Stagehand Mini
2
Manual
Page 27
Battery
Backup
for
Encoder
Position
Figure 26
As the machine moves, the Position Encoder sends pulses to the motion controller. The motion controller adds
or subtracts those pulses from a position counter that is kept in memory. If power is lost, the counter is cleared
from memory and when the Stagehand powers up again the position counter will be reset to 0. With a little
imagination you can envision the trouble this can cause onstage if a Stagehand power cord is kicked out of the
wall between cues, or fuse blows, or a brown‐out occurs. Motors that are sitting out in the middle of the stage
will look to Spikemark like their position is off in the wings. If the next cue is run without noticing the issue the
motor will try to run either way too far, or not far enough and possibly cause a collision.
To prevent mishaps on stage during the show, the Stagehand has two slots on the face for a pair of 9V batteries.
The batteries will power the motion controller if main power is temporarily lost. This battery backup will keep
the position counter from resetting and thus eliminate problems associated with power outages.
The batteries only provide about an hour of power, so they shouldn’t be relied upon for long power outages. In
cases where power will be lost for an hour or more, record the position of the Stagehand and then power it
down by removing the batteries. When power is restored, use the Reset Position feature in Spikemark to reset
the Stagehand counter to the position you recorded during the power outage.
