10-01-2012 10:01 AM
Can you "measure" a 1 KHZ,3VDC squarewave on a digital port of a PXI6723?? I trying to make sure the connection is good so I'm sending the (sq) waveform from the analog out thru a differential driver/receiver circuit and back into the DIO. I'm testing that the signal toggles at my freq. hi>lo>hi>lo>hi>lo...etc..
This maybe a diff post but..
The output of my differential driver is high impedance when its off and from what I understand when the 6723 sees a high impedance there is a pull up to ~3 volts so it would read a high if I looked at the port/channel. So my question is how could I tell when the signal to the diff circuit is low??
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10-01-2012 10:09 AM
@clint100 wrote:
Can you "measure" a 1 KHZ,3VDC squarewave on a digital port of a PXI6723?? I trying to make sure the connection is good so I'm sending the (sq) waveform from the analog out thru a differential driver/receiver circuit and back into the DIO. I'm testing that the signal toggles at my freq. hi>lo>hi>lo>hi>lo...etc..
You can't capture a waveform with the DIO. However, you could measure the freqeuncy with a counter on the same card.
clint100 wrote:
The output of my differential driver is high impedance when its off and from what I understand when the 6723 sees a high impedance there is a pull up to ~3 volts so it would read a high if I looked at the port/channel. So my question is how could I tell when the signal to the diff circuit is low??
Put in a pull down resistor. 10k should do it easily.
10-01-2012 10:30 AM
@crossrulz wrote:
You can't capture a waveform with the DIO. However, you could measure the freqeuncy with a counter on the same card.
Hi crossrulz,
capturing a digital waveform should be possible (as shown in example shipped with Labview Cont Read Dig Chan-Int Clk.vi).
Am I wrong?
Regards,
Marco
10-01-2012 10:48 AM
@MarcoMauri wrote:
@crossrulz wrote:
You can't capture a waveform with the DIO. However, you could measure the freqeuncy with a counter on the same card.
Hi crossrulz,
capturing a digital waveform should be possible (as shown in example shipped with Labview Cont Read Dig Chan-Int Clk.vi).
Am I wrong?
Regards,
Marco
If you read the spec of the PXI-6723, the DIO are only software timed. Therefore, the values are only read when the software tells the card to grab the current value. The timing will not be deterministic (which I think is kind of important). If you have hardware timed DIO, then a digital waveform could be captured.
10-02-2012 05:27 AM
You're exactly right. I tried it anyway and it read the line "when it wanted to". For example, I put in the squarewave and tried to read the line. After running my vi to read the digital line x amount of times sometime it would be high sometime it would be low, and not in any pattern.
Thanks