Just out of curiosity... But when you aquire the 40 channels in the main application, are any of the channels unwired / ungrounded? From my experience, acquiring ungrounded channels in the midst of properly wired channels will cause some type of saturation within the data acquisition card, or at least bogus noise in the signals. I'm not sure of the exact details, but it has to do with the ADC multiplexer that while switching, it doesn't have enough time to settle between channel reads that it makes it seem that the signals are fluctuating dramatically.
Try: 1) change your channel list to only contain channels necessary to your appliation, 2) if the channel list can't be changed then try grounding these open channels... By grounding them, this will diminish any bogus noise you'll get in your acquisition routine. Hopefully this helps. ------- Juan Carlos Flores ArchonWest Technologies telephone: 888.824.2320 mobile: 323.620.1548 http://www.archonwest.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Barry Brophy Sent: Monday, May 24, 2004 8:01 AM To: [EMAIL PROTECTED] Subject: Question to Info-LabVIEW Digest LabVIEW SCXI 1100 anomaly Dear all, I have run into a truly bizarre anomaly when reading from an SCXI 1100 card with labview 6.1. I have been using labview for over 4 years and have never seen anything like this. I wonder if anyone can help me. I have an application with many temperature readings. I have a dedicated SCXI 1102 card for most of these but I have not got enough channels so I have been using an SCXI 1100 card for the spillover. I noticed that the readings I was getting for this card were fluctuating a lot, much more than they did when I checked the signal in MAX. Also, I noticed that when I acquired from the 1100 card in a calibration routine elsewhere in my application, the signal wasn't fluctuating at all. The only difference between the calibration routine and the main application is that in the main application I am acquiring over 40 channels whereas in the calibration routine I am taking only 3 or 4 at a time. The code I am using is exactly the same in the two locations. only the number of channels being acquired is different. The signals from the 1100 are affected but the signals from the 1102 are fine in both routines. I have repeated this problem in two different locations. I have also noticed that it affects pressure signals on the SCXI 1100 as well. Can anyone offer me any advice on this? Regards, Barry Brophy
