Canon 540EZ - Manual (Page 12)

4. Setting the Main Switch
The main switch as three setting positions, as described below.
0
0 : Turns the power off.
1 : Turns the power on. The power is
always on when the switch is set
to this position
SE : Turns the power on and activates
the SE (Save Energy) function.
The SE function automatically
turns off the power after 90 sec­
onds of non-operation to prevent
unnecessary battery consump­
tion. The LCD panel display also
goes off when the SE function
activates. The power comes back
on when the camera’s shutter
button is pressed halfway or the
test firing button is pressed.
If the main switch is set to the SE oosition when using the Command Back Et's
interval timer function, power to the flash is automatically turned on one minute
before the picture is taken.
Mode Memory Function
When the power is turned off, the 540EZ's mode memory function automatically
memorizes all of the flash unit's settings including the flash mode, zoom position
and flash exposure compensation level. When you turn the flash back on, all of
the settings are automatically restored to the same state you left them in.
To make sure the mode memory function holds the flash settings in memory
when you exchange batteries, first turn off the main switches on both the flash
and camera, then exchange the batteries quickly by loading the new batteries
within one minute after removing the old batteries.