SAFETY RELAYS and safety PLCs
August 23 2024 | Blog Post, Venus Automation
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.
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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
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.
safety RElays (DOLD vs wieland vs reer)
At Venus, we offer a range of different safety relays from DOLD, Wieland and ReeR. The DOLD UG6970 is 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 ONE is 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.
| Part Number | Supply Voltage | Contacts | Item Number |
| UF 6925.02 | 24 V DC | 2 NO Contacts | 0068316 |
| UF 6925.22 | 24 V DC | 2 NO + 1 NC Contacts | 0067558 |
| UF 6925.03 | 24 V DC | 3 NO | 0067556 |
| Part Number | Supply Voltage | Contacts | Item Number |
| UG 6970.04 | 24 V DC | 2 NO Contacts | 0065426 |
| Model | Product Number | Article Number | Supply Voltage | Number of Outputs |
| Dold - Control Unit | BH 5911.22 | 055532 | DC 24 V | 2 NO contacts, 1 NC contact |
| BH 5911.3 | 055531 | DC 24 V | 3 NO contacts |
| Part Number | Ordering Code | Supply Voltage | Terminals | Outputs |
| SNA 4043K-A | R1.188.1810.0 | 24 V AC/DC | Screw Terminals | 3NO+1NC, 230VAC 6A |
| SNA 4043K-A | R1.188.1830.0 | 115-120 V AC | Screw Terminals | 3NO+1NC, 230VAC 6A |
| SNA 4043K-A | R1.188.1840.0 | 230 V AC | Screw Terminals | 3NO+1NC, 230VAC 6A |
| SNA 4043K-C | R1.188.1940.0 | 24 V AC/DC | Push-in Terminals | 3NO+1NC, 230VAC 6A |
| SNO 4043K-C | R1.188.5000.0 | 230 V AC | Push-in Terminals | 3NO+1NC, 230VAC 6A |
| SNA 4043KM-A | R1.188.3250.0 | 24 V AC/DC | Screw Terminals | 3NO+1NC, 230VAC 6A |
| SNA 4043KE-A | R1.188.3810.0 | 24 V AC/DC | Screw Terminals | 3NO+1NC, 230VAC 6A |
| SNA 4043KE-C | R1.188.3820.0 | 24 V AC/DC | Push-in Terminals | 3NO+1NC, 230VAC 6A |
| Part Number | Ordering Code | Supply Voltage | Terminals | Outputs |
| SNA 4044K-A | R1.188.1860.0 | 24 V AC/DC | Screw Terminals | 4NO+1NC, 230VAC 6A |
| R1.188.1880.0 | 115-120V AC | Screw Terminals | 4NO+1NC, 230VAC 6A | |
| R1.188.1890.0 | 230 V AC | Screw Terminals | 4NO+1NC, 230VAC 6A | |
| SNA 4044K-C | R1.188.1960.0 | 24 V AC/DC | Push-in Terminals | 4NO+1NC, 230VAC 6A |
| SNA 4044KM-A | R1.188.1480.0 | 24 V AC/DC | Screw Terminals | 4NO+1NC, 230VAC 6A |
| SNA 4044KM-C | R1.188.3410.0 | 24 V AC/DC | Push-in Terminals | 4NO+1NC, 230VAC 6A |
| Model | Time range | Product Number | Supply Voltage | Terminals |
| SNE 4004K | - | R1.188.0590.0 | 24 VDC | Screw Terminals |
| SNE 4004K-C | - | R1.188.1980.0 | 24 VDC | Push-in Terminals |
| SNE 4004KV-A | 0.5s | R1.188.0460.0 | 24 VDC | Screw Terminals |
| 1s | R1.188.0470.0 | 24 VDC | Screw Terminals | |
| 2s | R1.188.0480.0 | 24 VDC | Screw Terminals | |
| 3s | R1.188.0490.0 | 24 VDC | Screw Terminals | |
| SNE 4004KV-C | 0.5s | R1.188.2410.0 | 24 VDC | Push-in Terminals |
| 1s | R1.188.2420.0 | 24 VDC | Push-in Terminals | |
| 2s | R1.188.2430.0 | 24 VDC | Push-in Terminals | |
| 3s | R1.188.2440.0 | 24 VDC | Push-in Terminals |
| Part Number | Ordering Code | Terminals | Supply Voltage | Outputs | Safety Applications |
