PROFIsafe Safety Protocol

What Is PROFIsafe?

PROFIsafe is a safety communication protocol that allows safety-related and standard automation data to operate within the same network architecture.

Rather than requiring a separate network specifically for safety communication, PROFIsafe adds safety mechanisms that help detect communication errors and verify the integrity of safety-related data.

These mechanisms help a safety system:

• Detect corrupted or incorrect data
• Identify missing or delayed messages
• Verify that data comes from the correct safety device
• Monitor communication timing
• Respond predictably when communication faults occur

The result is reliable communication between safety devices and the safety controller within a PROFINET-based system.

Why PROFIsafe Matters in Functional Safety

Functional safety is designed to reduce risk when equipment, components, or control systems do not behave as expected.

In automated machinery, the safety system may depend on motion information such as position, speed, or direction to determine whether equipment is operating within defined safe limits.

PROFIsafe provides a way to communicate that safety-related information within a PROFINET architecture while helping detect faults that could compromise the integrity of the data.

This can be especially important for safety functions involving:

• Safe speed monitoring
• Safe position monitoring
• Safe direction monitoring
• Safe motion
• Safe stopping functions

The specific safety functions available depend on the encoder, controller, system architecture, and application.

PROFINET vs PROFIsafe

PROFINET

Standard PROFINET provides industrial Ethernet communication between automation components such as PLCs, drives, sensors, and other devices.

It is designed for standard machine control and automation communication but is not inherently safety-rated.

PROFIsafe

PROFIsafe adds safety-related communication mechanisms that allow safety data to be transmitted within a compatible PROFINET architecture.

These additional safeguards help monitor data integrity, timing, device identity, and communication faults so that the safety controller can respond appropriately if valid safety information is no longer available.

In many systems, this allows standard control information and safety-related information to coexist within the same overall network architecture.

PROFIsafe and Motion Feedback

Encoders can be important inputs to a functional safety system because they provide information about how a machine or axis is moving.

Depending on the encoder and system design, safety-related encoder feedback can provide information used to monitor:

• Position
• Speed
• Direction
• Movement

A PROFIsafe-compatible safety encoder communicates this safety-related motion information to a compatible safety controller.

If the controller detects an unsafe condition or determines that valid safety data is no longer available, the safety system can initiate the response defined by the machine's safety design.

Note: Supported safety functions, certifications, and safety levels depend on the specific encoder, controller, system architecture, and implementation.

Planning for PROFIsafe 

If PROFIsafe is part of your machine design, consider the safety architecture early in the development process.

Questions to evaluate include:

• What safety functions does the machine require?
• What SIL or Performance Level must the safety system achieve?
• Is the machine control architecture based on PROFINET?
• Which safety PLC or controller will be used?
• Does the application require safe position, speed, direction, or other motion information?
• Is single-turn or multi-turn position feedback required?
• What mechanical configuration is needed?
• What environmental conditions will the encoder experience?
• What diagnostics and fault responses are required?

Considering these requirements early can help simplify device selection, integration, validation, and documentation.

PROFIsafe FAQ

EPC's PROFIsafe Encoder