Hello jambulat,
It is certainly possible to generate a square wave on the digital lines of your PCI-6534. To do this, you would use the DAQmx sample clock function or VI to specify the rate at which to output. There are certainly some examples of how to do this depending on what language you are using. In LabVIEW, go to the Example Finder (Help >> Find Examples) and browse to Hardware Input and Output >> DAQmx >> Digital Generation >> Write Dig Chan-Int Clk-Dig Start. You can delete the trigger VI if you do not need to have the output start on a trigger. Alternatively, you could use the example Write Dig Chan - Ext Clk and make it use the internal sample clock by deleting the source control on the DAQmx Timing VI. If you need it to be continuous, you can do that as well with a few modifications.
If you are using a text-based language, find the examples for your language that installed with the NI-DAQmx driver and choose one that does digital output. There may an example of the name Write Dig Chan - Ext Clk and you could just change this to use the internal clock. I recommend looking at the NI-DAQmx C Reference Help installed at Start >> Programs >> National Instruments >> NI-DAQ in order to make the modifications that you need.
If you would like additional information about this, please let us know what language you are programming in and what progress you have made.
Thanks!
Laura
