IEC 61496-1 vs IEC 61496-2: What Safety Light Curtain Buyers Need to Verify
IEC 61496-1 and IEC 61496-2 are complementary product-standard parts for a conventional AOPD safety light curtain. Part 1 provides the general ESPE requirements, while Part 2 adds the active opto-electronic requirements. Buyers must still verify model evidence, safeguard positioning, safety-control integration and the installed function.
Reviewed by xsz sensor | Updated
Hold the quotation when a document names only a family, omits a suffix or edition, or does not show that the declared Type covers the delivered configuration. Hold machine release when the position, stop time or installed safety function has not been validated.
| Condition | Recommendation | Evidence required | Stop boundary |
|---|---|---|---|
| A conventional AOPD light curtain is being quoted | Require both IEC 61496-1 and IEC 61496-2 evidence for the exact model. | Full model and suffix, editions, declared Type, instructions and declaration or report scope. | The evidence names only a series, a different model or an unspecified edition. |
| Type 2 or Type 4 must be selected | Base the Type on the machine risk assessment and applicable machine requirements, not price alone. | Required safety function, risk assessment, applicable Type-C standard and model declaration. | The Type is selected before the required safety performance and application are defined. |
| The light curtain position must be established | Use the applicable positioning method with real device, controller and machine stopping times. | Opening drawing, approach direction, resolution, response times and measured stop-time record. | The distance is copied from a product page or calculated without measured machine data. |
| The machine is ready for acceptance | Test field coverage, safe stop, restart prevention, fault response and bypass routes. | Written procedure, specified test piece, pass/fail limits, measured results and reviewer record. | No installed test exists or the delivered model and settings differ from the approved configuration. |
Which standards apply to an AOPD safety light curtain?
Electro-sensitive protective equipment (ESPE) is the broad family of non-contact protective equipment addressed by the IEC 61496 series. It is intended to detect a person or part of a person as part of a safety-related system.
Active opto-electronic protective device (AOPD) is an ESPE technology that uses active optical radiation and a receiver to create a detection field. A conventional transmitter-and-receiver safety light curtain is a common AOPD example.
That product therefore needs the general ESPE layer in Part 1 and the AOPD-specific layer in Part 2. An ordinary photoelectric sensor may also emit and receive light, but that does not make it suitable for personnel safeguarding.
Buying rule: do not accept the phrase "IEC 61496 compliant" by itself. Ask which part, edition, exact model and AOPD Type are included in the evidence.
What does IEC 61496-1 cover?
IEC 61496-1:2020 specifies general requirements for the design, construction and testing of non-contact ESPE intended to detect persons or parts of persons in a safety-related system. It is used with a subsequent sensing-technology part and does not select the detection-zone dimensions or position for a particular machine hazard.
For document review, confirm the exact edition, product identity, intended use, safety interface and declared operating limits.
What does IEC 61496-2 add for an AOPD?
IEC 61496-2:2020 specifies particular design, construction and test requirements for ESPE using AOPDs. Its public scope covers active optical radiation from 400 nm to 1,500 nm and does not select the detection-zone position for a particular machine hazard.
For document review, confirm the exact AOPD model, declared Type, detection capability, optical limits, response data and model-specific restrictions.
What is the practical difference between IEC 61496-1 and IEC 61496-2?
The difference is scope, not quality level. Part 1 is the general ESPE layer; Part 2 is the AOPD technology layer. A conventional light curtain normally needs both.
| Buyer question | IEC 61496-1:2020 | IEC 61496-2:2020 |
|---|---|---|
| What role does it play? | General requirements and tests for non-contact ESPE. | Particular requirements for ESPE using AOPDs. |
| What should supplier evidence show? | Exact edition, product identity, intended use, general safety interface and declared limits. | Exact AOPD model, declared Type, detection capability, optical limits and model-specific data. |
| Does it set mounting distance? | No. It does not select the field position for a particular hazard. | No. It does not define field disposition relative to the machine hazard. |
| Does it certify the complete machine? | No. It addresses the ESPE product layer. | No. It addresses the AOPD product layer. |
How are Part 1 and Part 2 different from Type 2, Type 4 and PL/SIL?
