Pilz describes classic and modular safety relays alongside configurable small safety controllers. The right architecture depends on the required safety functions, supported inputs and outputs, system limits and machine risk assessment.
Safety relays and configurable safety controllers are safety-rated control products, but product architecture and capabilities vary. Pilz describes classic and modular safety relay families alongside configurable small controllers. This chart is a comparison checklist, not a design determination.
Architecture comparison
| Design question | Safety relay | Configurable safety controller |
|---|---|---|
| Product example from Pilz | PNOZ safety relays and modular myPNOZ | PNOZmulti 2 small controller |
| Configuration approach | Select the relay functions and modules offered by the exact model | Configure supported safety functions in the manufacturer’s software environment |
| Capacity | Check the exact model’s safety inputs, outputs and functions | Check the base unit and compatible expansion modules for the exact system |
| Diagnostics and changes | Confirm the device’s indicators and supported configuration options | Confirm supported diagnostics, software version and change controls |
Pilz’s product descriptions distinguish a compact standalone option, a modular safety relay and a scalable configurable small controller. A particular PNOZmulti 2 base unit is published with eight freely configurable safe inputs and four safe semiconductor outputs; other product variants have different capacities.
Before selecting a device
- Complete the machine risk assessment and identify each required safety function.
- List every safety input, output, reset condition and diagnostic need.
- Compare required performance level or SIL with the exact device and system documentation.
- Check expansion, response time, environmental limits and approved wiring examples.
- Validate the implemented safety functions and keep the design records current.
Work with a qualified machinery safety professional for risk assessment, design and validation. See our light curtains vs safety scanners comparison and machine safety planning.
Sources
Common questions
Is a safety controller the same as a standard PLC?
This comparison concerns safety-rated products. Use the safety documentation for the exact controller and do not assume a standard PLC performs a safety function.
When does a machine need a configurable safety controller?
The required functions and architecture come from the machine risk assessment and the selected system's safety documentation.
Who should validate a machine safety design?
A qualified machinery safety professional should carry out or review the risk assessment and validation.