| SNO 4062K-A | R1.188.0700.2 | Screw Terminals | 24V AC/DC | 2NO+1NC, 230VAC 6A | E-Stop, Safety Gate, Light curtains |
| SNO 4062KM-A | R1.188.0720.2 | Screw Terminals | 24V AC/DC | 2NO+1NC, 230VAC 6A | E-Stop, Safety Gate, Light curtains |
| SNO 4062K-C | R1.188.2000.0 | Push-in Terminals | 24V AC/DC | 2NO+1NC, 230VAC 6A | E-Stop, Safety Gate, Light curtains |
| Part Number | Ordering Code | Supply Voltage | Synchr. Time | Terminals |
| SNO 4083KM-A | R1.188.3580.0 | 24 V DC | 1.5 s | Screw Terminals |
| SNO 4083KM-A | R1.188.3590.0 | 115-120V AC | 1.5 s | Screw Terminals |
| SNO 4083KM-C | R1.188.3600.0 | 24 V DC | 1.5 s | Push-in Terminals |
| SNO 4083KM-C | R1.188.3610.0 | 115-120V AC | 1.5 s | Push-in Terminals |
| SNO 4083KM-A | R1.188.3840.0 | 24 V DC | 0.5 s | Screw Terminals |
| SNO 4083KM-A | R1.188.3830.0 | 115-120V AC | 0.5 s | Screw Terminals |
| SNO 4083KM-C | R1.188.3850.0 | 24 V DC | 0.5 s | Push-in Terminals |
| SNO 4083KM-C | R1.188.3860.0 | 115-120V AC | 0.5 s | Push-in Terminals |
| Model | Product Number | Contacts | Outputs | Operating Voltage | Adjustment Range | Terminals |
|---|---|---|---|---|---|---|
| SNS 4084K-A | R1.188.3640.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.5 – 99Hz | Screw Terminals |
| SNS 4084K-C | R1.188.3650.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.5 – 99Hz | Push-in Terminals |
| SNS 4074K-A | R1.188.3620.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.1 – 9.9Hz | Screw Terminals |
| SNS 4074K-C | R1.188.3630.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.1 – 9.9Hz | Push-in Terminals |
| SNS 4084K-A | R1.188.3480.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.5 – 99Hz | Screw Terminals |
| SNS 4084K-C | R1.188.3490.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.5 – 99Hz | Push-in Terminals |
| SNS 4084K-A | R1.188.3660.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.1 – 9.9Hz | Screw Terminals |
| SNS 4084K-C | R1.188.3670.0 | 4 Inputs | 4 Safe OSSD outputs and 2 OSSD outputs | 24 VDC | 0.1 – 9.9Hz | Push-in Terminals |
| Part Number | Ordering Code | Supply Voltage | Terminals |
| SNT 4M63K-A | R1.188.1050.0 | 24 V AC/DC | Screw Terminals |
| R1.188.1060.0 | 115-120V AC | Screw Terminals | |
| R1.188.1070.0 | 230 V AC | Screw Terminals | |
| SNT 4M63K-C | R1.188.2390.0 | 24 V AC/DC | Push-in Terminals |
| Part Number | Ordering Code | Outputs | Terminals | Supply Voltage |
| SNV4063KL-A | R1.188.0620.0 | 2NO, 1NO Off-delay 0.15-3 seconds, 230VAC 6A | Screw Terminal | 24VDC |
| R1.188.0640.0 | 2NO, 1NO Off-delay 1.5-30 seconds, 230VAC 6A | Screw Terminal | 24VDC | |
| R1.188.4100.0 | 2NO, 1NO Off-delay 7.5-150 seconds, 230VAC 6A | Screw Terminal | 24VDC | |
| SNV4063KL-C | R1.188.2010.0 | 2NO, 1NO Off-delay 0.15-3 seconds, 230VAC 6A | Push-in Terminal | 24VDC |
| R1.188.3900.0 | 2NO, 1NO Off-delay 1.5-30 seconds, 230VAC 6A | Push-in Terminal | 24VDC |
| Part Number | Order Code | Terminals |
Supply Voltage
|
|
SNZ 4052K-A
|
R1.188.0530.1 | Screw Terminal | 24 AC/DC |
| R1.188.0940.1 | Screw Terminal | 115 - 120 AC | |
| R1.188.0950.1 | Screw Terminal | 230 V AC | |
| SNZ 4052K-C | R1.188.2020.0 | Push-in Terminal | 24 AC/DC |
