Canon Speedlite 600EX II-RT Manual (en)

Linked Shooting with Radio Transmission
Set the transmitters in the same way 
if any are to be used in linked 
When changing the setting from 
“slave unit” to “master unit” in step 2, 
other Speedlites (or transmitters) that 
were set as “master unit” until then 
automatically switch to “slave unit”.
Set up the slave camera units.
Set up all the slave camera units 
within approx. 30 m/98.4 ft. of the 
master camera unit.
Check that the <D> lamps of the 
slave units are lit in green.
Take the picture.
Check that the <D> lamp of the 
master unit is lit in green and take the 
The slave camera units are released 
with the release of the master camera 
After shooting with linked shooting, 
the <D> lamps of the slave units 
are briefly lit in orange.
When you want to clear linked shooting, operate the Speedlites one by 
one to change the setting to <P> in step 1.
You can use this function as a remote control for linked shooting without 
attaching a Speedlite to a camera. When function button 1 <L> on 
the master flash is pressed, all the slave camera units will be released.
During linked shooting, the time until auto power off takes effect is 
approx. 5 min. for both the master and the slave units. When the interval 
of linked shooting is 5 min. or longer, set the “Auto power off” to “OFF” on 
both the master and the slave units (C.Fn-01-1, p.113).
When C.Fn-20-1 is set (p.116), the beep will sound on each fully charged 
flash unit (master/slave).