Continuos read ( buffer) using USB port

[leonardovieira]

Hello guys, first off all i' dont know if this forum it's the right place to solve my problem if it's not i'm sorry.

A DSP ( microprocessor) it's sending signals serially to a MAX3420E ( converts serial-usb) which converts it's to a signal tranmitted via USB port. I want LABVIEW to read the signals in te USB port and plot the signals (wave) in a chart.
But the data come to fast, so I want so make a buffer to put a part of the wave in the chart every seconds, if I don't to this she signal is 60 hz so would be impossible to distinguish the wave.
How will I be able to do this?

I read somewhere a example of this using the VI's Analog Input, AI Config, AI Start, AI Read e AI Clear but I think this VI's are only valid using the NI hardware, but i don't have any of them..

What can I do to solve my problems?


TY.

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[leonardovieira]

Cross posted here

http://lavag.org/topic/12783-a-hand-in-circular-buffer/page__p__76439__hl__device__fromsearch__1#ent...

[Dennis_Knutson]

What do you mean 'data come to fast'? If you truly mean a 60 Hz signal, then there should be no problem. What do you have the chart history set to? Can you post your code?

[leonardovieira]

Dennis I've attached my code .

My partner is responsable for reading the data so my part was design the circular buffer. I've simulated a waveform like a would receive from the isntrument

 60 hz 180V  sampling info 7680 #s 1000.

I said too fast for the human eye to recognized. When I run my code I can see the data in a graph but its  tooo fast.

My idea wast do a circular buffer to see some periods of the wave for example; I would create a buffer so when  the incoming   data outcomes the buffer size  it automatics come back to the beggining of buffer and starts replacing again. So chosing the correct read size of buffer i could see some periods of the data.

My base in this code was the circular buffer in NI site http://zone.ni.com/devzone/cda/tut/p/id/7188 so i've shaped for my desires .

My problem is : with the circular buffer the data still come too fast it's too "polluted" its dificult to distinguish,in this case my sinal is a simulated 180 V . But in fact when the "real data" ( from a enviroment , for eg a socket)  comes , i woul be able to see anything , because my voltage is variant.