Comunication problem between PCI-6225 and SCB-68

[jcatano]

I am connecting an SCB-68 to a PCI-6225, the connector 0 works fine, but the values I get in LabView are different that the values that i measured in the SCB-68 connector 1. How can I fix this problem?

Thanks!

[S_Hong]

Hi jcatano,

How are you measuring the voltages off of your SCB-68 connector? Across which pins are you measuring your voltages?

Have you tried using the Test Panels in Measurement and Automation Explorer to see if you were getting proper readings? You can access this tool by right-clicking on your device and selecting Test Panels.

Perhaps you can try running one of our DAQmx shipping examples to see if this might solve your issue. These can be found in your NI Example Finder by accessing it under Help » Find Examples. Depending on your application you can find the appropriate example you are looking for under Hardware Input and Output » DAQmx.

One other test I would suggest is to perform a loop-back test, that is, connect an analog output channel to an analog input channel on your board to see if you can measure anything. To do this, you can wire pin 16 (AO0) to pin 1 (AI0) and set a DC voltage in the Analog Output tab in Test Panels (Make sure to update the value). Once your output is set, go to your Analog Input tab and set your Input Configuration to RSE. You can then set your channel and measure the voltage. Hopefully you will be able to see something.

[S_Hong]

I apologize for the error. AO0 should be pin 22 and AI0 should be pin 68. Sorry for the confusion.

[jcatano]

Hi S_Hong,

Thanks for your help. As for the SCB-68, it is connected to "Connector 1" in the PCI-6225 card, therefore I believe the pin assigments are a little bit different that what you mentioned. I obtained the pin assigments from the following link:

 http://digital.ni.com/public.nsf/websearch/F011AD8B0F4BD35086257050006CBB70?OpenDocument

And what I am doing now is measuring the signal with a multimeter in the pins that are assigned for analog input and for analog ground in the SCB-68. Then I read the same pins in LabView or in the Measurement and Automation Explorer (in which i get exactly the same values), and I get a different reading from what I get using the multimeter. I have also checked the conection diagram in both LabView and MAX and everything seems to be ok.

Thanks again for your help.

[Wallace_F]

Hi jcatano,

Since you seem to be getting the same results in LabVIEW and Test Panels in Measurement & Automation Explorer, lets examine how you are measuring the signal using your multimeter.  Select an analog input channel to measure, and then tell me what pins you have the leads of your multimeter touching when you try to measure the signal.  Lastly,

how do the results from the multimeter differ from your results in LabVIEW and Measurement & Automation Explorer?  What are the measured values for each?

Best wishes,

Wallace F.