Standard parts, AOPD Type and machine safety performance answer three different questions. Keep all three visible in the quotation and approval record.
| Term | What it identifies | What still needs verification |
|---|---|---|
| IEC 61496-1 / IEC 61496-2 | The general ESPE and AOPD-specific standard layers. | Exact edition, model, declaration or test scope and limitations. |
| AOPD Type 2 / Type 4 | The protective-device category and related performance requirements. | Model-specific Type evidence; do not infer Type 4 from a Part 2 claim. |
| PL or SIL target | A machine safety-function or safety-control-system target. | Sensor, logic, wiring, outputs, actuators, architecture, diagnostics and validation. |
Do not infer Type 4 from Part 2, or whole-machine PL e/SIL 3 from Type 4. Verify each claim at its own level. Read the separate Type 2 vs Type 4 safety light curtain guide when the device category is still open.
What does IEC 61496 compliance not prove?
IEC 61496 evidence can support the protective-device review. It does not, by itself, prove that the delivered model matches the evidence or that the completed machine safety function is correctly designed and validated.
| It does not prove... | What must be checked separately | Stop boundary |
|---|---|---|
| The installed position or separation distance is correct. | Hazard location, approach direction, reach-over and reach-around routes, resolution, response times and the applicable positioning method. | Do not release the design without a documented position calculation and physical check. |
| The machine's actual stopping time meets the design input. | Measured stopping behavior under justified test conditions, including controller and final-element response. | Do not rely on a catalogue estimate or an unverified machine value. |
| The complete safety function achieves the required PL or SIL. | Risk-based target, architecture, logic, wiring, outputs, actuators, diagnostics, failure response and validation. | Do not treat a Type 4 device declaration as a whole-machine PL e or SIL 3 result. |
| The delivered model is the model covered by the evidence. | Manufacturer, complete model, suffix, firmware or parameter set, label and report or certificate scope. | Do not approve a family-level match when a suffix or configuration changes the covered product. |
| The installed machine behaves safely. | Protective-field tests, safe stop, reset and restart prevention, fault response, bypass routes and retained results. | Do not release the machine without an installed functional test and defined pass/fail limits. |
Related standards do different jobs: IEC 62046:2026 addresses the selection, positioning, configuration and commissioning of sensitive protective equipment in industrial applications, including ESPE from the IEC 61496 series, and is intended for use with ISO 13855:2024. ISO 12100:2010 supports risk assessment, while ISO 13849-1:2023 or IEC 62061:2021 with applicable amendments supports safety-related control design. A Type-C machinery standard, national adoption or local law may add application requirements.
Which light curtain data should you define before comparing models?
Start with the safety function, not the housing size. A 30 mm resolution is meaningful only after you know which body part must be detected, what access routes exist and how quickly the machine can stop.
Type, resolution, protective height and range
Define the risk-based Type, the body part to detect, the opening to cover and the real transmitter-to-receiver distance. Include mounting tolerance and nearby surfaces that may affect alignment.
Response time, OSSD interface and optional functions
Record the model-specific response time, safety input compatibility, OSSD test behavior, reset, external device monitoring, muting and blanking requirements. Optional functions change the application and validation boundary.
Use the guides to compare 14 mm, 30 mm and body-protection resolution and to understand OSSD safety outputs before freezing the product specification.
What evidence should the supplier provide for the exact model?
A strong supplier file lets purchasing, engineering and safety reviewers trace each important claim to the product that will actually be delivered.
Which fields must match across the supplier file?
Use one exact product identity as the key for the review. A claim is not closed until the quotation, product label, technical file and conformance evidence can all be traced to that identity.
