¿Como CONECTAR un SENSOR de 3 hilos a un PLC?
How to Connect 3-Wire Sensors to a PLC S7-300
Introduction to 3-Wire Sensor Connections
- The video discusses the process of connecting 3-wire sensors to a PLC S7-300, emphasizing its importance in industrial applications.
- Common errors in this connection process are highlighted, particularly regarding the power supply for input modules and sensor connections.
Hardware Components Overview
- Key hardware components include:
- A power supply providing 24 volts DC.
- A CPU that processes inputs based on programming and generates outputs.
- Input and output modules that receive signals from sensors and send out signals accordingly.
Understanding Sensor Signals
- The video explains that 3-wire sensors can be capacitive, inductive, or photoelectric, delivering digital signals represented as binary (1s and 0s).
- For inductive sensors detecting metallic objects:
- No detection yields a signal of zero (0 volts DC).
- Detection results in a signal of one (24 volts DC).
Types of Input Modules
- Two types of input modules are discussed: those for alternating current (AC) outputs and direct current (DC) outputs.
- Focus is placed on PNP-type DC output sensors as they are most commonly used in industry. The SM321 module allows for connecting up to 16 inputs at 24 volts.
Connecting the Sensors
- Connection specifics for the three wires:
- Brown wire connects to positive (+).
- Blue wire connects to negative (-).
- Black wire serves as the output signal connected directly to the PLC's input.
Ensuring Correct Signal Reading
- It’s crucial that the negative terminal of the power source matches with the negative terminal of the input module for proper function with PNP sensors.
Identifying Terminal Connections
- Identification of terminals is essential; terminals #1 and #20 provide power supply connections—#1 being positive and #20 being negative.
Internal Connections within Modules
- The SM321 module has internal connections ensuring correct power distribution across terminals, allowing it to detect incoming digital signals effectively.
Finalizing Sensor Connections
- After identifying connections, actual wiring begins with connecting an inductive sensor:
- Brown wire goes to positive,
- Blue wire goes to negative,
- Black wire connects to PLC input.
Example Setup with Multiple Sensors
- An example illustrates how two inductive sensors can be wired using common terminal points for efficiency:
- Positive wires from both sensors connect through bridging,
Understanding Sensor Integration with PLCs
Connecting Multiple Sensors to a PLC
- The first sensor can detect metallic objects, sending an input signal to the PLC through terminal 0.5 when activated.
- A photoelectric sensor is introduced as the next type, which also sends an input signal to the PLC via terminal 1.3 upon detecting an object.
- It is recommended to use terminals and internal interconnection bridges for simplifying wiring, preventing clutter that could lead to circuit failures over time.
- Proper organization of cables (e.g., separating brown and blue wires) enhances both functionality and aesthetics in automation installations.