KATS Updates PLC Certification: TSN Timestamp ≤1μs Required

Seoul, May 12, 2026 — The Korean Agency for Technology and Standards (KATS) has officially released the revised KS C IEC 61131-3 v3.0 standard, introducing a mandatory requirement for Time-Sensitive Networking (TSN) timestamp accuracy in programmable logic controllers (PLCs). Effective November 1, 2026, all PLCs seeking KS certification must achieve inter-port time synchronization error of no more than ±1 microsecond under 100 Mbps TSN network conditions. The update directly affects procurement eligibility for automation control systems in high-precision manufacturing sectors—including semiconductor fabrication facilities and battery production lines—in South Korea.

Event Overview

On May 12, 2026, KATS published KS C IEC 61131-3 v3.0, amending the national implementation of IEC 61131-3 to include Clause 7.4.2.3, which specifies a hard limit of ±1 μs on TSN timestamp precision for certified PLCs operating at 100 Mbps. The clause applies to all new KS certification applications submitted on or after November 1, 2026; legacy certifications remain valid until renewal or revision, but no grandfathering is granted for new deployments in regulated facilities.

Industries Impacted

Direct Trading Enterprises: Exporters and importers of industrial automation equipment targeting the Korean market must now verify TSN timestamp compliance prior to customs clearance and KS application. Non-compliant units risk rejection at the certification stage, delaying market entry by an estimated 8–12 weeks per model—particularly critical for vendors supplying OEMs with just-in-time delivery requirements.

Raw Material Procurement Enterprises: Suppliers of timing ICs, high-stability oscillators, and TSN-capable PHY transceivers face increased demand scrutiny. Buyers are now requesting traceable test reports validating sub-microsecond jitter performance under real-world thermal and EMI conditions—not just datasheet specifications—making material qualification cycles longer and more resource-intensive.

Manufacturing Enterprises (OEMs & System Integrators): Domestic PLC manufacturers and automation system builders must redesign firmware timing stacks and hardware timestamping circuits to meet the ±1 μs bound. This includes revising clock domain crossing logic, implementing tighter PTP (IEEE 802.1AS-2020) profile alignment, and adding hardware-assisted timestamp capture at MAC layer—raising BOM cost by approximately 9–14% per unit, according to preliminary vendor estimates.

Supply Chain Service Providers: Certification consultants, test laboratories accredited under KOLAS (Korea Laboratory Accreditation Scheme), and conformity assessment bodies must upgrade their TSN validation setups to support traceable, sub-microsecond measurement against NIST-traceable time sources. Labs without calibrated 10 GbE+ TSN analyzers capable of <500 ns resolution will be unable to issue valid test reports for KS v3.0 submissions.

Key Considerations and Recommended Actions

Verify TSN timestamp architecture early—not just conformance

Compliance requires demonstrating end-to-end timestamp accuracy across all ports under load, not merely passing static PHY-level tests. Enterprises should commission pre-certification validation using synchronized multi-channel oscilloscopes or dedicated TSN analyzers before initiating formal KS application.

Review firmware update pathways for legacy models

Some existing PLC platforms may achieve compliance via firmware updates—but only if hardware supports hardware timestamping offload. Companies must audit their product roadmaps to distinguish between software-fixable and hardware-bound limitations.

Align procurement contracts with KS v3.0 timelines

Procurement agreements signed before November 2026 should explicitly define liability for rework or replacement if delivered units fail post-November certification audits—especially for projects tied to Korean government-backed smart factory subsidies.

Editorial Perspective / Industry Observation

Observably, this is not merely a technical tightening but a strategic signal: KATS is synchronizing domestic industrial standards with South Korea’s national roadmap for AI-driven fabs and gigafactories, where deterministic communication latency directly impacts yield prediction accuracy and closed-loop process control. Analysis shows that while the ±1 μs threshold aligns with current IEEE 802.1CM recommendations for motion control, it exceeds typical requirements in automotive or general discrete manufacturing—suggesting targeted enforcement in capital-intensive, high-value-add segments. From an industry perspective, the regulation is better understood as a de facto quality gate for next-generation process automation infrastructure, rather than a generic interoperability measure.

Conclusion

This revision marks a consequential step toward hardening real-time determinism in Korea’s industrial control ecosystem. Rather than representing incremental change, it reflects an institutional commitment to embedding metrological-grade timing into foundational automation hardware—a shift with long-term implications for global PLC vendors’ R&D priorities and regional supply chain resilience.

Source Attribution

Official notice issued by the Korean Agency for Technology and Standards (KATS), KS C IEC 61131-3:2026 Amendment 1 (v3.0), published May 12, 2026; accessible via the KATS Standards Portal (https://www.kats.go.kr/eng/standard). Additional guidance documents—including test methodology annexes and transition timelines—are scheduled for release by August 2026. Continuous monitoring is advised for updates to KOLAS-accredited lab requirements and potential harmonization efforts with IEC SC65C working groups.