| Part Number | Order Code | Category | Terminals | Contacts |
| AD SRE4 | 1330913 | Cat. 4 | Screw Terminal | 3 NO +1 NC (5A at 250 VAC) |
| AD SRE4C | 1330914 | Cat. 4 | Clamp Terminal | 3 NO +1 NC (5A at 250 VAC) |
| AD SRE3 | 1330911 | Cat. 3 | Screw Terminal | 2 NO (6A at 250 VAC) |
| AD SRE3C | 1330912 | Cat. 3 | Clamp Terminal | 2 NO (6A at 250 VAC) |
| Part Number | Order Code | Start/Restart | Terminals | Contacts |
| SR E4 | 1330803 | Either Automatic or Manual | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR E4 C | 1330808 | Either Automatic or Manual | Clamp Terminal | 2 NO (6A at 250 VAC) |
| SR E4C | 1330804 | Manual Only | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR E4C C | 1330809 | Manual Only | Clamp Terminal | 2 NO (6A at 250 VAC) |
| Part Number | Order Code | Description | Terminals | Contacts |
| SR ONE | 1330900 | Safety Interface for Safety Light Curtains | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR ONE C | 1330811 | Safety Interface for Safety Light Curtains | Clamp Terminal | 2 NO (6A at 250 VAC) |
| SR ONE M | 1330904 | Safety Interface for Safety Light Curtains, with Integrated Muting Functions | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR ONE MC | 1330812 | Safety Interface for Safety Light Curtains, with Integrated Muting Functions | Clamp Terminal | 2 NO (6A at 250 VAC) |
| Part Number | Order Code | Description | Terminals | Contacts |
| SR SELECT | 1330941 | Multifunction safety interface | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR SELECT C | 1330813 | Multifunction safety interface | Clamp Terminal | 2 NO (6A at 250 VAC) |
| Part Number | Order Code | Description | Terminals | Contacts |
| SR X | 1201710 | Safety Interface for Cat. 2 safety photocells | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR XC | 1201714 | Safety Interface for Cat. 2 safety photocells | Clamp Terminal | 2 NO (6A at 250 VAC) |
| SR XM | 1201711 | Safety Interface for Cat. 2 safety photocells, with integrated Muting functions | Screw Terminal | 2 NO (6A at 250 VAC) |
| SR XMC | 1201715 | Safety Interface for Cat. 2 safety photocells, with integrated Muting functions | Clamp Terminal | 2 NO (6A at 250 VAC) |
Featured Products
safety PLCs (wieland vs reer)
Among the various different PLCs that exist, Venus offers the samos® PRO from Wieland and the MOSAIC Safety Controller from ReeR. The samos® PRO from Wieland is a modular safety controller programmed using the intuitive, license-free samos® PLAN 6 software, which includes features like automatic hardware configuration and integrated simulation. It supports various communication protocols such as PROFINET and Ethernet/IP, making it suitable for a wide range of industrial applications. The MOSAIC Safety Controller from ReeR is known for its modular and expandable design, allowing it to manage multiple safety functions across different machines. It supports field-bus interfaces like ModBus TCP and Profinet RT, and complies with SIL 3 and PL e standards, making it ideal for complex safety control systems. Both controllers offer advanced diagnostics and scalability, catering to diverse safety requirements in industrial environments.
