ComputerVoltageSources

Regardless of the accuracy of the timing source or the AtomPro (and
its scientific accuracy), it is essential that an external sync
reference can be used to enable the PSIM to reliably playback at the
same exact tempo.  This could be something as simple as an audio tone.
 (I would generate a tone from a pluging in my DAW, making it
repeatable and reliable).  The issue is the frequency of the pilot
tone, whether it be something mundane and standard like a 24 ppn midi
click that tempo changes with frequency, or a higher resolution
constant clock that allows for different tempos to be subdivided from it.

A MIDI timecode-locked device is running off of its internal clock,
but is periodically checking its timecode position to the timecode
coming it is being fed from the master.  If the device is reasonably
accurate (within a milliscond or two in a minute), this method can be
employed.  A routine of error compensation is employed to keep the
slave close to the master.  Most computer based sequencing apps run in
this mode.

A MIDI click-locked device takes the 24 pulse per note midi clock
pulse stream and references all timing information to that.

gary