PLC (programmable logic controller) is a special computer programmed to control certain processes in industries, but it has no display, keyboard, printer or hard drive; it just hides in the control panel out on the factory floor. PLC is consistent of an input connected to a CPU connected to an output. First, a program is written and downloaded to CPU. Signal is sent to the input, convert to binary data and sent to CPU. The CPU processes the data received and sends the result to the output. The output turns the data to a raw electrical signal and applies that to the machine. PLC is used for better control on production process, higher pace and attention in the process and many other cases.
HMI (Human Machine Interface) is a device or an LCD monitor to connect human and machine together. We use HMI to monitor and control the process being conducted by PLC. It can also be programmed and used to change parameters and control the system. HMI is divided to two kinds of Touch HMI (also known as Touch panel) and Text Panel.
Electromotor is a device changing electrical energy to mechanical energy. They are widely used in many industrial and domestic appliances such as mixer machines, hairdryer, dishwasher, microwaves, to name a few. Electro motors have various types that are used in different industries depending on their function. We can refer to single-phased or three-phased electro motors. They are also divided to two kinds of cast iron and aluminum electro motors depending on body material and alloy used in their production.
Servo motor is a motor allowing the user to control the precise circular or linear movement. It is commonly used in closed control system. This device includes a control circuit, servo motor, shaft , amplifier and encoder or resolver. Servo motor is mechanically divided to circular and linear types. Electrically, we have AC and DC servo motor. In AC servo motor, speed is determined by the frequency of the applied voltage and the number of magnetic poles, but in DC servo motor, speed is proportional to the supply voltage with a constant load. Generally, AC servo motor is more common and precise.
Inductive sensor utilizes permanent and electric magnet produced from AC and DC. Generally, Inductive sensors function in magnetic field and their features can change according to magnetic field. These are non-contact sensors. There is no mechanical contact between moving and immovable parts in these inductive sensors. These sensors are divided to two types of AC and DC.
Limit switch is a switch that starts moving with the movement of a mechanical segment or the presence of an object. Limit switches are used for controlling the machines as a safety lock, or for counting the number of objects passing a spot. Limit switch is a electro mechanic device made of a mechanical operator connected to a bunch of contacts. When an object reaches a contact through an operator, the device causes connection or disconnection of contacts in order to connect or disconnect electricity flow.
Encoder is a device used for pulse output divided to two types of line encoder and rotary encoder. Also encoder is device to measure movement from one place to another. This kind of encoder is produced in different shapes, sizes and accuracy. Encoders’ main use is sensing position, direction, speed and counts. Some of the technologies involved in encoders are magnetic, mechanical, resistive and optical. Moreover, encoder is divided to absolute and incremental encoder based on signal output type.
Sensors are mainly utilized to sense and measure various elements such as pressure, heat and humidity. We use sensors in different measuring devices and analogue and digital controlling systems like PLC. Sensors function and their ability to be attached to different devices such as PLC have changed them to an inseparable part of automatic controlling devices. Sensors, according to their types and functions programmed for them, send the data to controlling system and system works based on the designed program.
Pressure Sensor: It is a device measuring pressure that changes pressure mechanical parameter to electrical output signal.
Temperature/Heat Sensor: It is a type of sensor that measure heat or temperature. These sensor exist in different types, from simple on/off thermostat in a house heater to very sensitive semiconductors controlling the processes in a factory kilns.
Humidity Sensor: This type of sensor measures and reports the approximate humidity level in the air. It is commonly used in houses, workshops, vehicles, industrial air conditioners, weather forecast stations and working places in which humidity have a negative impact.
Load Cell/Weight Sensor: It is a type of electrical sensor used for measuring weight and force and is produced in different kinds of tensile, bending, compressive and torsional. This sensor is utilized in factories to measure the tension of cables, tension of thread in textile factories and in other types of industries.
Safety Light Curtain Sensor: It is used to protect valuable items and avoid hazardous areas in factories. Safety light curtains consist of sensors that work differently based on their function. The number of beams, the distance between beams and generally the height of light beams are the different parameters of these sensors.
Photoelectric Sensor: This is a kind of positioning sensor. The sensor uses a beam of light in doing this process. This beam of light is either reflected or cut off by the target object. These sensors have a light emitting source, a receiver for transmitting light, and electronic circuits to amplify the received signal and transmit it to control circuits. Application of these sensors include product counts, fault detection in appearance, entry and exit, detection of metal canned compounds, and some other applications.
Power supply is an electronic device providing electric energy. This device is divided to different types:
Power Supply DC: This changes AC (alternating current) to DC (direct current).
Switching Power Supply: It reduces AC voltage in order to reach to proper domain AC signal.
UPS: This is a device which provides electrical energy in power cut.
High Voltage Power Supply: It provides high voltage like 1KV.
One of the most important equipment used in most of the projects is temperature controller and displayer. As clear from its name, this device is responsible for controlling different parameters. This device is utilized for establishing the proper temperature condition. Temperature controllers, depending on the type of input they receive and the type of process they go through, are divided to different models.