PCI 6243 and PCI 6289 cards does not work properly

[eesen]

Hello,

 I have two card  ;PCI 6143 and PCI 6289. I install them to my RT target. When ı give no signal to PCI 6289 card's anolog input channel A0 and trie to read it, ı read 10 volt DC voltage. I shoul read only noise , where 10 volts DC comes from.

Another problem is that ı give square wave to my cards (PCI 6143 and PCI 6289) but in test panel (in MAX) i read a wave like sinusoid.

 For PCI 6243 ı give 3 volt peak to peak but ı read 6 volt peak to peak. What happenings?

[Neil_S.]

eesen,

Thank you for contacting National Instruments.  When you do not drive an analog input channel to a specific voltage you have no idea what voltage that channel is at.  Voltage is a relative measurement.  You can only measure voltage between two different locations.  With nothing connected to a channel the channel is floating and has no reference.  Usually it will rail to either the maximum or minimum range of the channel depending on the input circuitry.  You are only sure to see 0V on the channel if you drive the channel to 0V.  If you are using differential configuration you can connect the two input channels together.  If you are using NRSE or RSE you can connect the channel to AIGND to get a 0V reading.

The test panel reads on demand by default.  Reading the analog channel on-demand is essentially like sampling at a very slow rate.  As a result a faster square wave will likely not even be detected.  Configure the test panel as in the picture below:

Even when reading in continuous mode you will need to make sure that the square wave is slow enough that it can be read at the rate at which you are sampling.

With the 6143, confirm that you have supplied the ground reference to the card as well as the signal.  Also confirm the signal generator is setup to generate for high impedance or high Z.  At what rate are you sampling?  What type of signal are you measuring?  Is it a sine wave, a square wave, or another type of signal?

Let me know if you have any additional questions.

Regards,

Neil S.
Applications Engineer
National Instruments

Message Edited by Neil S. on 01-19-2007 05:23 PM