NI-DAQ Select_Signal() arguments

[dxh123]

iStatus = Select_Signal(iDevice, ulGpctrOutput, ulGpctrOutput,ND_LOW_TO_HIGH);

The above code appears in NI's example program "TIOgenSquareWave.c". I can find nothing in the documentation that refers to this arrangement of parameters. What's going on here? Is this documented somewhere?

Thanks
Doug Hanna

[Filipe A.]

Doug;

That line is usually used when the counter output is programmed to toggle/pulse when its Terminal Counter is reached.
The will force the output of the counter to perform the specified action and actually output a signal.
Hope this helps.
Filipe