slow stripchart

[Loocki]

Hello!

I am using the USB-6008 device to acquire voltage from 2 Channels and to write 5V out to 2 Digital channels in a 100Hz frequency. As I acquire the data from the 2 channels(I just use one task for that), I simultanously plot the Data to 2 stripcharts (this action is synchronized with the Digital channels. Doing this, it seems that the Diplay just changes every few seconds, for when I  change the  Voltage it takes a time to refresh while the old data remains on the screen. This is for DC voltage. When I read in a pulse sequence it is supposed to show just the top values so I get a line on the screen.It works too, but this takes about 8 or more seconds to show the wished screen....it does not matter whether I put the plotfunction into the timing functionor not..........what can I do? Or did I just come to the limits of my device?

Thanks and greets

Sebastian

[JGS]

Hello Sebastian,

I do not think that you are at the limit of the device.

The USB-6008 is a "slow" device but from its specifications still operates at over 150 Hz for analog output or 10 kHz for analog input. If you look into another thread (timing problem application using DAQmx functions, http://forums.ni.com/ni/board/message?board.id=180&message.id=31611) you see people working at a rate far over 100 Hz. My application does include adding data points to a stripchart. Note that the update is even faster than the refresh rate of the monitor.

My suggestion: try you application where you disable a few plot commands or output commands or ... ... by commenting these lines with // and find so the bottleneck for the slow (< 1 Hz) update speed.

Succes, Jos