measure voltage with pci-mio-16e-1 car using single trigger

[detech]

 I am a beginner with PCI-MIO-16E-1 DAQ card. It was bought 5 years ago by someone else. Now I need to make it work to measure DC voltage,  a squarwave. The reasean is it has 12 bits.  I just ordered the BNC-2100 since I need BNC inputs. I am trying to figure out to get one DC square wave from the BNC cable, through the BNC-2100, to the DAQ board, then to LabVIEW. I see the discussion that I need MAX to start. 

The difficult thing is How do I trigger the card. I need trigger at rise edge and just single trigger to capture one squarewave. Any advice how to do it? If you have any VI exsample for me to start, it will be a great help. Thanks in advice

Liming 

[Hani R]

Hi Liming,

Before installing the hardware in the PCI slot, you want to make sure you have LabVIEW and the DAQmx driver (which will include MAX) installed.   After you install the software, shutdown your computer and place the PCI-MIO-16E-1 DAQ card in the PCI slot.  When you restart and open up MAX, your device should show up under Devices and Interfaces » NI-DAQmx Devices.  You will notice that your card will have a “Dev #” associated with it. 

Make sure your input voltage range is within the limits of your hardware.  You can connect your square wave to ACH0 and to PFI0/TRIG1 on your BNC terminal block.  If the square wave signal is coming from a floating source (not connected to the building ground) set the switch on ACH0 to FS.  Otherwise set it to GS. 

Open up the Example Finder in LabVIEW and select Hardware Input and Output » DAQmx » Analog Measurements » Voltage » Acq&Graph Voltage-Int Clk-HW Trig Restarts.vi.  Right click the While Loop and select Remove While Loop (since you only want to acquire one square wave).   You can delete the Stop Boolean, the Unbundle By Name (Status), and the OR from the block diagram.     

Configure the Physical Channel on the Front Panel to match your “Dev#/ai0” and the Sample Rate that you require.  The program should run at this point but you will still need to adjust the number of samples per channel to match the width of the square wave you are trying to acquire and the Level of the rising edge trigger (on the front panel).  If you would like to acquire a few samples before the first rising edge, then you would need to change the polymorphic (drop down selector) value of the DAQmx Start Trigger.vi to be Reference » Analog Edge.  You will then have to wire in a value to Pretrigger Samples per Channel.

There are some great resources such as Getting Started with DAQmx to get you started on your application.

I hope this helps.

[detech]

Thanks. Your reply is extreamly helpful. I already did what you suggested.

With scope, I can select DC, or AC coupling. With this card, how do I do it?

Also it there choices for input impedence, like 50 hom, 1 Mohm, or ground?

Please help

Liming

[Hani R]

Hi Liming,

Since the PCI-MIO-16E-1 does not support AC coupling, you would have to use external circuitry to get rid of the DC component of the input signal.  Also, the input impedance is not configurable on the PCI-MIO-16E-1.  The features you are describing are available on some of our digitizers such as the PCI-5112 .  Let me know if you have any more questions. 

[detech]

Hi, Hani,

Thank you very much for help.

For AC coupling I connect a 1uF capacitor in coxial cable. It works.

I made modification to acq&graph voltage -int clk-HW Trig Restarts.vi according to your suggestions.

I check the PCI-MIO-16E-1 card with measurement & automation Explorer, test panel. It works ok at sample rate (Hz) 1500000, sample to read : 500.

However, I set the same parameter to vi program, it shows error:

Error_200284 occurred at DAQmx read (analog wfm 1chan 1 samp).vi

Possible reason (s):

Some of all of the samples requested have not yet been acquired.

To wait for the samples to become available use a longer read timeout or read later in your program.

Please check me what could be wrong.

Thanks

[detech]

I read some info, and change timeout for DAQmx to -1, which makes ifinit waiting time. And then I set samples per chanell to 500, and sampling rate to be 1000000. Those parameters works good from test panel of Measurement and automation explorer.

Now I run it. I can see when block digram runs to DQAmx read.vi, it stops there (program is still runing), it looks it is going to run for ever.

I need to take 200,000 samples/second for a square wave for my tests. If DQAmx read.vi runs this slow, it will be a big problem for me. I used digital scope to test, it is very fast. But scope is 8 bit, I need reduce error. So I try to use this 12 bit card.

Please advice is it really so slow?

Liming

[detech]

But I am wondering Test Panel works good for this card. Only thing is i can not save data from test panel. I need a vi to do what Test panel does. I used your suggested example vi, but it took for ever at DQAmx read.vi

Please advice, I need to do scheduled test very soon.

Liming

[detech]

Urgent help needed to my questions above, please. I have scheduled test soon

Liming

[Hani R]

Hi Liming,

Make sure the trigger is connected to PFI0/TRIG1 on the BNC connector block.  I believe the DAQmx Read VI is waiting for the trigger signal.  That is most likely why you get the timeout error.  Did you configure the level of your trigger signal on the front panel of the VI?  The default trigger settings in the VI are a rising slope and a voltage level of 0.5V.  You may need to adjust the level to work for your particular signal. 

[detech]

Do you mean I need an external trigger signal to connect to PFI0/TRIG1 on the BNC connector block. On BNC connector block, I see PF10/AI start, I do not see PF10/TRIG1. Please can tell me more detail about this. My BNC connector is BNC-2110, just bought from NI.com.

Thanks

Liming