Safety PLCs 372

actuates

To initiate the operation of a machine or device. A safety programmable logic controller actuates automatically.

aerospace

The industry that covers machines or vehicles of flight. Aerospace manufacturers may use safety PLCs to prevent damage to expensive equipment or products.

artificial intelligence

AI. A computer program with algorithms that enables a machine or computer to imitate intelligent human behavior. Artificial intelligence allows machines to perform a process with autonomy.

automatic shut-off valve

A valve that stops the flow of fluid or air without user intervention when unsafe conditions occur. An automatic shut-off valve is a potential safety PLC output device.

automotive

The manufacturing sector that produces motor vehicles and the components required to create and maintain them. The automotive industry may use safety PLCs for robots used at the facility.

boilers

A closed vessel in which water or another liquid is heated. Boilers are used to produce steam for a variety of applications and use safety PLCs to prevent overheating.

breakdown

A malfunction that prevents a component or process from operating correctly. Breakdowns usually result in maintenance expenses and lost productivity.

channels

A distribution of data between electronic components. Channels provide communication between components like memory and a controller.

chemical plants

An industrial facility that manufactures chemicals on a large scale. Chemical plants generally use safety programmable logic controllers to prevent hazardous chemicals from harming machines, people, or the environment.

chemical reactors

An enclosed vessel that contains a chemical reaction. Chemical reactors are connected to safety PLCs to detect dangerous changes in the chemical reaction.

collaborative robots

A robot that can be programmed to learn a specific task in order to assist humans. A collaborative robot is designed to interact with humans in a shared workspace.

computer vision systems

A deep learning capability that enables an artificial intelligence (AI) to detect and identify objects by recognizing visual patterns through a camera or on a screen. Computer vision systems can be useful for supervised or unsupervised machine learning but require very large amounts of visual data.

cross-fault detection

A monitoring system that identifies when short circuits occur between wires or components. Cross fault detection is necessary for safety PLCs to ensure proper functioning.

diagnostic

A set of computer instructions that helps users or technicians investigate or analyze the cause or nature of errors or failures. Diagnostics performed by a programmable logic controller can help identify potential areas of failure.

dual-channel architecture

A memory configuration that uses two separate channels to increase the rate of data transfer and reduce failure rates. Dual-channel architecture protects PLCs from failure by having two separate channels.

Emergency shutdown system

A system designed to stop processes, equipment, or facilities when imminent hazards or danger occur. Emergency shutdown systems isolate energy sources and halt operations to prevent catastrophes.

emergency stop

E-stop. The control that automatically shuts down all machine functions. An emergency stop is usually controlled by a safety PLC.

e-stops

Emergency stop. The control that automatically shuts down all machine functions. An e-stop is usually controlled by a safety PLC.

fail-safe

A response to unsafe conditions that causes systems to resort to non-dangerous states. Fail-safe may involve the closing of machine doors when a safety PLC has failed.

failure rate

The frequency with which a system or component fails. Failure rates must be monitored and tested for safety-related systems.

function blocks

A box-shaped element that contains program instructions. Function blocks contain instructions for processing input data and generating output data.

functional safety

A particular category of precautions that focuses on ensuring that electrical systems, electronics, and software fail safely. Functional safety often requires a safety programmable logic controller to ensure automatic protection during system failure.

IEC

International Electrotechnical Commission. An organization that provides conformity assessment for government and consumer organizations for all electrical, electronic, and related technologies. The IEC outlines standards for functional safety and Safety Integrated Systems.

IEC 61508

A functional safety standard that specifies design and maintenance of safety-related systems in multiple industries. IEC 61508 applies to the design and maintenance of Safety Instrumented Systems.

IEC 61511

A functional safety standard that focuses on safety-related systems in the process industry. IEC 61511 applies to industries such as food, beverage, and pharmaceutical manufacturing.

IEC 61513

A functional safety standard that focuses on safety-related systems in nuclear plants. IEC 61513 helps prevent catastrophes in nuclear industries.

IEC 62061

A functional safety standard that focuses on the design, implementation, and validation of safety-related systems in manufacturing. IEC 62061 specifies certain requirements for machines depending on the possibility of danger.

