Whats the Difference? Safety Relays vs Safety PLCs.
1
Oct
Whats the Difference? Safety Relays vs Safety PLCs.
SAFETY RELAYS and safety PLCs
An introduction to Relays and Plcs
In industrial workplaces, safety relays and safety PLCs are crucial for preventing accidents and ensuring employee safety. Safety relays manage safety-critical inputs and outputs, like emergency stop buttons, to stop machinery when hazards are detected. These devices are vital in industries such as manufacturing and automotive. Safety systems, including controllers, relays, and sensors, protect workers and machinery by monitoring safety functions and ensuring compliance with standards. The samos® PRO, with its intuitive samos® PLAN 6 software, and MOSAIC safety controllers, known for their expandable and modular design, are key solutions for managing multiple safety functions and enhancing safety control systems.
Key differences and features
The primary difference between a safety relay and a safety PLC lies in their complexity and functionality. Safety relays are simpler, electromechanical devices designed for specific safety functions, such as emergency stops or guard monitoring, and are well-suited for straightforward, single or two-step safety applications. In contrast, safety PLCs are more advanced and programmable, capable of handling complex safety tasks by using redundant microprocessors, which eliminate the need for multiple safety relays. Safety PLCs are ideal for applications requiring integrated and flexible safety solutions across multiple machines or processes.
Functionality | Simple devices for opening/closing circuits
Complexity | Suitable for basic control tasks
Programming | No programming required
Scalability | Limited scalability; each relay performs a specific function
Diagnostics | Minimal diagnostics, typically visual indicators
Applications | Used for simple on/off control, e.g., lighting or motor starting
Costs | Generally, less expensive
In industrial workplaces, safety relays and safety PLCs are crucial for preventing accidents and ensuring employee safety. Safety relays manage safety-critical inputs and outputs, like emergency stop buttons, to stop machinery when hazards are detected. These devices are vital in industries such as manufacturing and automotive. Safety systems, including controllers, relays, and sensors, protect workers and machinery by monitoring safety functions and ensuring compliance with standards. The samos® PRO, with its intuitive samos® PLAN 6 software, and MOSAIC safety controllers, known for their expandable and modular design, are key solutions for managing multiple safety functions and enhancing safety control systems.
Functionality | Complex devices for automating industrial processes
Complexity | Capable of handling complex control tasks
Programming |Requires programming using specialized software
Scalability |Highly scalable with expansion modules and programmable functions
Diagnostics |Advanced diagnostics and monitoring features
Applications |Used in complex automation systems, e.g., manufacturing lines
Costs | More costly due to advanced capabilities
Functionality | Simple devices for opening/closing circuits
Complexity | Suitable for basic control tasks
Programming | No programming required
Scalability | Limited scalability; each relay performs a specific function
Diagnostics | Minimal diagnostics, typically visual indicators
Applications | Used for simple on/off control, e.g., lighting or motor starting
Costs | Generally, less expensive
In industrial workplaces, safety relays and safety PLCs are crucial for preventing accidents and ensuring employee safety. Safety relays manage safety-critical inputs and outputs, like emergency stop buttons, to stop machinery when hazards are detected. These devices are vital in industries such as manufacturing and automotive. Safety systems, including controllers, relays, and sensors, protect workers and machinery by monitoring safety functions and ensuring compliance with standards. The samos® PRO, with its intuitive samos® PLAN 6 software, and MOSAIC safety controllers, known for their expandable and modular design, are key solutions for managing multiple safety functions and enhancing safety control systems.
Functionality | Complex devices for automating industrial processes
Complexity | Capable of handling complex control tasks
Programming |Requires programming using specialized software
Scalability |Highly scalable with expansion modules and programmable functions
Diagnostics |Advanced diagnostics and monitoring features
Applications |Used in complex automation systems, e.g., manufacturing lines
Costs | More costly due to advanced capabilities
Additional Features
Safety Relays
Emergency Stop Monitoring: Safety relays can monitor emergency stop buttons to ensure machinery stops immediately when needed.
Safety Gate Monitoring: They can monitor the status of safety gates and interlocks, ensuring that machinery operates only when gates are closed.
Two-Hand Control: Some safety relays are designed to require two-hand operation, which is essential for certain machinery to prevent accidental activation.
Cross Monitoring: This feature ensures that both channels of a dual-channel safety system are functioning correctly and are not short-circuited.
Automatic and Manual Start/Restart: Safety relays can be configured for automatic or manual start/restart, depending on the safety requirements of the application.
Time Delays: Some relays include time delay functions for controlled stopping of machinery.
Feedback Loop Monitoring: This ensures that external contactors or relays are functioning correctly and are in the expected state.
Force-Guided Contacts: These ensure that the contacts move together, providing a reliable indication of the relay’s status.
LED Indicators: Many safety relays have LED indicators for easy status monitoring and diagnostics.
Safety PLCs
Programmability:Safety PLCs can be programmed to handle a wide range of safety tasks, allowing for customization to specific application needs.
Redundancy: They often include redundant microprocessors to ensure reliability and prevent failures.
Integrated Safety Functions: Safety PLCs can manage multiple safety functions, such as emergency stops, safety gate monitoring, and speed control, within a single system.
Modular Design: Many safety PLCs are modular, allowing for expansion with additional input/output modules to accommodate larger or more complex systems.
Communication Interfaces: They typically support various communication protocols for integration with other systems and devices, facilitating data exchange and remote monitoring.
Diagnostic Capabilities: Safety PLCs provide detailed diagnostics and status information, which helps in troubleshooting and maintaining the system.
