Output turning off after setting voltage

[balanunni]

I am using labVIEW to do the following on 2401SMU.
1.Initialize
2.output enable
3.select source function as voltage, set range, set amplitude.
As soon as labVIEW sends select source command ":SOUR:FUNC VOLT" the output turns off. But the strange thing is this happens only in this particular sequence. If after the above 3 steps i again enable the output and set voltage again using the same set of commands, output stays ON. Can anybody please help me in solving this? This is part of an automation, so at any instant the output is not supposed to turn off until and unless the user wants it to.

[Dave W]

Hi balanunni,

Are you able to share the VI you wrote so we can try it out?

The :SOUR:FUNC VOLT command sets the source function to voltage. If the source function was configured as a current source prior to sending this command, the output will turn off when this command is set. The output will turn off whenever the source function changes.

The source will also turn off automatically at the end of the Source-Delay-Measure cycle if Auto Output-Off (also known as Source Auto Clear) is enabled. This can be turned on/off using the :SOURce:CLEar:AUTO command.

[balanunni]

Hi Dave,
I have attached the LabVIEW VI.
I think the problem is, as you have pointed out, the change in source function. Manually I tried the same on the instrument. When source changes the output is turning OFF. I am doing a reset before turning ON the instrument, which makes source function as 'current'. So in the next step when i choose voltage source, it turns OFF. May i know why this happens, is this a requirement for safety?
Thanks.

[Dave W]

Hi balanunni,

The output turning off when the source function changes is just part of how the 2400 operates. I can't say for certain, but this may be an architectural limitation of the 2400 and turning the output off is required to avoid exposing the device under test to potentially damaging glitches. The 2600B Series SMUs do not have this limitation and the source function can be changed without turning the output off.