Problems with the SCXI-1126 Frequency Module

[Stagnok]

I am finding that, at least my modules, are not responding according to the specifications. I on all channels have not been able to get full range that I set at 0-8kz 1hz filter with a 100mv pp ac signal coming in. The spec shows a 50mv signal for all ranges down to 15hz. Alot of channels have been losing signal at > 200hz sometimes as high as 1khz.
I have tried 3 different modules and 3 difference sxci-1000 chasis on two different daq cards. All channels where configured for 0 to 8kz at 1hz filter. I am using a calibrated HP 33120A Function generator to test the channels. I am running out of things to try to get them to work properly.

[markwysong]

This sounds like a filter problem.

How are you setting the filter? Through NI-DAQ software? Do you select "all channels" when setting the filter?

Mark

[Stagnok]

I set the filter using Measurment and Automation explorer, going to Devices and Interfaces, SCXI-1000, SXCI-1126 and then properties. I did check all channels. Right now I have all channels tied together and am running in 8khz 100mpp ac signal and two channels are out of spec at 8khz. But I keep on smiling 🙂 FYI I am using a PCI-MIO16E-4 Daq card with current Nidaq drivers.

[markwysong]

Just a few questions. 🙂

1) How are you taking these measurements--with labview, using what VI, AI Single point?

2) Have you set your range to 0-8Khz and have an 8 KHz signal going in?

Mark

[Stagnok]

I am taking these measurments using the measurment and automation explorer test function. I set my range on all channels to 0-8khz and Have been inputing no more than 8khz. What leads me to believe I have a software or config problem is that I sent in a module to NI for repair and this is the brand new one they sent me back. While testing this module, I also have a 1102 module and 1124 module on the scxi-1000 chasis and both of those are working as specified. I also moved the 1126 module to slot 1 and ran it that way as well when I replaced the chasis.

[markwysong]

What DAQ card are you using to control the SCXI chassis? Do you know what the settings are? At a set frequency, what are the channels reading?

I don't mean to belittle your knowledge of the cards; I'm just trying to understand exactly what you're seeing, because I use the 1126 cards myself.

The 1126's output a maximum of 5 volts, so I usually set my DAQ range so that I get the maximum resolution out of it.

Mark

[Stagnok]

I am using a PIC-MIO16E-4 Daq card. It is set up for +/- 10vdc input I believe due to the fact that I am running a 1102 module with +/- 10v input as well. I also have a 1124 module with +/- 10v outputs on it.

[Stagnok]

I ran a test inputing 8khz and the channels where +/- apporimatly 4 hz. Stable signal, the type where you know you have a solid signal with no bounce. 2 channels were already off by 26hz at 8khz. I would drop the frequency by half and re-test and each time more channels would go out, eventually when I inputed 250hz there was only 1 channel that still had a solid non-jumpy reading within 4hz of 250. The rest were grosely out ot specs.

[Stagnok]

I am finding that using the 1126 with a sine wave and not a square wave at 50mvpp I had to set the hysteresis to .025 on all channels. With this setting I was able to get the proper readings. I do not know why this fixed the problem but it did. Also it seemed as well that movement of my machine had caused the back adapter that connects the cable to the scxi to come a tad loose.