| Check | Required match | Hold approval when... |
|---|---|---|
| Exact model | Manufacturer and complete model code on the quotation, label and documents. | A document names only a family or a different model. |
| Suffix | Every safety-relevant option or suffix is included in the evidence scope. | The delivered suffix is absent or its effect is unexplained. |
| IEC 61496-1 edition | The applicable edition is stated for the exact covered product. | The claim omits the edition or cites an unmatched product. |
| IEC 61496-2 edition | The applicable AOPD-specific edition is stated for the exact covered product. | Only a broad "IEC 61496" claim is provided. |
| Declared Type | Type 2 or Type 4 is supported by model-specific evidence. | Type appears only in marketing copy or is inferred from Part 2. |
| Datasheet and manual | Current revisions cover the ordered configuration, wiring and permitted functions. | The manual revision, model range or option coverage cannot be matched. |
| Declaration, certificate or report | Issuer, document number, date, covered variants and limitations are identifiable. | A certificate image is cropped, undated or lacks traceable scope. |
| Technical performance | Resolution, protective height, range and response time resolve to the exact model. | Values are copied from a family table without a model mapping. |
| OSSD and safety interface | Output behavior, test pulses, reset, EDM and compatible safety input are documented. | The machine interface is assumed from wire colors or a generic diagram. |
| Firmware and configuration | Safety-relevant settings, optional functions and parameter state are controlled. | The delivered setup can change response or detection behavior without review. |
| Change control | Notification and reapproval triggers cover optical, electronic, firmware and manufacturing changes. | The supplier cannot explain how an approved configuration will be maintained. |
Illustrative document review
When should a Type 4 quotation remain on hold?
This fictional example uses the placeholder model AOPD-30-1200-T4-M only to demonstrate the review method. It is not an xsz sensor model, customer case, certificate or test result.
| Review item | Supplier file | Decision |
|---|---|---|
| Quotation and label | Both identify AOPD-30-1200-T4-M. | Pass Product identity matches at this layer. |
| Part 1 and Part 2 | The declaration cites IEC 61496-1:2020 and IEC 61496-2:2020 but covers only the "AOPD-30 family." | Hold The exact suffix coverage is not stated. |
| Declared Type | Type 4 appears in the brochure; the declaration and report scope do not identify the Type. | Hold Do not infer Type 4 from the model code or Part 2 claim. |
| Certificate scope | The certificate lists AOPD-30-1200-T4 but not the -M suffix. | Hold Obtain written evidence that -M is covered or safety-neutral. |
| Response time | A family datasheet lists 14 ms for the base model; no mapping is supplied for -M. | Hold The value is not yet traceable to the delivered configuration. |
| Release decision | The supplier has not closed the three evidence gaps above. | Do not approve yet Request exact scope, Type evidence and model-specific response data. |
How should you validate the light curtain on the machine?
Set the inputs before installation
Freeze the exact model and settings. Document the hazard, access direction, required detection capability, protective height, controller and actuator response, measured machine stop time and positioning method.
Test the installed safety function
- 1Inspect the field and access routes
Check alignment, protected height, side gaps, reach-over, reach-around and any opening not covered by the field.
- 2Interrupt the field
Use the specified test piece at relevant positions and verify the expected OSSD and machine response.
- 3Verify the safe stop
Measure the actual stopping behavior under justified conditions and confirm the separation-distance inputs.
- 4Check restart and fault behavior
Verify reset location, restart prevention, feedback, wiring faults, diagnostics and final switching devices.
- 5Retain the evidence
Record model, settings, drawings, measured values, test conditions, result, reviewer and revalidation triggers.
Stop the approval when the product identity, document scope or installed test cannot be matched. A family brochure or undated screenshot does not close that evidence gap.
What should a safety light curtain RFQ and acceptance test include?
"Need a 30 mm light curtain" describes one parameter. A useful RFQ defines the machine, access, detection, timing, interface, evidence and acceptance boundary.
What can you copy into a minimum RFQ?
Replace the bracketed fields with machine data. Do not ask the supplier to select a Type or mounting position when the risk assessment and application inputs are still missing.
Subject: Safety light curtain RFQ - [machine / project] Machine and hazard - Machine type and hazardous motion: [ ] - Task, operating modes and required safe state: [ ] - Access direction and opening drawing: [attach] - Destination market and applicable machine standard: [ ] Required protective device - Required AOPD Type based on the machine risk assessment: [Type 2 / Type 4 / review needed] - Body part to detect and required resolution: [ ] mm - Protective height: [ ] mm - Transmitter-to-receiver operating range: [ ] m - Maximum device response time allowed by the design: [ ] ms - Environment: [temperature / ingress / vibration / washdown / optical conditions] Safety interface and functions - Safety relay or PLC and OSSD input details: [ ] - Reset and external device monitoring (EDM): [ ] - Muting, blanking, cascade or other configured functions: [ ] Evidence required for the exact quoted model and suffix - IEC 61496-1 edition and covered model scope - IEC 61496-2 edition and covered model scope - Declared AOPD Type and model-specific evidence - Current datasheet, manual and wiring / OSSD information - Declaration, certificate or test report with issuer, number, date, scope and limitations - Resolution, protective height, range and response-time mapping - Firmware / configuration identification and change-control process Acceptance information - Proposed test piece and field-test method: [ ] - Required stop, restart and fault checks: [ ] - Pass / fail limits and records to be supplied: [ ]
Who closes the remaining application evidence?
