Programming Ultrasonic sensor HC-SR04

[kdm7]

Hi Gerd,

I am using the PFI0  for trigger and I am designing a counter. ( I am using a digital input (of usb6008) (echo pin connected to it) and reading the boolean value. For each true, the counter is incremented.

I've attached my counter part

[kdm7]

Here is my vi

What's wrong?

Please help!

[GerdW]

Hi kdm,

I don't know what's wrong. You don't tell us, what's not working as expected…

- You read your DI once each 14ms (due to AI task set to 1000S/s and 14 Samples/read).

- You increment your counter on each edge of the digital input - that's different to your text "increment on TRUE".

- You do a lot of stuff more complicated then needed to…

[kdm7]

Hi Gerd,

What does this error mean..

Possible reason(s):

Requested value is not a supported value for this property. The property value may be invalid because it conflicts with another property.

Property: SampTimingType
Requested Value: Change Detection
You Can Select: On Demand

No, I think I read my samples for every 140us  (due to AI task set to 100000S/s and 14 Samples/read). ..as minimum width of the pulse of echo is 150us.

[GerdW]

Hi kdm,

the USB6008 is NOT ABLE to read a AI with 1MS/s. AGAIN: read the specs of the USB6008!

You alse mis-wired your settings: You did wire a 1000 to rate input of DAQmxTiming and a 100,000 to sample size input. Please read the context help for that function…

That error message is quite clear: you wired a property setting that is not supported by your hardware!

Conclusion: READ THE SPECS!

[kdm7]

Hi Gerd,

Okay

I think my trigger is not generating 10us. How to check that?

[kdm7]

For a 10us trigger, what should the high time and low time be?

[GerdW]

Hi kdm,

you can check your outputs using a scope…

AGAIN: Read the specs of the USB6008. It is not able to prduce 10µs pulses!

[kdm7]

Hi Gerd,

The specs says that the minimum input pulse width is 100ns. I could not find any details about the minimum __output__ pulse width.

[Dennis_Knutson]

You aren't making any sense. There is a spec for the trigger input to the basic event counter. There is no such thing as a trigger output. The only output you have is the digital I/O and that is software timed. The minimum pulse it's going be in milliseconds with considerable jitter. You've been told numerous times that the device is not capable of generating a 10us pulse.