Ni SMU Sourcing and Measurement against ground

[ergof]

Ok thank you for helping.

The only question that remains is, if the measured value will still be acceptable.

But that will be tested.

[Tomasz_Kowalczyk]

No problem.

Best wishes for this and next projects!

[janaf]

Hi,

The Hi-Low inputs of the SMU are floating versus chassis / ground. (The PXIe-4138 is rated to have up to 150V from Hi-Low to ground).

If you measure from Hi on the SMU to ground on another board, you will need to connect the SMU Low to Ground of the chassis / the other board. There's a ground female banana jack available on the SMU front panel. Then the voltage you set on the SMU will be relative to ground, which seems to be what you want.

Without grounding the Low of the SMU, it would be similar to attempting to measure from one pole (only) of a battery, to ground on the other board. Wouldn't work.

[ergof]

Hey Janaf,

thanks for the reply.

Yes I was aware that I had to ground the Low of the SMU, I just didn't know if it was safe. But the 150V number is giving me even more confidence that I won't have any problems with grounding it in the future. And as far as I am aware the Bananajack-ground on the front panel is the same as the chassis ground which is the same as the ground on the other board I am measuring against, so it's working fine already 🙂

Best regards