| Model | Safety Applications | Features | Supply Voltage | Ordering Code |
| SP-COP2-EN-A | Safety control, muting | Ethernet for Programming only | 24VDC | R1.190.1210.0 |
| SP-COP2-ENI-A | Safety control, muting, monitoring, HMI | Industrial Ethernet (Ethernet/IP, Profinet, MODBUS/TCP) | 24VDC | R1.190.1310.0 |
| SP-COP2-EN-P-A | Safety control, muting, presses, analogue input | Ethernet, press/analogue library | 24VDC | R1.190.1230.0 |
| SP-COP2-ENI-P-A | Safety control, muting, monitoring, HMI, presses, analogue input | Industrial Ethernet, press/analogue library | 24VDC | R1.190.1330.0 |
| Model | Product Number | Safety Applications | Supply Voltage | Outputs |
| M1 | 1100000 | Estop, Two-hand buttons, Safety gate, Light curtain, Scanner, Enable switch | 24VDC | 8 Safety Inputs 2 Pair OSSD Safety Outputs |
| M1S | 1100003 | Estop, Two-hand buttons, Safety gate, Light curtain, Scanner, Enable switch | 24VDC | 8 Safety Inputs 4 Single OSSD Safety Outputs (2 Pairs) |
| M1S COM | 1100006 |
Estop, Two-hand buttons, Safety gate, Light curtain, Scanner, Enable switch. Fieldbus Interface built-in protocols: Ethernet IP (default), EtherCAT, PROFINET, MODBUS TCP |
24VDC | 8 Safety Inputs 4 Single OSSD Safety Outputs (2 Pairs) |
| Model | Product Number | Supply Voltage | Inputs | Compatibility |
| MA2 | 1100026 | 24VDC | 2 channels configurable 0-20mA, 4-20mA or 0-10V | M1S only |
| MA4 | 1100025 | 24VDC | 4 channels configurable 0-20mA, 4-20mA or 0-10V | M1S only |
| MA2C | 1100126 | 24VDC | 2 channels configurable 0-20mA, 4-20mA or 0-10V | M1S only |
| MA4C | 1100125 | 24VDC | 4 channels configurable 0-20mA, 4-20mA or 0-10V | M1S only |
| Model | Product Number | Supply Voltage | Relay Output Options | Signal Outputs |
| MR2 | 1100040 | 24VDC | 2 relays 2NO+1NC, 240VAC 6A | - |
| MR4 | 1100041 | 24VDC | 4 relays 4NO+2NC, 240VAC 6A | - |
| MOR4 | 1100042 | 24VDC | 2 channels 2NO+2NC, 240VAC 6A | - |
| 4 channels 1NO+1NC, 240VAC 6A | ||||
| MOR4S8 | 1100043 | 24VDC | 2 channels 2NO+2NC, 240VAC 6A | 8 Signal Outputs |
| 4 channels 1NO+1NC, 240VAC 6A |
| Model | Product Number | Supply Voltage | I/O | Compatibility |
| MI8O2 | 1100010 | 24VDC | 8 inputs, 4 test outputs, 2 OSSD pairs with EDM and Start/Restart interlock, 2 signal outputs | M1/M1S |
| MI8O4 | 1100011 | 24VDC | 8 inputs, 4 test outputs, 4 single OSSD (or 2 pairs) with EDM and Start/Restart interlock, 4 signal outputs | M1S only |
| MI8 | 1100020 | 24VDC | 8 inputs, 4 test outputs | M1/M1S |
| MI16 | 1100021 | 24VDC | 16 inputs, 4 test outputs | M1/M1S |
| MI12T8 | 1100022 | 24VDC | 12 inputs, 8 test outputs | M1/M1S |
| MO2 | 1100030 | 24VDC | 2 OSSD pairs with EDM and Start/Restart interlock, 2 signal outputs | M1/M1S |
| MO4 | 1100031 | 24VDC | 4 OSSD pairs with EDM and Start/Restart interlock, 4 signal outputs | M1/M1S |
| Model | Product Number | Supply Voltage | Inputs | Encoder |
|---|---|---|---|---|
| MV1H | 1100071 | 24 VDC | 1 or 2 PNP/NPN proximity switches | HTL incremental encoder |
| MV1S | 1100072 | 24 VDC | 1 or 2 PNP/NPN proximity switches | Sin/Cos incremental encoder |
| MV1T | 1100070 | 24 VDC | 1 or 2 PNP/NPN proximity switches | TTL incremental encoder |
| MV1TB | 1100086 | 24 VDC | 1 or 2 PNP/NPN proximity switches | TTL incremental encoder |
Featured Products
Conclusion
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!
Click to view our safety Relay product Range
Click to view our safety PLC product Range
