The behavior of the function / sound buttons on a cab are not defined by the DCC system but rather the decoder in the locomotive. To find out what button does what function, or triggers a certain sound on your locomotive, read the documentation that came with the loco, consult the company's website or contact them by phone.
The Bell and F1 Buttons can perform the same functions or different functions depending on how the decoder in the loco is programmed or if you have remapped the bell button to perform a different function.
The Bell button the factory default is a toggle for F1 / function 1. The default is on / off with each button press. The behavior of the Bell button can be changed using the Set Cab Params menu.
To access the Set Cab Params menu:
Press the Program / Escape key (PROG/ESC) 6 times until you see Set Cab Params Press enter 6 times until you see Assign Bell to Function.
Enter the function number that you want to be activated when the Bell button is pressed. We recommend using 1, however any function can be assigned to this button.
FYI- Older Soundtraxx Steam decoders use Function #3 for the Bell. The steam decoders can have the bell “re-mapped” to Function #1 (Diesel decoders can not re-map the bell to Function #3).
For NCE mobile decoders only, the corresponding CV information translates into:
CV35 F1 default value is 4 output 3 / green / pin 3
CV122 EFX for F1 output 3 / green / pin 3 default value is 0 - standard on / off