Testing [AI SENSE] &[RESERVED] lines

[the_intern]

TO WHOM IT MAY BE CONCERN:

What signals should I connect to AI SENSE and AI SENSE2 of the NI PCI 6289 in order to test them externaly? What sort of signals can I connect to these 2 lines?

Also, the same question is for the 3 RESERVED lines from the NI PCI 6541? What sort of signals can I connect to these 3 lines? Static DIO... ?

I know I can test them by using self-test panel and such, but I want to design a circuit that will be testing those 5 lines, separately?

Any recomendations?

[Brooks_C]

Hello the_intern,

The AI SENSE and AI SENSE2 channels on the NI PCI-6289 card are the card’s references for the analog input channels.  AI SENSE covers AI channels <1…15> and AI SENSE2 covers channels <16…63> and <64…79> as described on page 3-2 of the M Series User Manual.  There are a number of sensors that you can use to test the AI SENSE and AI SENSE2 pins on your card and it depends on which sensor you have as to how you wire the sensor.  See page 4-14 of the M Series User Manual for a summary of the different connection types (in the pages following this table it describes in more detail how to choose which one to use).  If you have a floating signal sensor then you can test the AI SENSE pins by using either a non-referenced single ended (NRSE) or referenced single ended (RSE) connection to test the channel.  If your sensor is grounded then you should only use NRSE since using RSE with a grounded sensor may cause a ground loop and damage either the card or the sensor.

The reserved lines of the NI PCI-6541 are “reserved for future use, do connect to these pins” as per page 17 of the NI Digital Waveform Generator/Analyzer Getting Started Guide which covers your card.  This means that they should not be tested.

I hope this helps!

[the_intern]

Thanks Brooks_C,

But then what are AI GND for ?

My NI PCI 6289 has 32 AI [AI 0 through AI 31]. Where do you see all the way up to 79?

If I connect AO 0 (i.e 6.5V) to all 32 AI lines, does it mean that AI SENSE and AI SENSE should be conected to the same ground [GND] / referrence as the AO 0 ground is ?

I definitely want to use Analog Output voltage for all 32 AI lines...

[Neal M]

Hello the_intern,

I think there is some confusion with what you are trying to accomplish and what the AI SENSE and AI GROUND pins are used for. What do you mean by testing these pins externally?  Do you mean that you are trying to use your analog inputs to read a voltage signal (6.5V)? Or are you actually trying to see what the pins do using another measurement setup?

If you are trying to do the former, how you connect your signal depends on how you want to take the measurement.  There are three options: Differential, Referenced Single Ended (RSE), and Nonreferenced Signal Ended (NRSE).  Differential signals use 2 AI inputs so that you can measure the difference between 2 voltages (without a ground).  RSE uses the card ground (AI GND) to provide a reference to which the AI voltage is measured. NRSE uses the source ground (AI SENSE) to provide the reference to measure from.  It is all explained very well in our Field Wiring and Noise Considerations for Analog Signals Developer Zone article.  Table 1 in this article (about a third of the way down) gives a good summary and shows how to connect your signals.

The benefit of RSE and NRSE is that you have access to all your channels (in your case 31).  The only catch is that you must use the same ground for all your signals.  Your card provides a little more functionality  with NRSE in that you can use 2 grounds, AI SENSE for AI <0...15> and AI SENSE2 for AI <15+>.

So, in so many words, the answer to your question (assuming you are using NRSE) you are correct in that you must connect both AI SENSE pins to your signals ground, and then the + terminal to all of the AI inputs.

[the_intern]

Thanks Neil,

This is my plan for the Analog Input lines. I am going to connect AO 0 of lets say 6V to all 32 AI lines having resistor in between each as a voltage drop, so that each AI lines read slight lower voltage than 6V. In this case, I would leave SENSE and SENSE 2 connect to the AO GND that AO 0 is using or to the AI GND, or the the main power GND?

How about testing the PFI lines (16 of them). As I understand, only tow of those lines are actually counters, whereas other 14 are just additional features for the CTR, therefore can be tested as static DIO. Connect one to another and test their connectivity by W/R high/low... Any thought on testing these 16 PFI lines ?

Thanks

[the_intern]

Can I connect PFI 14 (frequency out) to PFI 12 (CTR 0) and to PFI 13 (CTR1) and test those two counters in that way ?

What frequency can I generate from PFI 14 ?

[Neal M]

Hello again the_intern,

The method to test your analong inputs sounds valid, but you may want to consider hooking the AO directly to the AI lines.  This way they would all be recieving the same voltage and you could see if the inputs differ in any way (they shouldn't since there is only one Analog to Digital Converter on your card).  The grounds for the two are internally connected, so you do not need to wire these at all (as long as you use RSE analog input, see the link in my previous post).

The PFI lines are basically customizable pins.  You can route signals out of them (for example a sample clock) or input signals as well (for example an external clock).  It appears from the pinout of your device that all of your PFI lines double as DIO lines as well.   So to test these, you could configure 3 ports to be output, and 3 to be input (total 6 ports) and then wire the out to the in.  Testing the counters is more complicated.  They use the same pins (PFI lines), but they can be used for many applications.  Our counters can be used to output (for example a pulse train) or input (for example edge counting).

We also allow for internal routing of signals so you do not need external wiring.  For example, you can specify the input physical channel in your program as "Dev1/_ao0_vs_aognd" and it will read your AO 0 referenced to AO GND without any wiring.  You can see these internal channels (in LabVIEW) by right clicking on your Physical Channel indicator or constant and selecting I/O Name Filtering...:



You then select Internal Channels:



You might also want to take a look at our Diagnostic Utility.  The readme explains in more detail, but it esentially tests (almost) all the hardware on the card.  This might make your job easier.

Message Edited by Neal M on 12-07-2007 12:54 PM