Having problems to setup 3458A to read digital voltage from waveform

[Ruslan72]

I am trying to use 3458A to read digital voltage from waveform. I need to take one reading ever ytime external clocks triggers it. I modefied the sample application from NI to configure DVM to dake DC measurements. But it seems it gives me an error when it tries to read reading from memory. It looks like it does not know that DVM is done, so it times out.  I set my arm triger to single, triger event single and sample event to external, but I am kind of confuse about last two.

Here what I am tryin to do: I am measuring ramp waveform, and I sending 500Hz clock to external triger of DVM. I need to take one reading every 1/500 and convert it to voltage. Ramp is from 0 to 3.3V.

I do not understand what inputs needs for sampling rate and number of measurements.

If any body has VI that can work, please save it in 6.1 format.

Thank you.  

[Dennis_Knutson]

I'm not sure you are approaching this the correct way. If you want to take a sample every 2 msec, the sampling rate should be set to 2e-3 and when you send a single trigger pulse, it will start the acquisition and return however many samples you wish to acquire. If you set the number of samples to 1000, you will get 2 seconds worth of data (number of samples times sample rate). If the ramp starts at the same time as the trigger, then you should be able to acquire the entire waveform. Trying to trigger the meter every 2 msec, do an acquisition, and transfer the data, is probably outside the specs of the meter. Your manual should tell you have fast it can be retriggered. Second, once a trigger has been generated, you should use the HP 3458A Utility Wait for STB before trying to read the data. The status byte read will tell you that the acquisition has been completed and data is available.

[Ruslan72]

Thank you.

Can you help me to set settings for triger arm, triger event and sample event.

I was trying to use single for triger arm, since I need to arm it only once.

For triger event I used single too, and for sample event I used external.

[Dennis_Knutson]

I'd be guessing since I don't have the instrument or manual and the only time I used this instrument was a very long time ago. The external arm event requires that a low-going TTL transition be detected at the ext trigger input and then it will be armed. The single arms once with receipt of single and then is disabled. You might want to try auto which always arms.