UART Communication with Microcontroller using Labview & USB 6509

[hedgy]

Hello,

 I am using Lbview NI-daq drivers to communicate with a PIC via USB-6509 and I have (at least... ) two questions:

- how do you set/turn off the input digital filter in the USB 6509?

- I have tried to understand at what speed the USB-6509 can change the state of a digital line, and to do so I used Labview to write 1-0 on a line.  I put a delay of 10ms in the Labview loop and I looked on the oscilloscope: the square wave meaured on the line the the output of USB 6509 had a timing uncertainty of about 5ms!!! That puts the communication "speed" of USB 6509 to about 200 Hz.... is this all I got for mt $400?

I am a relative novice at all this, so I will not be surprised if I am missing something large....

Thanks.

[Dennis_Knutson]

As the specs state, timing on the 6509 is software based. That means that you are subject to the type of computer, the os, how you wrote your program, etc. A jitter of 5 msec is not at all unexpected on a non-real time OS such as windows and is actually towards the low end of what you might see. While $400 may seem like quite a bit, it's considered low cost. For precise timing and higher rates, you would need to use hardware timed digital I/O. How many lines do you need and what kind of rate? You might want to talk to your local sales engineer about the different options.