On June 22, 2026, TÜV Rheinland released its Functional Safety Certification Guide for SIS – Edition 2026, adding a specific documentation requirement for IEC 61511-1 SIL2 applications that use a China-brand PLC as the logic solver. For safety instrumented systems such as petrochemical emergency shutdown valve controllers and boiler interlock systems, applicants will need a TÜV-certified conformance test report for the domestic PLC communication stack covering Modbus TCP or PROFINET, with enforcement beginning in September 2026. This is worth close attention for equipment manufacturers, PLC suppliers, certification teams, procurement functions, and end users preparing safety-related projects or renewals.

What the 2026 guide now requires

The confirmed update is limited but operationally significant. TÜV Rheinland issued the 2026 edition of its SIS functional safety certification guide on June 22, 2026. Under the new guidance, any safety instrumented system applying for IEC 61511-1 SIL2 certification must provide a TÜV-certified conformance test report for the communication stack if a China-brand PLC is used as the logic solving unit.

The requirement explicitly refers to domestic PLC communication stacks for Modbus TCP and PROFINET. The summary also identifies representative application scenarios, including petrochemical emergency shutdown valve controllers and boiler interlock systems. According to the provided information, the rule is scheduled to take effect from September 2026.

Where the practical impact is likely to appear first

System integrators and safety equipment manufacturers

From an industry perspective, this group is likely to feel the impact earliest because certification submissions, technical files, and product configuration choices sit directly in their workflow. Where SIL2 projects rely on a China-brand PLC as the logic solver, communication-stack evidence becomes part of the certification path rather than a side issue. The immediate concern is whether existing project documentation and certification planning already account for this report requirement.

Domestic PLC suppliers and protocol stack providers

Analysis shows that PLC brands and related protocol-stack developers may face closer scrutiny around conformance evidence, especially for Modbus TCP and PROFINET implementations referenced in the update. The effect is not only technical but also commercial: qualification materials, support documents, and customer-facing certification readiness may become more important in pre-sales and project approval discussions.

End users in process and boiler-related applications

Operators and project owners using SIS architectures in scenarios such as petrochemical shutdown control or boiler interlocks may need to pay more attention to component selection and document completeness during procurement and acceptance. The issue is less about changing the functional purpose of the SIS and more about whether the chosen PLC route aligns with the certification evidence expected after September 2026.

Procurement and certification support functions

What deserves closer attention is the handoff between purchasing, engineering, and certification teams. If a project specifies a China-brand PLC for a SIL2 application, missing protocol-stack conformance documentation could affect submission timing, supplier communication, or delivery expectations. In practice, this makes document readiness a business issue as much as a technical one.

What companies should review now

Check whether current SIL2 projects involve China-brand PLC logic solvers

Companies preparing IEC 61511-1 SIL2 applications should first identify whether the logic solver in scope is a China-brand PLC. That basic project mapping determines whether the new requirement applies and whether existing submission packages need to be updated before the September 2026 implementation point.

Verify the availability and status of protocol-stack test documentation

Where Modbus TCP or PROFINET is involved, the key practical question is whether a TÜV-certified conformance test report for the domestic PLC communication stack is already available. If not, teams may need to clarify document status with suppliers early rather than leaving the issue until final certification review.

Separate policy wording from project execution details

Observably, the update sets a rule direction, but each project still depends on how product architecture, supplier documentation, and certification preparation come together. Companies should avoid assuming that general compliance claims are equivalent to the specific report requirement described in the guide summary.

Prepare customer and supplier communication in advance

For manufacturers and service providers, it is prudent to align sales, engineering, and certification communication. Customers may ask whether an SIS design using a China-brand PLC can proceed smoothly under the new guide. Suppliers may also need to clarify what documentation is available, what remains under preparation, and how this interacts with planned certification timing.

Why this reads as a compliance signal, not a finished market outcome

Analysis shows that the update is best understood as a concrete compliance signal rather than proof of a broad market shift on its own. The confirmed fact is the addition of a documentation requirement tied to SIL2 certification when a China-brand PLC is used as the logic solver. What remains to be observed is how widely this affects active projects, how quickly suppliers align their documentation, and whether additional clarifications emerge as the September 2026 enforcement date approaches.

It is more appropriate to understand this as a rule change with direct workflow implications for affected certification cases, while the broader commercial and competitive effects still require continued observation.

How to read this update at this stage

At this stage, the most balanced reading is that TÜV Rheinland has made communication-stack verification more explicit for a defined set of SIL2 certification scenarios involving China-brand PLCs. The significance lies in certification preparation, supplier qualification materials, and project delivery coordination, not in any confirmed restructuring of the wider automation market. For industry participants, the near-term priority is document readiness and scope checking, while the longer-term implications should be monitored through subsequent project practice and any further official clarification.

Basis of this article

This article is generated from the user-provided news title, event date, and event summary. The confirmed factual basis includes the June 22, 2026 release of TÜV Rheinland’s Functional Safety Certification Guide for SIS – Edition 2026, the stated SIL2 certification requirement for TÜV-certified conformance testing of domestic PLC communication stacks for Modbus TCP or PROFINET when a China-brand PLC is used as the logic solver, and the stated September 2026 effective timing.

For this type of industry update, relevant source categories typically include official notices, company announcements, industry association materials, authoritative media reporting, and standard-related guidance documents. A specific official source link was not provided in the input, so further verification remains necessary. Continued attention should focus on any later clarification of wording, application scope, and implementation details related to certification practice.