What is a Safety PLC
Features of Safety PLCs:
✅Redundancy & Self-Checking: Uses dual processors or redundant
architectures for fault detection.
✅ Fail-Safe Operation: Automatically brings the system to a safe state in case of
failure.
✅ Regulatory Compliance: Meets SIL (Safety Integrity Level) and PL (Performance Level) requirements.
✅ Integrated Safety Logic:
Can process
both standard automation and safety functions in a single system.
✅ Advanced Diagnostics: Provides real-time monitoring, fault detection, and logging
for troubleshooting.
✅ Communication with Standard PLCs: Supports safety protocols like PROFIsafe, CIP Safety, and Safety over Ether CAT.
Why Do We Use a Safety PLC?
🔹 Personnel & Equipment Safety
– Prevents accidents by monitoring safety
devices (emergency stops, light curtains).
🔹 Cost-Effective & Scalable – Reduces
wiring, installation time, and maintenance
costs in large systems.
🔹 Flexible &
Easily Programmable – Replaces traditional
hardwired safety relays with a configurable and expandable system.
🔹 Improved System
Integration – Works with SCADA, HMI, and standard
PLCs
for seamless
automation.
🔹 Reliable & Efficient –
Ensures fail-safe shutdowns, reducing downtime and increasing productivity.
Applications of Safety PLCs:
🏭 Manufacturing & Automation – Machine guarding, robotic safety.
⚡ Power Plants
– Generator and turbine protection.
🛢 Oil & Gas – Fire and gas detection, emergency shutdowns.
🚗 Automotive – Robotic welding,
assembly line safety.
🍽 Pharmaceutical & Food – Conveyor interlocks, cleanroom safety.
Popular Safety PLC Brands:
🔹 Siemens SIMATIC Safety PLC
🔹 Allen-Bradley Guard Logix
🔹 Schneider Electric
Modicon Safety
PLC
🔹 PILZ PNOZmulti Safety Controller
🔹 Omron NX Safety PLC
Conclusion:
A Safety
PLC is a crucial component in modern industrial automation, providing a programmable, reliable, and cost-effective
solution for safety-critical
applications. By integrating advanced diagnostics, fail-safe operation, and seamless communication, it ensures compliance with safety
standards while improving efficiency and
system reliability.
Siemens offers Safety PLCs under the SIMATIC
S7 series for
failsafe automation applications. Below is a list of Safety CPUs across different S7 series:
Popular Siemens SIMATIC Safety PLC
S7-300 F (Failsafe) CPUs (Discontinued, but still in use)
1.
CPU 315F-2 DP
2.
CPU 317F-2 DP
3. CPU 319F-3 PN/DP
S7-400 F (Failsafe) CPUs (High-end, discontinued in favor of S7-1500)
1.
CPU 414F-3 PN/DP
2.
CPU 416F-2
3.
CPU 416F-3 PN/DP
4. CPU 417F-3 PN/DP
S7-1200F (Failsafe) CPUs (Compact and cost-effective)
1.
CPU 1212FC
2.
CPU 1214FC
3.
CPU 1215FC
4. CPU 1217FC
S7-1500F (Failsafe) CPUs (Modern high-performance safety PLCs)
1.
CPU 1511F-1 PN
2.
CPU 1513F-1 PN
3.
CPU 1515F-2 PN
4.
CPU 1516F-3 PN/DP
5.
CPU 1517F-3 PN/DP
6.
CPU 1518F-4 PN/DP
Popular Guard Logix Safety
PLC Models
1. Compact Guard Logix (5069 Series) – Compact & Scalable
🔹 Ideal for small to mid-sized safety applications.
🔹 Supports SIL 2 / PLd and SIL 3 / PLe with redundancy.
🔹 Integrated EtherNet/IP for seamless communication.
🔹 Models:
• 5069-L306ERS2 (SIL 2 / PLd)
• 5069-L3100ERMS2 (SIL 3 / PLe)
2. ControlLogix GuardLogix (5580 Series) – High Performance
🔹 Best for large, high-speed safety applications.
🔹 Supports SIL 3 / PLe with redundancy.
🔹 Fast execution times and high memory capacity.
🔹 Models:
• 1756-L82ES (SIL 3 / PLe)
• 1756-L85ES (High-end model, SIL 3 / PLe)
3. GuardLogix 5570 (Legacy Series)
🔹 Older generation but still widely used in industrial automation.
🔹 Supports SIL 3 / PLe applications.
🔹 Models:
• 1756-L72S (SIL 3)
• 1756-L73S (Higher capacity)
Schneider Electric Modicon Safety
PLC Models
1. Modicon M580 Safety
PLC (PAC - Process Automation Controller)
🔹 High-end safety
PLC for process & machine safety
applications.
🔹 Supports SIL 3 (IEC 61508) and PLe (ISO 13849-1).
🔹 Integrated CIP Safety over Ethernet/IP & Modbus TCP/IP.
🔹 Redundant architecture for high availability.
🔹 Key Model:
· BMEP584040S (M580 Safety CPU, SIL 3)
2. Modicon M340 Safety PLC
🔹 Compact safety PLC for medium-sized automation systems.
🔹 Supports SIL 2 / PLd
applications.
🔹 Works with Safety I/O modules and
integrates with Modbus TCP/IP.
🔹 Key Model:
· BMXCPS4022S (Safety CPU, SIL 2)
3. Modicon X80 Safety I/O Modules
🔹 Compatible with M580 & M340
platforms.
🔹 Local &
Remote I/O support
for distributed architectures.
🔹 Used for E-stops, light curtains, door interlocks, and safety sensors.
🔹 Popular Models:
· BMXSDI1602S (16-point Safety Digital Input Module)
BMXSDO0802S (8-point Safety Digital Output Module)
Popular Models of PNOZmulti Safety Controllers
1. PNOZ m B0 Series
(Compact Base Units)
🔹 Standalone or Expandable for medium-sized applications.
🔹 Supports up to 8 expansion modules.
🔹 Models:
· PNOZ m B0 – Standard version with 20 inputs, 4 safety outputs.
· PNOZ m B0.1 – Advanced version with Ethernet-based diagnostics.
2. PNOZ m B1 Series (High Performance)
🔹 More memory & higher processing power for complex safety applications.
🔹 Requires at least one I/O expansion module.
🔹 Model:
· PNOZ m B1 – More flexible and modular compared to B0.
3.
PNOZmulti 2 (Next-Gen
Safety Controller)
🔹 More compact, faster
processing, and enhanced
diagnostics.
🔹 Supports SIL 3 / PL e applications.
🔹 Models:
· PNOZ m B0.2 – Improved version of PNOZ m B0 with higher processing
speed.
· PNOZ m B1.2 – Advanced version of PNOZ m B1, ideal for complex machine safety.
Popular Models of Omron NX Safety PLCs
1. NX-SL5000 (Standard Safety CPU)
🔹 Handles small to mid-sized safety applications.
🔹 Supports 128 safety I/O points.
🔹 EtherCAT and FSoE (FailSafe over EtherCAT) support.
2. NX-SL5500 (Advanced Safety CPU)
🔹 For complex safety applications with higher performance.
🔹 Supports up to 254 safety I/O points.
🔹 Faster processing speed for time-critical operations.
3. NX-SIH400 & NX-SOD400 (Safety I/O Modules)
🔹 NX-SIH400 – Safety input module (4 inputs).
🔹 NX-SOD400 – Safety output module (4 outputs).
🔹 Used for emergency stops, interlocks, and safety sensors.
