In this two-part video series, you will learn how to wire a 2-wire DC sensor, like a switch or a contact, to a PLC input card. You will also learn what a 2-Wire Discrete sensor is and recognize some of the common types of 2-Wire Discrete sensors. DC sensors can be used to indicate the state of a device or a process to the PLC program. Knowing these input states can allow the PLC program to make decisions, such as, when to start or stop a pump. Discrete DC Sensors, or discrete Direct Current sensors, operate in a circuit with a battery or other power source, commonly known as a power supply. A power supply is placed in an electrical circuit to provide power to the connected devices, like a switch, or a lamp. DC power supplies are referred to by their voltage and capacity, indicated by how many amperes they can supply. The more amperes a power supply can deliver, the larger and more expensive they generally are. In DC PLC circuits, the power supply almost always supplies 24 Volts DC to the connected devices.
