Measure time interval from analog output channel to digital input channel?

[ossoo]

Hi,

I have two signal. One is generated by DAQ AO channel; the other is acquired from DAQ DI channel.

AO: generate analog signal from 2.5V to 5V which is very steep transition

DI: Acquire signal which change from LOW to HIGH when AO voltage increase

I need to measure the time interval from AO rising edge (like 4V) to DI rising edge. Anybody can help me with this?

Thanks,

[Jim_S]

Hello,

After looking over your post, it looks like you want to acquire a Digital Input and generate a Analog Output. The Analog Output will be generating a signal between 2.5V and 5V. As for the Digital Input, it looks like you want to have it become high when the analog output reaches some voltage (like 4V). Does this mean that the Analog Output is looped back to the Digital Input? If this is the case, most of our DAQ cards' Digital inputs follow the TTL standard so it won't be possible a voltage to have it change states.

As for generating the Analog Output signal, have you looked at the DAQmx examples for generating a signal? With the DAQmx driver, there are examples for LabVIEW, C++, and .NET. If you are using LabVIEW, you can find the examples in the Example Finder located under Help » Find Examples.

I think I could help you better if you could explain your application in a little more detail. Could you provide the DAQ device you are using? Which version of the DAQmx driver you are using?

[johnsold]

Ossoo,

If you want to measure the time from the AO crossing a threshold until some digital signal changes state, set up an analog input task and record both the AO signal and the signal connected to the DI input.  Set the task for continuous input and start it before starting the AO.  Make the sampling rate high enough to get the timing resolution you need.

Lynn