low, the counter will record random pulses. A voltmeter attached to the pin shows 0.0x volts, and no noticeable voltage glitchs.If I short the pin to ground, there are no false pulses recoreded.

Any thoughts? 

[dansch]

Hello diacon,

Thanks for the post! From your description, it sounds like you have some noise on the line which is causing the counter to incorrectly increment (perhaps using a scope to view the signal might give a better idea as to what is happening). Unfortunately, the E Series devices, such as the NI-6036E, do not contain digital filtering on the counter input lines, so this solution to the problem is only valid when using an M Series or 660x device. Thus, my suggestion would be to try and implement some kind of external filtering in order to remove these spikes or try to acquire the signal and process the values in software. Hope this helps,

[dansch]

I forgot to mention in my previous post that more information on this type of measurement, as well as further information regarding signal conditioning to alleviate the type of problem you are having, may be found in the Developer Zone tutorial document titled "Using Quadrature Encoders with E Series DAQ Boards." Hope this helps further,

[diacon · Accepted solution]

Dan

That is the information I was looking for, even if it wasn't what I wanted to hear!