Launching the 6351 card configuration lines: why does it take so long?

[did.rider38]

Hello everyone,

I am working on an HMI with a 6351 card. It is a powerful and fast card. I am using digital inputs/outputs, analogue inputs, counters and, to manage all this, I am using different triggers. I have noticed that the launch lines take a long time to configure. I measured 400 ms. Do you know why it takes so long?

See the image in the ‘400 ms’ section...

The signals used are fast, with a sampling clock of 1 MHz. External source: 20 kHz

Have you an idea ?

best regards

[santo_13]

you're not clear enough on what you refer to as 400ms section in the image.

What is your expectation and your observation?

[did.rider38]

Hi santo_13,

Thank you for your response.

We would like to trigger on a gate signal as quickly as possible in order to start an acquisition immediately afterward.

In my VI, a 400 ms delay is observed before the acquisition starts. Could you help me drastically reduce this delay?

Thanks in advance for your response.

[did.rider38]

Now, I deleted a part of programme. I deleted Analog trigger, middle line. Is not important part. I won time. Now this while 60ms. But it's always too long.

Resume : trigger Analog has more long to configure that trigger digital.

But, sorry, I didn't show the whole VI. Before the analogue and digital configuration lines, there is a first step, a time trigger. See the image: blue curve  [5v;0V]

I detect the level change via an analogue input. I read the level value, and when it is below 2.2 V, the configuration line for the trigger is activated. This is the part you are already familiar with.

I would like to replace this approach with a digital trigger or an Arm trigger, but I don’t know how to do it.

I explained this in the following question: https://forums.ni.com/t5/Counter-Timer/A-trigger-from-a-trigger-PCI6351/m-p/4461077#M16118

[santo_13]

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@did.rider38 wrote:

Now, I deleted a part of programme. I deleted Analog trigger, middle line. Is not important part. I won time. Now this while 60ms. But it's always too long.

Resume : trigger Analog has more long to configure that trigger digital.

But, sorry, I didn't show the whole VI. Before the analogue and digital configuration lines, there is a first step, a time trigger. See the image: blue curve  [5v;0V]

I detect the level change via an analogue input. I read the level value, and when it is below 2.2 V, the configuration line for the trigger is activated. This is the part you are already familiar with.

I would like to replace this approach with a digital trigger or an Arm trigger, but I don’t know how to do it.

I explained this in the following question: https://forums.ni.com/t5/Counter-Timer/A-trigger-from-a-trigger-PCI6351/m-p/4461077#M16118

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Please share a detailed timing diagram of your input and output signals, this will help understand the requirement and advise on how to achieve using DAQmx.

My understanding so far is as follows,

1. External signal acts as a trigger (edge or level or how?)
2. Upon trigger, DAQ DO lines generate a predefined waveform
3. External signal may be up to 20kHz

[did.rider38]

There are two external signals: blue and red. The blue signal starts the timing, and the red signal triggers two output signals.

I would like to trigger the blue signal with a digital trigger