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DLMS UA and STS Association Sign Landmark Liaison Agreement to Advance Smart Meter Interoperability in 2026
Summary: The DLMS User Association and STS Association signed a liaison agreement in January 2026, bridging prepaid token technology with the DLMS/COSEM data model, while Edition 12 of the Green Book and new water meter profiles further expand the interoperable metering ecosystem.
The smart metering standards landscape experienced a seismic shift in early 2026, as two of the most influential organizations in metering interoperability — the DLMS User Association (DLMS UA) and the Standard Transfer Specification (STS) Association — formalized their cooperation through a liaison agreement. This landmark accord, signed in January 2026, aims to bridge prepaid token technology with the widely adopted DLMS/COSEM data model, enabling true dual-standard interoperability for the global metering ecosystem.
DLMS UA & STS Association Liaison Agreement
The liaison agreement marks a pivotal step in the evolution of interoperable, secure, and future-ready metering systems. By aligning STS token technology with the DLMS/COSEM framework, the collaboration bridges the gap between legacy prepaid infrastructure and next-generation smart metering. Key objectives include:
| Objective | Description | Beneficiary |
|---|---|---|
| Interoperability | Align STS credit tokens with DLMS/COSEM data model | Utilities with dual-standard deployments |
| Prepayment integration | Strengthen smart prepayment capabilities | Prepaid meter markets in Africa, India |
| Legacy protection | Enable modernization while preserving existing investments | Utilities with STS-compliant estates |
| Secure data exchange | Robust data protection under DLMS/COSEM framework | All smart meter stakeholders |
The relevant standards bridge includes IEC 62055-41 (STS meter functionality), IEC 62055-51 (STS numeric token carrier), STS 101-2 (STS token transfer over DLMS), STS 201-2 (STS Attributes COSEM interface class), and IEC 62056-5-3 (DLMS application layer protocol).
DLMS/COSEM Green Book Edition 12 Released
The DLMS User Association published the Green Book Edition 12 (DLMS UA 1000-2 Ed.12 V1.0) on May 28, 2025. This significant update to the DLMS/COSEM architecture and protocols specification introduces key technical changes including:
| Edition | Release Date | Key Changes |
|---|---|---|
| Ed. 9 | 2014 | DataNotification, general protection, block transfer |
| Ed. 10 | 2017 | Enhanced security, efficiency improvements |
| Ed. 11 | 2021 | Push communication, firmware update optimization |
| Ed. 12 | 28 May 2025 | STS alignment, water meter profile, enhanced cybersecurity |
Additionally, the DLMS White Book Edition 2 (1002 Ed.2) was released on April 20, 2026, further expanding the COSEM interface class library and companion specifications.
Water Smart Meter (WSM) Generic Companion Profile
DLMS UA also announced the release of the Water Smart Meter (WSM) Generic Companion Profile (GCP), extending the DLMS/COSEM framework to water metering applications. Key features include:
The WSM GCP operates independently of telecommunication technologies, ensuring secure, reliable, and interoperable data exchange across diverse network environments. It incorporates robust data protection mechanisms under the DLMS/COSEM framework and provides metrology-relevant data sharing for legal metrology compliance. DLMS UA's rigorous certification process reduces the need for expensive, bespoke certification platforms.
Brazil's INMETRO Mandates Carbon Data Embedding
In a move that could reshape smart meter compliance globally, Brazil's INMETRO added carbon data embedding requirements to its smart meter regulation. The amendment requires that all smart meters subject to mandatory conformity assessment in Brazil must:
| Requirement | Standard Reference |
|---|---|
| Native IPv6 address allocation | Within DLMS/COSEM protocol stack |
| Carbon footprint data fields | Annex D of IEC 62056-62:2026 |
| CBAM alignment | EU Carbon Border Adjustment Mechanism |
Enforcement begins September 1, 2026, applying to all smart meter models intended for the Brazilian market. This requirement may influence other regulators in Latin America and beyond to adopt similar carbon-tracking mandates.
IEC 62052-31:2024 Safety Requirements
The IEC published EN IEC 62052-31:2024, specifying general safety requirements and associated tests for type testing of directly connected electricity metering equipment. This standard addresses product safety concerns including fire resistance, electrical insulation, and mechanical integrity, and is being adopted across European national standards bodies.
Implications for the Industry
The convergence of STS and DLMS/COSEM standards through the liaison agreement represents mature recognition that prepayment and data exchange standards are complementary rather than competing. For utilities deploying both prepaid and postpaid metering systems, this means reduced integration complexity, lower certification costs, and the ability to standardize on a single communication protocol across mixed meter estates. The combined effect of Green Book Edition 12, the WSM profile, and INMETRO's carbon data mandate signals that the smart metering ecosystem is evolving toward unified, secure, and environmentally-conscious interoperability.
Source: DLMS User Association (dlms.com); STS Association (sts.org.za); STS-DLMS Liaison Agreement Announcement; TechFocus24.com; iTeH Standards Catalog (standards.iteh.ai); ChinaAlloySteel.com; soocia.com.