measuring a high current

[satriany]

Hello Every body,

i try to measure a high current in a very short period of time with a
DAQ-Assistent but i have a problem with  triggering the signal to be 
able to measure this high current about( 2KA or 3 KA) in microsendes.
i use a resistance to measure the current as voltage and i connected 
the wire to analog input Dev1/ai0
my device is PXI-6259
i have labview 7.1

i tested this VI with a function generator connected to the analog input 
and it works but with my signal which is very short  ( in microsendes ) it didn't trigger

could you please support me with the best way to prgramm this 
application 
is it right what i did in this DAQ or there is another way to achieve 
this function ? 

 thank you very much
Satriany

[gwd]

some thoughts

- your vi doesn't appear to have any trigger configured

- the PXI-6259 has a 1.25 Ms/s sampling rate, which might be marginal for your signal (depending on whether you're talking about many microseconds or just a few)

 

[satriany]

Hello gwd,

thank you for replaying.
- could you tell me what is the best trigger configuration to let my VI works or there is another sutiable VI to do this function
- about the time in which the current flows ,  it is actually varialbe  because sometimes it is 30µs and other times it is about 100µs or more
 it just depends on the time of switching on the semiconductor which i use.

the goal of measuring the current  is  to  compare  the actual value of the current  with  a certain set value
  and when the actual value reachs the set value the output signal should be switched off.
so for me firstly is to be able to measure the actual value of the current.  

thank you very much
Satriany

[gwd]

I am not completely clear on your measurement (I intially thought it was a storage time measurement) but I assume there is a pulse generator somewhere with a trigger output. I would start with one of the shipping examples, either of

Acq&Graph Voltage-Int Clk-Dig Start.vi

Acq&Graph Voltage-Int Clk-Analog Start w Hyst.vi

depending on whether you want to use analog or digital trigger. Note that the trigger cannot go to another of the analog inputs because there is only one A/D in your device.

Both of these work with your board (according to the documentation).