Canon SPEEDLITE EL-1 Advanced User's Manual page 120

Sender Unit(s) Flash Firing ON / OFF
You can set whether or not to fire the sender unit as a wireless flash that controls the
receiver unit. When sender flash firing is turned ON, the flash fires as firing group A.
1.
Push the joystick vertically.
2.
Select an item in (1).
Push the joystick up / down / left / right or turn <
and push the joystick vertically.
120
> to select an item,