Two pulse trains, one with delayed time

[b0giri01]

Hi,

I am trying to get two pulse trains using VI I attached here. I am able two produce two pulse trains but the amplitude of one is very low (0.2V) than expected. Can you please help me how to get same amplitude (5.0V) foe both pulse trains?

Regards,

Bharat

[Kevin_Price · Accepted solution]

Voltage outputs of counters aren't programmable, so it isn't the program.  The low voltage output is must be connected to a low input impedance circuit.  It's trying to pull more current from the counter than the counter can source, consequently the voltage is pulled way down.

On many devices, counter outputs are limited to a small # of mA.  It varies by device, but you can find it in the specs.

-Kevin P

[b0giri01]

Thanks Kevin,

Yes you are right but I found that the first pulse train from VI is always with high amplitude and 2nd with low whatever the counters chosen.

I am using PCI-6601.

[Kevin_Price]

What are your counter outputs physically wired to?  Did you change the physical wiring when configuring the task to use different counter #'s? 

Each counter has a distinct pin for its output signal.  Are you sure you've identified those pins correctly?

-Kevin P

[b0giri01]

Hi,

Counter's outputs are connected to oscilloscope directly (No other physical connection) and I didn't make any changes when configuring.

Regarding the pins for output, I checked it again. All are correct.

Thanks,

Bharat Giri

[b0giri01]

Hi,

I figured out the problem. It's due to the probe I used.

Thanks for your help.

Bharat

[Kevin_Price]

Just for the sake of future readers, was one probe / scope input at 50 ohms while the other was more like 1 Megaohm?

-Kevin P

[b0giri01]

Yes the ratio is same.

One of the probe was attenuated by 20 times.

Bharat