With a software-timed generation, software controls the rate at which data is generated. Software sends a separate command to the hardware to initiate each DAC conversion. In NI-DAQmx, software-timed generations are referred to as on-demand timing. Software-timed generations are also referred to as immediate or static operations. They are typically used for writing out a single value, such as a constant DC voltage.
If any AO channel on a module is used in a hardware-timed (waveform) task, no channels on that module can be used in a software-timed task
You can configure software-timed generations to simultaneously update
Only one simultaneous update task can run at a time
A hardware-timed AO task and a simultaneous update AO task cannot run at the same time