SPLatco Knowledge Base

MS120: External inputs and outputs

The MS120 contains 4 dedicated digital inputs and 8 points which can be used as inputs or outputs. We call the latter “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.

The input-only points have the additional feature that they can be used for NPN or PNP style sensors.