Counter error

[NoelRK]

Hello.

I am using a NI-USB 6211 with Labview 8.2. I am using two counters, one for angular position and the other to count the number of z pulses from a rotary encoder. I am also measuring three analog signals with the board. When the analog signals are not plugged in the counter work properly, reading 1,2,3,4,..... but once the analog signals are connected the counter will count additional pulses, reading 1,4,7,9... I have tried shielding the analog wires but that seems to only make things worse. Does anyone know if I can somehow adjust threshold values for the counter or have any other suggestions to try and solve this problem. Thank you very much.

Noel

[PBear]

Hi Noel,

Try applying a digital pulse width filter to the inputs of each of your terminals (A, B, Z). This is available through a DAQmx Channel Property as shown below.

Are the analog signals being measured the same signals as the encoder pulses or are they from an different / independent source? If they're from the encoder I would recommend using some bias resistors to give built up charge a path to ground. But if they're completely different circuits then I'm not certain as to what would be causing this.

See if the below digital filter helps out.

Message Edited by PBear on 06-10-2008 11:11 AM

[NoelRK]

Thanks PBear. That's exactly what I did and it took care of the problem instantly.

Noel