Knowledge Base

CC18: External inputs and outputs

The CC18 contains 16 I/O points which can each be used as inputs or outputs. We call these “bidirectional”. In effect they consist of an input and an output brought out to a single pin. If the output is OFF, an externally connected device (say an NPN sensor or a contact) can control the on/off state of the pin. If the output is turned on, it connects the I/O pin to 0V via a transistor switch.