Yamaha CL1 Reference Manual page 222

3.
Press the MIDI/GPI button.
The MIDI SETUP screen will appear.
4.
Press the GPI tab.
The GPI page will appear.
3
1
2
1
GPI IN status indicator
This indicates the status of the voltage being input to the GPI IN port.
2
POLARITY MODE select button
This button selects the polarity of the GPI IN port.
............ (Low active) When operating an on/off-type parameter, it will become active
when the switch is grounded.
............ (High active) When operating an on/off-type parameter, it will become active
when the switch is opened or when a high-level voltage is input.
3
GPI IN SETUP popup button
Press this button to open the GPI IN SETUP popup window.
The button shows the name of the currently selected function or parameter.
5.
Specify the POLARITY MODE for each port.
For each port, select either low-active or high-active as appropriate for the specifications of the
external device you're using.
222
Other functions
Reference Manual