Must a limiting resistor be connected to the LED of the lighting part?
The following models are not provided with a limiting resistor and so it is necessary to connect an external resistor.
Pushbutton Switches "A3D", "M2D", "A3A"
The following models provided with a limiting resistor do not require an external resistor.
Pushbutton Switches "A16" (M16), "A22" (M22), "A3P" (M2P), "A3K" (M2K), "A3S" (M2S)