07-28-2010 04:51 AM - edited 07-28-2010 04:54 AM
I'm working with a NI PXI 1010 and a signal generator board TB-2705 PXI. I'm also Programming in Matlab and using the traditional drivers. I need to generate a signal of which I can change the frequency, amplitude, harmonics, phases during the board is triggered. It's not been possible to make this. I have to always stop the signal, charge the new data in tha borard and start generating again.
I have an idea for a solution of this problem. I would like to know if it's possible to solve my problem like this. Otherwise I would like to be recomended with some other board or hardware that could achive this.
My idea is two use two parallel connected outputs at the same time. One would continue the signal from the other once the signal is to be changed. The problem is, that they wolud have to be totally synchronized and the second outputwould would have to immediately continue with the changed signal at the right tension value where the first signal stopped. I don't know if it is possible. because I don't know if it's possible to synchronize the two outputs so perfectly and to avoid some unwanted incoming signals and so on. I also don't know if the data can be charged in two different outputs at the same time.
Please help me with my project!
Thanks for your time.
07-29-2010 08:06 AM
the most important thing first: your idea of coupling two outputs directly WILL VERY LIKELY DAMAGE THE BOARD. This being said, let me reply to your original request:
Unfortunately, you named the PXI chassis and the connector block type, but not the type of the actual PXI card that you are using to output the signals. Please unscrew the TB-2705 connector to read the PXI card's four-digit type code and post it. Additionally, you should clarify which NI driver you are using in MatLab. Did you mean the Traditional NI-DAQ driver?
Generally speaking, the solution for your problem will be to create an output task that uses "streaming". This means that you will not download a complete, arbitrary waveform to the DAC card's memory which is then output in one go, but that you continuously provide the data "bits" for the next couple of milliseconds. This way, you can programmatically decide when to change the signal's amplitude, frequency, form, ... without having to stop the output itself.