"triggered" signal?

[redoo1997]

I'm using PCI 5112 high speed digitizer and PCI 6713 to setup a signal acquisition system. I need to turn off a switch (AO output to 6713)as soon as a signal is picked out by edge trigger (5112). The problem is, I don't see a "triggered" signal output in any NI-scope VIs. Is there anyway I can let 5112 send out a "triggered" signal to Labview so I can use software trigger to send out AO signal to 6713? This sounds like a pretty easy job but I'm kind of stuck here. Any suggestions highly welcome!

ps, I found that 5112 can output trigger to PFI line and 6713 actually accept PFI trigger. But do I need a physical connection from PFI port of
5112 to PFI connector in 6713 (SCB-68 box)? Is PFI a software line or hardware line?

Thank you very much!

Redoo

[Alan_L]

Redoo,

As you know, a hardware solution in this case will lead to a much faster response (lower latency) in turning off the switch. Is this a digital edge trigger that the 5112 is waiting for? Also, does it come from some external source? If so, you could potentially wire the same trigger to both the 5112 and 6713 and then configure the 6713 to wait for it as well. Once the trigger pulses, perform your acquisition and turn off the switch simultaneously. In any event, PFI stands for "Programmable Function Input" and is a part of the hardware. You can take a look at the pinout for your boards and will find certain lines listed as PFI. They are always digital -- and while are usually inputs to the hardware, sometimes the same pins correspond to board outputs as well (to send triggers, for example). You could also implement a solution in software, essentially by outputting your analog signal from the 6713 as soon as the Scope Read VI returns data (making sure that it hasn't timed out).

I hope that this answers your question!

Thanks,
Alan L
Applications Engineer
National Instruments

[redoo]

Thanks Alan.

I have noticed that there is a PFI port on 5112 and several PFI connector in SCB-68 box. Does it mean I need to buy a special PFI wire/cable to connect the two and let it work?

As for the software solution, I wonder if you can give me more details. I am using DC voltage edge trigger on 5112. I wish to turn off the switch as soon as the voltage is high enough. That means I can not use "acquisition status" VI cause it only tells if the acquisition is finished or not. I'd rather like a "triggered" signal from any VI. So far I can not think of a way to do it. Can you enlighten me please?

[psisterhen]

Even if the 5112 is using an Analog Edge Trigger, you can still output a "triggered" signal. In LabVIEW, you can use either niScope Export Signal.vi or niScope Configure Trigger Output.vi. If you use niScope Export Signal.vi, set the signal terminal to Reference Trigger. If you use the niScope Configure Trigger Output.vi, set the trigger event terminal to Stop Trigger. These signals are digital events that occur when the scope is triggered by the analog input signal.

These can be routed (using the same VIs) to the PFI lines or the RTSI lines. The 6713 may be configured to stop generating when it receives a digital signal on that line.

Hope that provides some more help.

Patrick

[psisterhen]

To clarify, in your application the Reference Trigger (also called the Stop Trigger) will be output when your input voltage gets high enough. This will be a digital signal you can send to the 6713 to stop the generation. You will not have to check the acquisition status in software, since these will be automatically generated hardware signals.

Patrick

[redoo1997]

I found the NiScope Configure Trigger Output.vi but not the NiScope Export Signal.vi.

anyway, in Configure Trigger Output.vi, I still don't know which trigger output source I should use. Can the trigger output signal be sent to another VI without any physical wires linked between 6713 and 5112? Where and how is this signal sent out?

Also, in configuring AO trigger, I used AO trigger and gate configure.vi, but I can not find a suitable trigger or gate source to use the signal from trigger output.vi mentioned above.

Thanks for the help!

[redoo1997]

---

@psisterhen wrote:
To clarify, in your application the Reference Trigger (also called the Stop Trigger) will be output when your input voltage gets high enough. This will be a digital signal you can send to the 6713 to stop the generation. You will not have to check the acquisition status in software, since these will be automatically generated hardware signals.

Patrick

---

By "send" do you mean send via software (i.e., links between VIs) or hardware (cables connecting 5112 with 6713)?

thank you very much!

[psisterhen]

I meant send via hardware. The PFI and RTSI lines allow you to send and receive electrical signals to and from other hardware. The RTSI bus is an 8 line parallel bus that is connected between devices inside your computer (in a PXI chassis, there is no need to connect them manually). On your 5112, there is a PFI line on the front panel of the device. It is the SMB connector (the smaller one).

You may want to review the documentation included with the drivers for diagrams of the terminal assignments for the 6713.

As Alan pointed out, the only way to catch this signal in software is to do a small read and see if it returns data (it will only return data when the trigger has been received [assuming you are not fetching from the start of the record]). However, as Alan also pointed out, this will be much slower and not deterministic. It sounds like the hardware triggering solution is right for your application.

[redoo1997]

I found a small SMA connector and connected PFI port with 6713 card interface (i.e. SCB-68) box. Also I have ordered RTSI cable from NI.

But then, when I tried to program PFI to transfer the trigger, I got error messages.

The message came from NIscope Configure Trigger Output.VI. No matter what trigger event and trigger output source I choose, it says:

Error occurred at: niScope Configure Trigger Output.vi
Driver Status: (Hex 0xBFFA0010)
Invalid value for parameter or property.

I don't even have the PFI connected. Is it possible that I need to "release the PFI line" after using it? Or somehow PFI is not supported by NI5112?

I have attached the VI below. Please give me some suggestions as the deadline is coming close.

Edit: I opened niScope Configure Trigger Output.vi and found that in "instrument handle" it only accept the following addresses:
ASRL10::INSTR
ASRL11::INSTR
ASRL1:INSTR
PXI2::0::INSTR
PXI2::2::INSTR

There is no DAQ::1 in it. maybe that's the reason it won't recognize my input?

Message Edited by redoo1997 on 04-29-2005 10:26 AM

[psisterhen]

No, your device name is fine. "DAQ::1" should work as long as your 5112 is called "Device 1" in MAX. (The names you see in that control are the VISA names of devices in your system. These are not useful when programming with NI-SCOPE.)

The problem is that the SMB on the 5112 is PFI 1, not PFI 0. Change the "trigger output source" terminal of niScope Configure Trigger Output.vi from PFI 0 to PFI 1 in your block diagram.

Be sure to review the documentation for the terminal assignments for both the 5112 and 6713. That could help avoid further confusion.

Patrick