Canon 600EX-RT Instruction Manual page 81

If the transmission channels of the master unit and slave unit are different,
the slave unit does not fire. Set both to the same number.
Master Flash Firing ON/OFF
You can set whether or not to fire, as a wireless flash, the master unit
that controls the slave unit. When master flash firing is set to ON, the
master unit is fired as a slave unit of firing group A.
Even when master flash firing is set to OFF, the flash firing for controlling the
slave unit (optical transmission) is performed. Therefore, depending on the
shooting conditions, the flash fired for controlling the slave unit may be
captured in the picture.
2
Set a channel.
Press function button 1 <C>.
Turn <9> to select a channel from
1 to 4, and press the <8> button.
1
Set the <N> display.
Press function button 4 to display
<N>.
2
Set the master flash firing.
Press function button 1 <4> to
set the master flash firing to ON or
OFF.
g : Master flash firing ON
d : Master flash firing OFF
Wireless Settings
79