RARM = 1: 0 pre-trigger samples, wait for Spear Event 1 to trigger.
RARM = 8006: pre-trigger == full buffer depth (any number > buffer
depth is clipped), wait for Spear Event 6.
RARM = -16: post-trigger 16 samples using soft-trigger.
Synchronously trigger two histories, zero pre-trigger samples:
// arm on event 2
lcaPut('116-BPM:history.RARM',2)
lcaPut('132-BPM:history.RARM',2)
// raise event
lcaPut('Spear:Event2', 1)