Canon Speedlite 600EX II-RT Manual (en)

[: Shooting in a Different Flash Mode for Each Group
Set each firing group.
Set the flash mode of each firing 
group by operating the master unit.
With <M> displayed, press 
function button 3 <F> (p).
Turn <9> to select the group to set 
the firing group.
Setting the flash mode
Press function button 2 <2>, 
then select the firing mode from 
<a>, <q>, or </>.
Setting the flash output and flash 
exposure compensation amount
Press function button 3 <1>.
Turn <9> to set the flash output or 
flash exposure compensation 
amount, then press <8>.
When using the <q> mode, set the 
flash output. When using the 
<a> or </> mode, set the 
flash exposure compensation amount 
as required.
Repeat step 3 to set the flash function 
of all firing groups.
If you press function button 2 
<@> when <M> is 
displayed, flash exposure 
compensation can be set for all the 
firing groups.