Hi all,
Forgive me if the question is stupid. I am trying to make a labview program to measure MOS transistor curves. As you know, I need to measure both the gate current and drain current. 2 2400 sourcemeters are available to use. I have connected the two instruments via separate GPIB buses by NI.
I'm having a hard to figuring out how to synchronize the data aquisition. I have read some discussions in this forum. Apparently an external triggering will be needed to do the job. My question is, do I need some hardware/cables for external triggering or just need to set it up in the labview program?
I appreciate your time and help.
Bo
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external triggering with 2 sourcemeters
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Andrea C
- Keithley Applications
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Re: external triggering with 2 sourcemeters
Bo,
Totally depends on how the software is implemented.
Take the case of an IDVG transfer curve. You want to put a bias voltage on the drain and sweep the voltage on the gate. For each gate value you want to measure the drain current. Optionally measure the gate current too.
You could apply the drain voltage and then just use a for/next loop to apply the gate voltage, measure current, next gate voltage in the loop, etc. In this case, no hardware trigger is needed. This software approach is fairly easy.
You could get a trigger link cable (8501-1) and connect the triggers together. In this case you would program each 2400 to do a sweep. The drain would be using a list sweep of the same voltage value again and again. The gate would use a true sweep. The trigger could be used to coordinate the sweeps so that the gate sweep does not advance until the current measurements are completed. The drain would wait for a trigger to know when to measure. The drain would output a trigger when measure is done. The gate uses this to know when to source next value in the sweep. Of course, for the very first values to get the sweeps started, use of trigger bypass would be used for the gate.
The benefit of this approach would be optimal test time. If you had a production test high throughput requirement, use triggering. Otherwise, it might not be worth the complexity of the setup.
Andrea
Totally depends on how the software is implemented.
Take the case of an IDVG transfer curve. You want to put a bias voltage on the drain and sweep the voltage on the gate. For each gate value you want to measure the drain current. Optionally measure the gate current too.
You could apply the drain voltage and then just use a for/next loop to apply the gate voltage, measure current, next gate voltage in the loop, etc. In this case, no hardware trigger is needed. This software approach is fairly easy.
You could get a trigger link cable (8501-1) and connect the triggers together. In this case you would program each 2400 to do a sweep. The drain would be using a list sweep of the same voltage value again and again. The gate would use a true sweep. The trigger could be used to coordinate the sweeps so that the gate sweep does not advance until the current measurements are completed. The drain would wait for a trigger to know when to measure. The drain would output a trigger when measure is done. The gate uses this to know when to source next value in the sweep. Of course, for the very first values to get the sweeps started, use of trigger bypass would be used for the gate.
The benefit of this approach would be optimal test time. If you had a production test high throughput requirement, use triggering. Otherwise, it might not be worth the complexity of the setup.
Andrea
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