The supplier can propose a product and provide exact-model evidence. The machine builder or responsible integrator must still confirm positioning, measured stopping behavior, control integration and the completed safety function. Record those responsibilities before order release.
Questions buyers still ask about IEC 61496
Do safety light curtains need both IEC 61496-1 and IEC 61496-2?
For a conventional safety light curtain that is an AOPD, buyers should normally verify exact-model evidence for both. IEC 61496-1 provides the general ESPE requirements, while IEC 61496-2 adds the AOPD-specific requirements. Hold approval if only a broad "IEC 61496 compliant" claim is provided.
Is IEC 61496-2 the same as Type 4?
No. IEC 61496-2 is the AOPD-specific standard part; Type 2 and Type 4 are device categories within the applicable framework. A Part 2 claim does not identify Type 4. Verify the declared Type and its evidence for the exact model and suffix.
Does IEC 61496 specify safety light curtain mounting distance?
IEC 61496-1 and IEC 61496-2 do not select the detection-zone position for a specific machine hazard. Positioning requires the machine risk assessment, approach and opening data, device and control response times, measured machine stop time, and the applicable positioning and machinery requirements.
Does a Type 4 safety light curtain automatically achieve PL e?
No. Type 4 describes the AOPD device category; PL e applies to the complete safety function or safety-related control system. The final result depends on the sensor, logic, wiring, outputs, actuators, architecture, diagnostics and validation.
What documents should a supplier provide for IEC 61496 compliance?
Request the exact model and suffix, applicable IEC 61496-1 and IEC 61496-2 editions, declared Type, current datasheet and manual, declaration/certificate/test report scope, response time, resolution, protective height, range, OSSD information, firmware or configuration identification, and change-control terms. Do not approve until material claims trace to the delivered configuration.
Choose the guide that matches the uncertainty still open in your safety light curtain selection or validation.
- Safety Light Curtains - review the product category after defining the safety function and application data.
- What Is a Safety Light Curtain? - understand the device and its role in machine access protection.
- Type 2 vs Type 4 - separate the AOPD equipment category from the standard part number.
- Light Curtain Resolution - connect detection capability with the protected body part.
- Installation Distance - review stop time, approach, resolution and field position.
- OSSD Safety Outputs - check safety input compatibility and dual-channel behavior.
- Muting vs Blanking - understand how optional functions change protection and validation.
Reference documents used to verify this guide
- IEC 61496-1:2020 official product record - general ESPE requirements, test scope and application boundary.
- IEC 61496-2:2020 official product record - AOPD-specific scope and exclusions.
- IEC 62046:2026 official product record - selection, positioning, configuration and commissioning of sensitive protective equipment used to detect people in industrial machinery applications.
- ISO 12100:2010 official product record - machinery risk assessment and risk reduction principles.
- ISO 13849-1:2023 official product record - safety-related parts of control systems.
- ISO 13855:2024 official product record - positioning and dimensioning of safeguards.
- IEC 62061:2021 official product record - functional safety of safety-related control systems; the IEC record also identifies the consolidated 2021+AMD1:2024 version.
Scope of this article: this page summarizes public official records and application principles. It does not reproduce or replace the controlled standards text, national adoption, machine instructions, contract requirements or qualified safety validation.
What should you send before selecting a safety light curtain?
Send the real machine and access information so the proposed device can be reviewed against the application, not only against one product dimension.
- Machine and hazardous motion
- Opening drawing and access direction
- Body part to detect and resolution
- Protective height and operating range
- Measured machine stop time
- Safety relay or PLC and OSSD input
- Reset, EDM, muting or blanking needs
- Environment and destination market