Analog Triggering of a Digital Signal

[Edoardo]

Hi everyone,

that's my problem: I want to trigger a digital output with an analog trigger (input).

I'll explain better. I want that when my analog signal reaches a fixed threshold the Labview program generates a short digital step (010).

I'm Using a PXI 1042Q with a PXI 6733 board with SCB 68 on it and a TB 2709 board.

Can someone help me with this?

I have written this program that I attach but it continues to give err -200452, Specified property is not supported by the device or not applicable in the task.

the error occur when it reach the trigger.

Thank you,

Edo 

[Timmar]

I may have missed something but the card you have specified is an analogue output with some high speed digital I/O.

You have no analogue input hardware to allow a trigger to be generated.

Is your signal deterministic? - Can you calculate when the trigger is to occur?

If so, your best bet is to compose the analogue waveform(s) and calculate a digital waveform of the same length containing the trigger or triggers.

Then you clock the signals out together (This is an effort in itself, look at the sychronising examples in ni help) Hint: they will need to share a clock or trigger a counter in some way. Hey presto, Job done.

If they are not deterministic eg you are using an .mp3, you will have to do some dsp style processing and look look at some way of sending waveform chunks to your digital output channel. 

I would love that job!  Assuming your card is capable, I fear that it would take a significant ammount of time to develop a working solution.

[Edoardo]

Hi, 

the TB-2709 has 8 analog input lines.

My signal is not deterministic, so I cannot predict when I will need to generate the signal.

It's a conceptually easy problem, I want to generate a signal triggered with an analog input. So when the input cross a specified edge with a specified slope, Labview generates the signal. This signal will be used as an external trigger for other instrumets.

I'm sure that Labview can do it! The question is... How?

Edo

[F._Schubert]

The TB-2709 is just a terminal block. You need the approiate PXI DAQ card connected to it to aquire an input voltage. This card needs to support analog triggering for your concept.

Felix

[Edoardo]

Ok I'm sure I can acquire an analog trigger.

I also manage to do an analog trigger reading, so I can acquire an Analog Signal triggering it with an analog trigger.

What I can't do is write a signal with an Analog Trigger... 

Edo

[Timmar]

I don't know how to do it on your hardware,

There are 2 standard paths:

1. If Your hardware has Analogue inputs and digital outputs on the same device. The triggers can be accessed from other subsystems.

2. if you are using 2 seperate devices, you will need to route the triggers onto the RTSI Bus in the back of the PXI Chassis.

eg. Generate trigger from AI on Dev1 PFI 15,  Set output based on Dev2 PFI15