I am using LabView Signal Express that came with my SCC-68. I have several voltage sensors connected:
RSE at Ai1 A+=Pin33, A-=Pin 67
RSE at Ai2 A+=Pin65, A-=Pin 32
Diff at Ai3 A+=Pin30, A-=Pin 63
Diff at Ai4 A+=Pin28, A-=Pin 61
RSE at Ai5 A+=Pin60, A-=Pin 27
My problem is the Ai3 signal. I am trying to read a mV representation of the current of a motor. I hooked up a Fluke clamp current meter which outputs 1mV per 1 Amp sensed. I have another multimeter connected directly to the same points where the signal is connected to the SCC-68. On the meter I read 0 mV and when I increase motor current up to 11 Amps ... I read ~11mV. HOWEVER, I read around 15mV on the Ai3 input the entire time. All other inputs are working fine. I even tried to move this input to another input (Ai6) but got the same results.
The only thing I can think of is that all the other inputs are referenced in some way to one power supply where the current one runs off it's own battery. However I tried to tie the return side to the same ground to make it a common reference but it didn't fix the problem. I also experimented with changing it to a RSE and so forth.
Any ideas? I am truly new to this because we just got this equipment.
So to review:
- getting incorrect reading from 1 of 5 signals
- reading voltage directly at connection to SCC-68 with a multimeter and not reading the same as the SCC-68 is
- that one is a meter that runs off it's own 9v battery
- all others run off a common 5v power supply
HELP please!
