high speed output of custom bits

[hubcio99]

Hi all.

I am building my own communication message protocol and I am looking for NI device or HW to output voltages of 0s (<2.5V) and 1s (>2.5V up to 5V) at speed of 1 micro-sec per bit. Lets say 1 = a transition from 0 (holding for 0.5 micro-sec long) to 1 (holding for another 0.5 micro-sec long) to make the one bit = 1 micro-sec.

I have a USB-6001 device, but if I use DIO or AO channels, I can only switch between 0s and 1s every 1 msec, which is slow. Even if I have the switching done in a for-loop using NI-DAQmx software package. I am using Visual Studio C++ for my src.

Anyone has any thoughts of what NI device i can use? or maybe I should use something different than Visual Studio?

thanks

[Kevin_Price]

1. You'd definitely need to use a different DAQ device, something capable of hardware-clocked DIO.

2. You say you want 1 microsec per bit, but you also seem to expect to spend only 0.5 microsec each in logical 0 and 1 states.  To make transitions at 0.5 microsec intervals, you'll need a clock that runs at 2 MHz.

3. I'd tend to recommend an X-series device for their versatility.  Some of them are limited to 1 MHz DIO, so you need to look over the specs carefully.

4. The limitations you're facing are a combination of:

- Device capabilities: yours doesn't support hw-clocked DIO

- Software timing: can't execute software and driver calls at >= 1 MHz .  (And USB devices are more limited than desktop PCIe boards.)

5. Visual Studio should be fine.  Most of the heavy lifting will be done by the board and driver.

6. Caveat: you can't expect to receive and *interpret* incoming messages 1 bit at a time at 1 or 2 MHz.  You would need to let the board and driver buffer up a burst of bits and then post-process the whole set.

-Kevin P