Basics of Siemens PLCs 200
This class introduces the parts and operations of Siemens programmable logic controllers (PLCs) and describes the functions and different programming languages you will find on these PLCs.
Number of Lessons 15
- What is a PLC?
- History of PLCs
- PLC Components
- How a PLC Works
- PLC Inputs and Outputs
- Central Processing Unit (CPU)
- Input Devices
- Output Devices
- Human Machine Interface (HMI)
- Programming Device
- PLC Programming Concepts
- Contact and Coil Instructions
- Additional PLC Instructions
- Define PLCs.
- Describe the history of PLCs.
- Identify the main components of a Siemens PLC system.
- Describe how a PLC works.
- Describe how information moves through a PLC.
- Describe the role of PLC central processing units.
- Identify common input devices.
- Identify common output devices.
- Describe human machine interfaces.
- Describe how PLCs are programmed.
- Identify basic PLC logic functions.
- Describe how contact and coil instructions are used with PLCs.
- Describe additional PLC instructions.
An output device that changes the condition of a physical component of a machine or process. For example, some actuators can start and stop a motor or open and close a control valve.
An input/output device or module that uses a variable signal, as opposed to an on or off (binary) signal. Variable signals are often used to communicate conditions in a machine or process, such as temperature, pressure, and rate of flow.
analog input device
An input device that sends a PLC a variable current or voltage signal.
analog output device
An output device that receives a variable current or voltage signal from a PLC.
A Boolean logic function that requires all inputs to be binary 1’s for the output to be a binary 1.
The use of self-regulated equipment, processes, or systems that meet manufacturing requirements with limited human intervention.
A number system that has a base of 2 and uses only two characters, 1 and 0.
A binary digit. The smallest unit of information on a computer.
A type of mathematics that deals with the use of logical operators such as OR, AND, and NOT.
central processing unit
CPU. The main device that processes information and carries out instructions in a PLC. Also known as the processor or controller.
A port on a PLC that allows it to be connected to a specific type of device or computer network.
A type of instruction in a PLC program that counts items or events.
Central Processing Unit. The main device that processes information and carries out instructions in a PLC. Also known as the processor, or controller.
An input/output device or module that recognizes only binary on/off signals. A pushbutton is an example of a discrete input device, and a light is an example of a discrete output device.
discrete input device
An input device that recognizes only binary on/off signals. A pushbutton is an example of a discrete input device.
discrete output device
An output device that recognizes only binary on/off signals. A light is an example of a discrete output device.
function block diagram
FBD. A graphical PLC programming language defined in the IEC 61131 standard that uses a box format to represent instructions.
The physical equipment used in a computer system. PLC hardware includes the CPU, power supply, input/output section, and programming device.
A method of controlling machines based on the interconnection of control devices instead of through program in a PLC.
Human machine interface. A device connected to a PLC to allow operation and maintenance personnel to monitor and control a machine or process.
human machine interface
HMI. A device connected to a PLC to allow operation and maintenance personnel to monitor and control a machine or process.
PLC connections for input devices such as switches and sensors and output devices, which include a variety of actuators.
An international standard that defines important PLC characteristics such as programming languages. Part 3 of this standard identifies the most common PLC programming languages. Two of these languages are Ladder diagram (LAD) programming and function block diagram (FBD) programming.
A type of device, such as a switch or sensor, that sends information to a PLC’s input points.
PLC module that connects to input devices and communicates input device signals to the PLC’s CPU.
A connection point on a PLC for an input device such as a switch or sensor.
A module for a PLC that connects to input or output devices and converts the signals from the devices into binary for the CPU.
A representation of the logic of an electrical circuit or system using common symbols. The individual lines or "rungs" connected between two vertical lines resemble a ladder.
A method for drawing electrical control diagrams. Ladder diagram PLC programming is sometimes referred to as ladder logic.
A Boolean logic function for which the output will be a logic 1 if one or more inputs is a logic 1.
A type of device that responds to signals from a PLC’s output points.
A connection point on a PLC for an output device.
programmable logic controller
PLC. A processor controlled device that uses logic-based software to provide electrical control of machines and processes.
A device, usually a personal computer, used to enter instructions into the PLC.
One complete cycle of a PLC’s cyclical operation that includes checking inputs, executing its programs, updating the status of its outputs, and performing various other required processes.
A device that detects a change in a physical condition stimulus and turns it into a signal that can be measured or recorded. Some sensors are used as PLC input devices.
The coded instructions or programs that control computer hardware functions and operations.
A type of instruction in a PLC program that times intervals or events.