Re : Period measurements using counter on 6211

[jnallen]

Hi,

I want to use the Period Measurement using one counter on the USB 6211 to measure pendulum oscillations.I have a photogate (laser diode and photodetector) which I want to use to detect oscillations.

If I connect a signal generator to the ctr0 pin (instead of the photodetector), my VI reads the period of the pulses.

When I connect my photodetector to the same pin, it does not read any values. Can this counter be used in this fashion? Where am I going wrong?

Regards,

James.

[JB]

Please provide the link to the datasheet of the photogate.

• How do you wire its output ?
• Does it generate a TTL level compatible signal ?

[Ben.h]

Hi James,

The reason you not getting a value through the counter input of your USB 6211 could be that the voltage from the photodetector is analogue and not digital or not meeting the minimum pulse width requirements of the device.

The data sheet for the photodetector would help us find out how an oscillation of your pendulum is outputted as a signal, then we can proceed from there.

Ben hartrick

Applications Engineer

National Instruments

[jnallen]

Hi guys,

Thanks for your replies. The problem was with the output from the photodetector. I have had this output signal conditioned to give me a high and a low entering ctr0. It working as it should now.