Casio LK-40 User Guide - Page 41

I LOCAL CONTROL (Default: on) /GM mapping (Default: off) This setting determines whether or not the keyboard and sound source of this keyboard are connected internally. When recording to a computer or other external device connected to this keyboard's MIDI IN/OUT terminal, it helps if you turn LOCAL CONTROL off. on: Anything played on the keyboard is sounded by the internal sound source and simultaneously output as a MIDI message from the MIDI OUT terminal. oFF: Anything played on the keyboard is output as a MIDI message from the MIDI OUT terminal, without being sounded by the internal sound source. Turn LOCAL CONTROL off whenever you are using the MIDI THRU function of a computer or other external device. Also note that no sound is produced by the keyboard if LOCAL CONTROL is turned off and no external device is connected. MIDI THRU MIDI IN Sound Source MIDI OUT MIDI OUT MIDI IN Sound Source MIDI OUT LOCAL CONTROL On Notes played on the keyboard are sounded by the internal sound source and output as MIDI messages from the MIDI OUT terminal. LOCAL CONTROL Off Notes played on the keyboard are output as MIDI messages from the MIDI OUT terminal, but not sounded directly by the internal sound source. The MIDI THRU terminal of the connected device can be used to return the MIDI message and sound it on this keyboard's sound source. 478B-E-041A E-39