oscarc

Hi, I have a program which is supposed to measure with a daq during 20 seconds every 30 seconds, and then perform an ftt, and then save the data. The problem is, I get performance leaks, and this app. is supposed to run for a couple of days. The number of cycles it manages to measure decays almost exponentially. I first tried a version with queues, where after each 20 seconds, data was stored in the queue, and then obtained for further analysis. And, I did release the queue every cycle, thought that might be good just in case. But, now I tried using global variables instead, and that also gets clogged down; I guess there must be something else slowing down my VI, but I can't figure it out. I have a couple of shift registers, perhaps that is what is causing the bad performance? I will attach som pictures of the VI: Regards Oscar

Hi, I have a project where I am using a daq to measure acceleration. I want to measure high frequencies ~30kHz, and I use a producer/consumer loop to do the measuring in the producer loop, and the fft:s and saving part in the consumer loop. I will let my system run continously, but I want to save averaged data at specific times (with a timestamp on), for certain periods: saving saving saving etc. _________-------_________-------_________-------____ t1 t2 --->t Currently I was thinking of using t1 = 20s and t2 = 10s, but I will want to control them later. I was wondering about what method to use, so that the consumer loop will still be processing the averaging and saving part. I guess I can use two time elapsed vi:s which control a case structure in which I place the saving part, but it would be messy. I was wondering if the timed loop is good for controlling this, but it seems not.. Many thanks for your help! Oscar

QUOTE (Y-P @ May 9 2009, 09:05 AM) Hi, oh, I am sorry that I forgot to mention that the computer will stand in a factory (protected), where only highly resilent equipment will work; much water, and much sols in the physical measurement environment. I will us a switch which will be durable enough, with tape-sealed cable endings. I was recomended using the usb-vi:s from data translation, which I can place in a loop, and when triggered, will start my intended measurement setup when buton is pressed. Anyone familiar with those VI:s? Regards Oscar

Hi everyone, my first post. I need to have an external physical start button that will trigger an event in my code. I was thinking of either using the USB or COM-port to do this. But before cuting wires, I wanted to ask if anyone has done this? I was thinking of using Visa to send a voltage through a COM-port channel, and detect if I receive a signal in another channel from the button being pressed, thus starting the rest of my code. But is it a good solution to continiously suppla a voltage in one channel? I am not so familiar with the VISA .VIs, so any help is appreciated! Regards Oscar