signal express measuring

[azenteno]

Hi,

I am trying to do this measuring using LabVIEW SignalExpress as software in a PCB which has conectors that fit with SHC68-68

Module                                cable                          pcb

PXIe 1078 (PXIe 6361) ----- SHC68-68-EPM   ------ PCB

however I am not obtaining the real voltages.... I made the acquisition via signal express and later I made a measuring with an multimeter and the results are different values.....

Doing another test like that I am obtaining the real voltages

Module                                     cable                          module

PXIe 1078 (PXIe 6361) ----- SHC68-68-EPM   ------ SCB 68 ---------- external power source

why I am not obtaining the real voltages in case one? is it a question of callibration? set up? or maybe it is not possible to do a direct measuring?

I really will appreciate any advice or comment about this problem.

[Dennis_Knutson]

You should post your question to the SignalExpress board. Not many people here use it but offhand, I'd say you have a configuration problem. You have not provided any details on actual connections or task setup (i.e. differential, RSE, etc.). Provide that when you repost.

[Alhern]

Hi azenteno.

It sounds more like a wiring or grounding issue. The SCB 68 is a shielded connector block, so there might be a chance that the PCB either has a ground loop or has some connection errors. Is there a chance you could provide me with a connection schematic or the PCB´s schematic?