Industrial Internet of Things

IIoT. A network of physical devices used in manufacturing that contain computing systems. The Industrial Internet of Things allows devices to exchange data and automate processes with limited human intervention.

input devices

A type of field device connected to a PLC that responds to a condition and sends an electrical signal to the input module. Input devices include components such as limit switches, pushbuttons, and sensors.

interlocks

A safeguarding device that causes a machine to stop when it is out of position. Interlocks may be controlled by a safety PLC.

International Organization for Standardization

ISO. A nongovernmental organization based in Switzerland that develops and establishes standards, rules, and guidelines designed to ensure that products, processes, and services are fit for their purposes. The International Organization for Standardization publishes standards for a broad range of industries.

ISO 13849

A functional safety standard that specifies the design and implementation of safety-related systems, including software. ISO 13849 is used in North America.

ladder logic

A graphical PLC programming language that uses simple symbols to indicate the status of input and output devices. Ladder logic displays program instructions in a ladder diagram

light curtain

A field of light that stops a machine when the light is blocked by an object. Light curtains prevent mechanical parts from striking workers and equipment.

logic solver

A specialized type of programmable logic controller that monitors industrial automated systems for safety purposes. Logic solvers, also known as safety programmable logic controllers, ensure that machinery and processes operate safely by responding automatically to unsafe conditions.

machine guards

A shield or cover that is placed over hazardous areas on a machine to prevent accidental contact with body parts or to prevent debris, such as chips, from exiting the machine. Machine guards often partially cover the point of operation while allowing necessary access.

machine learning

The process that enables a digital system to analyze data in order to build predictive models and make decisions autonomously. Machine learning can help improve safety systems over time.

microprocessors

A type of integrated circuit containing a central processing unit (CPU) that is wired to separate memory chips and input and output devices that perform electronic functions. Microprocessors send processed data outputs to external control devices.

non-recurring faults

An isolated one time failure that occurs randomly due to an unpredictable event. Non-recurring faults can be harder to predict but should be accounted for, such as a power surge in a circuit.

output devices

A type of field device connected to a PLC that performs a desired action after receiving an electrical signal from the output module. Output devices include components such as motor starters, heaters, and solenoids.

performance level

PL. A measurement of a safety control system’s ability to perform safety functions. Performance levels rank a machine on its probability of failure.

personal protective equipment

PPE. Safety equipment that machine operators wear or use to prevent injury in the workplace. Personal protective equipment includes safety glasses and protective gloves.

PLC

Programmable logic controller. A processor-driven device that uses logic-based software to provide electrical control to a machine or process. PLCs can replace many physical relays and hard-wired connections in a process.

pneumatic system

A system that uses air or other gases to transmit motion to mechanical parts. Pneumatic systems with the potential for dangerous accidents require a safety PLC.

predictive maintenance

A maintenance approach that tests and monitors each machine individually in order to predict failures. In predictive maintenance, periodic readings are compared to baseline readings in order to identify problems.

pressure transducer

A device that converts variations in pressure into an analog electrical signal. Pressure transducers are a type of analog input device.

process control systems

PCSs. The computer systems, process sensors, and personnel used to process and analyze data from manufacturing operations. Process Control Systems, also known as Intelligent Manufacturing Control Systems, offer flexibility and can respond to real-time situations.

programmable logic controllers

PLCs. A processor-driven device that uses logic-based software to provide electrical control to a machine or process. Programmable logic controllers can replace many physical relays and hard-wired connections in a process.

programming

The process of entering digital information into a computer or computerized system. Programming involves the use of a machine interface and a programming language that can tell the machine what actions to perform.

random access memory

RAM. A type of temporary memory storage that allows data to be immediately stored, accessed, and changed. Random access memory is lost in the event that power is removed.

recurring faults

Repeated failures in a machine’s operation, safety circuit, or PLC logic that occur consistently or intermittently. Recurring faults may include general wear and tear or PLC troubleshooting that should be accounted for when evaluating safety.

redundancies

The duplication of critical components in a product or system. Redundancies act as a backup or fail-safe to prevent or minimize the effects of breakdowns and malfunctions.

risk assessment

A documented process that an organization uses to help plan for hazards. A risk assessment evaluates the control measures in place for dangerous activities.

safe condition

Any state of an electronic or software system that prevents chances of harm to humans, machines, or the environment. A safe condition commonly involves shutting a machine down but also includes other controls such as a robotic arm retracting.

safety critical

A system or device where malfunction could cause death or serious injury. Safety critical systems require very strict processes and setup to manage the system.

safety fencing

A type of physical barrier used to deter accidental entry into a robot's workcell. Safety fences should have signs warning of the hazards within their boundaries.

safety gates

A device that blocks off entrances and exits to dangerous locations. Safety gates may be electronic or manual.

safety input devices

A type of field device connected to a PLC that responds to safety conditions in a process and sends an electrical signal to the input module. Safety input devices include components such as switches, emergency stops, and sensors.