Compliance with Safety Standards: They are designed to meet international safety standards, ensuring that they provide a high level of safety assurance.
User-Friendly Software: Programming and configuration are often done through intuitive software interfaces, which may include features like drag-and-drop programming and simulation tools.
High-Speed Processing: Safety PLCs are capable of processing safety functions quickly to ensure rapid response to unsafe conditions.
Emergency Stop Monitoring: Safety relays can monitor emergency stop buttons to ensure machinery stops immediately when needed.
Safety Gate Monitoring: They can monitor the status of safety gates and interlocks, ensuring that machinery operates only when gates are closed.
Two-Hand Control: Some safety relays are designed to require two-hand operation, which is essential for certain machinery to prevent accidental activation.
Cross Monitoring: This feature ensures that both channels of a dual-channel safety system are functioning correctly and are not short-circuited.
Automatic and Manual Start/Restart: Safety relays can be configured for automatic or manual start/restart, depending on the safety requirements of the application.
Time Delays: Some relays include time delay functions for controlled stopping of machinery.
Feedback Loop Monitoring: This ensures that external contactors or relays are functioning correctly and are in the expected state.
Force-Guided Contacts: These ensure that the contacts move together, providing a reliable indication of the relay’s status.
LED Indicators: Many safety relays have LED indicators for easy status monitoring and diagnostics.
Programmability:Safety PLCs can be programmed to handle a wide range of safety tasks, allowing for customization to specific application needs.
Redundancy: They often include redundant microprocessors to ensure reliability and prevent failures.
Integrated Safety Functions: Safety PLCs can manage multiple safety functions, such as emergency stops, safety gate monitoring, and speed control, within a single system.
Modular Design: Many safety PLCs are modular, allowing for expansion with additional input/output modules to accommodate larger or more complex systems.
Communication Interfaces: They typically support various communication protocols for integration with other systems and devices, facilitating data exchange and remote monitoring.
Diagnostic Capabilities: Safety PLCs provide detailed diagnostics and status information, which helps in troubleshooting and maintaining the system.
Compliance with Safety Standards: They are designed to meet international safety standards, ensuring that they provide a high level of safety assurance.
User-Friendly Software: Programming and configuration are often done through intuitive software interfaces, which may include features like drag-and-drop programming and simulation tools.
High-Speed Processing: Safety PLCs are capable of processing safety functions quickly to ensure rapid response to unsafe conditions.
safety RElays (DOLD vs wieland vs reer)
At Venus, we offer a range of different safety relays from DOLD, Wieland and ReeR. The DOLD UG6970is a multifunctional safety module suitable for emergency stops, safety gates, and light curtains, complying with PL e and SIL 3 standards, and featuring adjustable safety functions with LED diagnostics. The Wieland SNV 4063KL-A is an emergency stop relay with time delay capabilities, designed for controlled stops with SIL certification, offering force-guided contacts and adjustable time ranges. The ReeR SR ONEis a safety relay with integrated muting functions, ideal for devices needing manual or automatic start/restart with EDM feedback, meeting SIL 3 and PL e standards, and providing LED status indicators. Each relay addresses specific safety needs, enhancing control in industrial applications.
Safety Interface for Cat. 2 safety photocells, with integrated Muting functions
Clamp Terminal
2 NO (6A at 250 VAC)
Featured Products
Wieland SNV 4063KL – A ReeR SR ONE
safety PLCs (wieland vs reer)
In industrial workplaces, safety relays and safety PLCs are crucial for preventing accidents and ensuring employee safety. Safety relays manage safety-critical inputs and outputs, like emergency stop buttons, to stop machinery when hazards are detected. These devices are vital in industries such as manufacturing and automotive. Safety systems, including controllers, relays, and sensors, protect workers and machinery by monitoring safety functions and ensuring compliance with standards. The samos® PRO, with its intuitive samos® PLAN 6 software, and MOSAIC safety controllers, known for their expandable and modular design, are key solutions for managing multiple safety functions and enhancing safety control systems.
Both safety relays and safety PLCs play essential roles in maintaining safe and efficient industrial operations. While safety relays provide reliable and straightforward solutions for specific safety tasks, safety PLCs offer flexibility and advanced control for complex safety requirements. Together, they form a comprehensive safety framework that protects workers, machinery, and the environment, ensuring compliance with safety standards and enhancing overall operational efficiency. As industries continue to evolve, the integration of these safety technologies will remain crucial in fostering safe and productive workplaces. Click the products below to view the offered products at Venus!
MOSAIC MV2 ExpansionMOSAIC MV1 ExpansionMOSAIC Output ExpansionMOSAIC Input ExpansionMOSAIC Analog InputMOSAIC Fieldbus ModulesMOSAIC Expansion UnitsMOSAIC Safety PLCMOSAIC MZEROSAMOS Compact PRO BasicSAMOS Compact PRO Plus
Conclusion
Choosing between a safety relay and a safety PLC depends on the complexity of the application and safety requirements. For straightforward, single-function safety measures like emergency stop monitoring, safety relays offer a simple and cost-effective solution. However, when managing multiple safety functions across interconnected machinery, programmable safety controllers such as the samos® PRO or MOSAIC safety controller provide greater flexibility, scalability, and diagnostics.
While traditional relays are reliable, industries increasingly lean towards integrated safety PLCs for their ability to streamline complex safety processes and reduce wiring. Both solutions play an essential role in industrial safety, ensuring compliance with stringent regulations and protecting workers and equipment. Selecting the right system involves balancing cost, expandability, and ease of implementation. Whether opting for modular safety relays or advanced programmable logic controllers, implementing a well-designed safety system is crucial to fostering a safe and efficient workplace.
