How do i disable a polling daq process when a continuous one is running ?

[French LVer]

Greetings from France,

I'm almost new on LAVA forum and i already need your help

I'm currently on a software specification (coded in Labview) using data acquisition.

Briefly, i have two daq processes running in same time on same channels :

- a polling acquisition (one sample per channel) recording 16 channels each 10 minutes,

- and a continuous acquisition (11 channels at 1kHz each) triggered by a digital input's edge front for 10 seconds (retriggerable).

My question is :

- Is there a way to disable polling acquisitions when daq card is currently working on a continuous one (by reading daq card activity for example) ? I assume NiDaq's error will occur if both actions are asked to daq card.

If it isn't possible, i will have to continuously acquire all channels at 1kHz (analog and digital) and do triggering action by software.

Without daq hardware available right now, i can't test it by myself so i ask you all for some advice :worship:

I know this is not really relative to Labview but you might have encountered it on your own applications.

[Syd Chasm]

Bonjour, mon ami!

I have had the same issue in the past where I needed some fast sampling for some channels, and slower rates for other channels. I was using 6020E series cards, which have only 1 on-board timer. In my case, I needed to sample 80 odd channels at 1Khz, and another 50 at .5 Hz continuously for test runs of 90 minutes duration. I got around it by using separate cards for the high speed and low speed acquisitions - you can alternatively use a card that has one timer per channel, that allow you to sample each channel at a different rate simultaneously, but these are expensive.

In your case, given that one of your rates is EXTREMELY slow (1/10 mins), I would be tempted to use a while loop to count the 10 minutes and execute a single multi-channel read every 10 minutes, during which time you would suspend the triggered DAQ task. I'm assuming that it doesn't matter too much if the samples are taken at 10 minutes plus or minus a few seconds? It's not very elegant to use the windows timer to control your sampling rate, but for such a slow rate you should be OK.

I hope this is clear - if you're really stuck I could put together some sample code to show you what I mean?

Au revoir et Bonne Chance,

Syd

Greetings from France,

I'm almost new on LAVA forum and i already need your help

I'm currently on a software specification (coded in Labview) using data acquisition.

Briefly, i have two daq processes running in same time on same channels :

- a polling acquisition (one sample per channel) recording 16 channels each 10 minutes,

- and a continuous acquisition (11 channels at 1kHz each) triggered by a digital input's edge front for 10 seconds (retriggerable).

My question is :

- Is there a way to disable polling acquisitions when daq card is currently working on a continuous one (by reading daq card activity for example) ? I assume NiDaq's error will occur if both actions are asked to daq card.

If it isn't possible, i will have to continuously acquire all channels at 1kHz (analog and digital) and do triggering action by software.

Without daq hardware available right now, i can't test it by myself so i ask you all for some advice :worship:

I know this is not really relative to Labview but you might have encountered it on your own applications.

[French LVer]

Thank you for your quick reply Syd,

Your solution imply a second daq board in order to acquire low frequency data.

Perhaps, i could use a very slow daq system using RS232 for duplicated signals.

Your answer helped me in clearing ideas. Thanks again