Safety Instrumented System

SIS. A network of hardware and software controls that respond to unsafe conditions in dangerous industries. A Safety Instrumented System uses a logic solver to sense and respond to machine conditions.

Safety Integrity Levels

SILs. A categorization that determines the required performance and dependability of safety-related systems. Safety Integrity Levels are outlined in IEC 62061.

safety laser scanners

A device that uses a controlled beam of light to detect the presence of people or unwanted objects and triggers a shutdown or alarm. Safety laser scanners are common safety input devices.

safety output devices

A type of field device connected to a PLC that performs a desired safety action after receiving an electrical signal from the output module. Safety output devices include safety relays and safety-rated contactors.

Safety PLC

Safety programmable logic controller. A specialized type of programmable logic controller that monitors industrial automated systems for safety purposes. Safety PLCs, also known as logic solvers, ensure that machinery and processes operate safely by responding automatically to unsafe conditions.

safety programmable logic controller

Safety PLC. A specialized type of programmable logic controller that monitors industrial automated systems for safety purposes. Safety programmable logic controllers, also known as logic solvers, ensure that machinery and processes operate safely by responding automatically to unsafe conditions.

safety ratings

A comprehensive measure of a device or component’s hazards or level of risk. Safety ratings are important to consult when setting up a safety system.

safety relays

An electromagnetic relay designed to open output circuits if connected equipment malfunctions or if the relay develops an internal fault. Safety relays are protective relays used with safety equipment such as emergency stop buttons or presence-sensing devices.

Safety-critical industries

A sector where system failures, errors, or malfunction can cause harm to people, the environment, or significant financial losses. Safety-critical industries must haves fail-safe operations to prevent catastrophes.

safety-rated contactors

A device that uses a small control current to energize or de-energize a load and is mechanically linked so that it can fail in a safe state. Safety-rated contactors function the same as traditional contactors, but they have additional precautions in case of failure.

sensors

A device that detects the presence or absence of an object, or certain properties of that object, and provides feedback. Common sensor applications include detecting, counting, positioning, and diverting parts on a production line and preventing the unsafe operation of a machine.

shutdown devices

A component or devices the temporarily stops a system, machine, or process. Shutdown devices include power switches, emergency stop buttons, or shutoff valves.

shutdowns

A period of time during which a machine or system is de-energized and not operating. Shutdowns interrupt production, but they are necessary for safety or to perform certain inspection and maintenance tasks.

SIL

Safety Integrity Level. A categorization that determines the required performance and dependability of safety-related systems. SILs are outlined in IEC 62061.

SIS

Safety Instrumented Systems. A network of hardware and software controls that respond to unsafe conditions in dangerous industries. An SIS uses a logic solver to sense and respond to machine conditions.

software

A program and instruction that a processor-driven device carries out. Software in a safety PLC requires special considerations.

software design

The process of defining and creating programs, instructions, interfaces, and formulas to control the action of a computer. Software design for safety-related systems is regulated.

steam turbine

A machine that produces continuous power using thermal energy. A steam turbine pressurizes hot air, which requires safety precautions, such as using a safety PLC.

switches

A control device that opens and closes contacts in a circuit. Switches are a type of field input device.

The International Electrotechnical Commission

IEC. An organization that provides conformity assessment for government and consumer organizations for all electrical, electronic, and related technologies. The International Electrotechnical Commission outlines standards for functional safety and Safety Integrated Systems.

trip devices

A component that interrupts a system or process if unsafe conditions are detected. Trip devices range significantly and are common safety PLC output devices.

two-hand controls

A device that requires an operator to use both hands to start and stop the machine. A two-hand control is used as a safety precaution and consists of pilot valves or electric push buttons.

unsafe conditions

Any state of an electronic system or software that proves hazardous to humans, machines, or the environment. Unsafe conditions trigger control mechanisms to prevent harm.

utilities

Services that provide essential needs for houses and businesses, such as water, heat, and gas. Utilities often use safety PLCs to prevent severe, dangerous breakdowns.