Finding the time delay between two signals

[SohamSaha]

In this code, I am sending a pulse into the DAQ using labview. The pulse triggers data input from a thermistor from another analog input.

I want to find the delay between the time of the positive edge for the switch, and the exact time the DAQ starts to take in signal from the thermistor.

I am attaching the code below.

Thanks.

[Kev_R]

Hi Soham_S

What modules are you using in your DAQ as the response time will depend on the hardware. In terms of measuring the time in the software have a look at this:

https://decibel.ni.com/content/docs/DOC-9811

Hope this helps

Kevin

[SohamSaha]

hardware: NI PXIe-1071 chassis, NI PXiE 6368, DAQ, SCB 68 connector.

Readings are taken from a thermistor.

For the 6368, the datasheet says that it uses a 100MHz timebase for faster triggering.

So to find the delay, I guess i neet a timer that can measure in nanosecond scale. Is there a way to modify the stopwatch/timers?

Thanks.

[Kev_R]

Hi

Thanks for the information. Could you please clarify what it is you are trying to measure?

Do you want to measure the time delay between the pulse being physically sent by the hardware and then being received by the analogue input module (i.e. the time delay on the hardware). If so this would be the slot-to-slot skew rate, which is the time for a signal to go from the controller to a slot. If you are using the 100MHz clock the skew time would be 100ps and for the 10MHz be 500ps

OR

Are you looking at the time from when the switch is pressed in your labVIEW code to then being received on the analogue input?

If you are only looking to benchmark the program that you have written in labVIEW, you can use the timing functions to do so. You can modify the timing functions within labVIEW to use mirco seconds with the functions in the FPGA toolkit.

[SohamSaha]

Thanks for the reply.

For the first delay (delay in the hardware), is it system defined, or can i somehow display it in a chart/numeric output?

For the second one, how do I modify the outputs to microseconds? I am not familiar with the FPGA toolkit.

Thanks.

[Kev_R · Accepted solution]

Hey,

Here's a link to some information about the Clock sources on the FPGA. 

http://digital.ni.com/public.nsf/allkb/94CE338CC80ACF008625791400516BAA?OpenDocument

Hope this helps