Casio CTK-691 - Manual (Page 20)

Connections
E-18
J Soft Pedal
Depressing the pedal softens the sound of the notes being
played.
J Rhythm Start/Stop Pedal
In this case, the pedal performs the same functions as the
START/STOP button.
Use only the accessories and options specified for this
keyboard. Use of non-authorized items creates the danger of
fire, electrical shock, and personal injury.
Accessories and Options
705A-E-020A