Hi Barry, I suspect you have a mix of pressure and temperature channels connected to the SCXI 1100.
Note that the 1100 and the 1102 are slightly different on the inside. The 1100 has only one amplifier (and correspondingly, only 1 gain value) that is multiplexed to all the input channels. So it is not recommended to choose channels that have different gains on them connected to it. Temperature channels will use 1000 gain (or something high), whereas any other channel will need a lot less gain, so the lowest possible gain value will be applied to all the channels which is why they may seem like they are "noisy" or jumping around. In NI-MAX when you look at that individual channel, the max gain will be applied and the thermocouples will look solid and reliable. The gain selection is transparent to the user and is based on the channel range that you specify on the virtual channel. The 1102 actually has a separate amplifier for each of the 32 input channels and you can set individual gains for each of them (again transparent to the user, based on the channel range). Note that it does not have as high a gain as the 1100 module. So move all temperature channels to the 1100, and other channels to the 1102. This is the recommended solution as the 1100 is designed for thermocouple channels which require high gain. Or move channels that require the same gain to the 1100, and rest of the channels to the 1102. That should fix it. Neville Dholoo Cellex Power Products, Inc. Richmond BC Canada ---------------------------------------------------------------------- Subject: Question to Info-LabVIEW Digest From: "Barry Brophy" <[EMAIL PROTECTED]> Date: Mon, 24 May 2004 16:01:11 +0100 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 ---------------------------------------------------------------------- Subject: RE: Question to Info-LabVIEW Digest From: "Juan Carlos Flores" <[EMAIL PROTECTED]> Date: Mon, 24 May 2004 08:48:27 -0700 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 ---------------------------------------------------------------------- Subject: DAQmx pretrigger From: "Seifert, George" <[EMAIL PROTECTED]> Date: Mon, 24 May 2004 14:59:23 -0500 I'm trying to convert two channels on a PCI-MIO-16E-1 board using DAQmx and LV7.0. I need to get some of the pretrigger samples. The best I can figure out from the documentation is that if I want to get pretrigger samples I can only convert one channel? Can that be right? George Medtronic Neurological, Inc., Sullivan Lake MS: N240 800 53rd Avenue NE Columbia Heights, MN 55421-1200 (763) 514-7264 [EMAIL PROTECTED] ---------------------------------------------------------------------- Subject: Re: Slow Printing From: "Frank" <[EMAIL PROTECTED]> Date: Mon, 24 May 2004 13:58:38 -0700 Does the slow printing problem go away with an upgrade to LV 7 or 7.1 and win XP? I am trying to make the case for upgrading. Changing from the windows platform is not an option but an upgrade to LV 7 and XP may be. I assumed (yes I know <g>) that all Windows had some kind of print spooler that would spool a print job to disk or memory and then send it to the printer in the background. I have seen the slow printing under labview several times (version 6.x) with NT-4 and Win 98. Am I doing something wrong in my programming? My strategy is to check the Automatically print panel every time vi completes execution box and then run the vi. I want to be lazy and not have to change a lot of code. It seems that with all that NI does to make programming easy, they would have handled this in some way. If that is not an option then I will try the suggestion from Dan. Frank Original message: >I have a system with Labview 6.0 on NT-4 that prints a 1 page report. This >is done by selecting Automatically print panel every time vi completes >execution. This vi takes about 30 seconds to complete, probably due to a >slow connection to the network printer. If the Automaticaly print panel >checkbox is not checked the vi runs in about a second so it seems that the >printing is the problem. Has anyone else seen this slow printing? Is there >any way to have labview spool to a file and then print the file or some >other way to speed up printing. > >I am trying to avoid allowing the print routines to run in a different >thread because that would require extensive rewriting. > >Thanks > > ---------------------------------------------------------------------- End of Info-LabVIEW Digest
