Hey dfwmike,
You are correct in that your 6533 board is not a counter device. It is possible to generate a pulse wave with your digital I/O device. There are example programs that ship with the driver that can be used for digital generation. If you are using LabVIEW, you can use the NI Example Finder and browse (by task) to the following: Hardware Input and Output -> DAQmx -> Digital Generation. Here you can check out all the different kinds of examples to generate digital waveforms. They all use the DAQmx Write.VI in them in one way or another. Check out the example called Cont Write Dig Chan (either Burst or Pipelined Sample Clock).VI. If you are using C, then browse to the following directory: C:\Documents and Settings\All Users\Documents\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Digital\Generate Values. Again check out those examples to give you an idea of creating a continous digital generation pattern.
For a pulse wave, you basically have to input the data into the DAQmx Write function that you want to output. You can create an array of booleans that just toggle: 0, 1, 0, 1, 0, 1, 0, 1..... or you can input a count up for U8 values, which for one channel will give you the same as toggling booleans. For different periods and frequencies, you can adjust your data accordingly even running at the same sample clock rate. For example 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1.... etc.
For a description of the Sample Clock, I again would point you to the documentation, the <a href="http://digital.ni.com/manuals.nsf/websearch/CCB88DC67022A750862573A7007ACAB7" target="_blank">NI 6533/6534 for NI-DAQmx Help</a> file. In the help file, if you search for Sample Clock, you will find all kinds of useful information. The Sample Clock is basically the internal clock, but you can also use an external clock as the Sample Clock. Here is a snippet from the Help Documentation:
"The Sample clock is the primary timebase for the DIO device. This clock controls the rate at which samples are acquired or generated. Each period of the Sample clock is capable of initiating the acquisition or generation of one sample per channel.
<img src="mk:@MSITStore:C:\Documents%20and%20Settings\rmorris\My%20Documents\6533_6534\6533_34%20Help\653x.chm::/note.gif">
Note In Traditional NI-DAQ (Legacy), the Sample clock is called the scan clock or the scan interval counter.
You also can use an external source as your Sample clock. An example of using an external Sample clock is sharing the Sample clock of an analog input device so that you can synchronize the analog and digital operations.Using NI-DAQmx, you can specify the interval (how fast the clock acquires or generates signals) by specifying the sample rate (called the scan rate or update rate in Traditional NI-DAQ (Legacy)).You can also use NI-DAQmx to export your Sample clock to other devices using the DAQmx Export Signal VI or the DAQmxExportSignal function."
I hope this helps. Please use the help documentaion and the example programs, as they will answer many of your questions. If you still have further questions, please let me know. Thanks, and have a great day.
Regards,
DJ L.