Release Notes — Coldwave YUKI Block RSX1/LTE-M

First production release of the YRX1 LTE-M gateway firmware — a Modbus-RTU / BACnet-MS/TP field-bus gateway with on-device PLC-style scripting, secure boot and signed over-the-air updates.

Manufacturer: ImagineOn GmbH, Köln · Document generated from the curated public release-notes source.

1.0.02026

First production release of the YRX1 gateway firmware and the baseline of the 1.x line, developed under an IEC 62443-4-1-tailored secure development lifecycle.

Added

Modbus-RTU master with backend-curated register mapping and content-match filtering: field-bus registers are mapped to Coldwave properties, and property writes are routed back to single- or multiple-register writes on the bus.
BACnet-MS/TP master gateway for BACnet field devices.
Runtime-selectable serial mode — RS232, RS485/Modbus or RS485/BACnet — with line settings (baud rate, data bits, parity, stop bits) retained across power cycles.
On-device PLC-style scripting via the Coldwave Script VM sandbox, running in a constrained profile (no raw I/O, enforced memory cap). Scripts are delivered over the TLS-protected property channel.
LTE-M / NB-IoT connectivity through the Coldwave modem stack, with NB-IoT-preferred scanning.
Battery-backed real-time clock with automatic time-zone resolution on roaming events.
Monthly data-budget guard with a configurable cap, backend override and automatic reset on the month boundary.
Emergency property sync on power loss — a supercapacitor-backed shutdown hook drains the queued property sync before brown-out.
Secure boot and signed OTA updates — firmware images are ECDSA-P256-signed and verified by the bootloader, with anti-rollback enforced through a monotonic firmware version.

Fixed

Closed memory leaks on the error paths of the Modbus and BACnet mapping deserializers, surfaced by fuzz testing of malformed mapping data.
Hardened the mapping read and write paths against null-pointer and out-of-bounds access when processing malformed backend mapping pushes.

Security

This is the initial security-conformant baseline. Security-relevant fixes are listed under Fixed; there is no predecessor release from which issues carry over.

Quality and security assurance

The 1.0.0 image ships from a host quality pipeline enforced in CI: static analysis on security and quality rule-sets with no outstanding findings, software-composition analysis with no known critical or high-severity vulnerabilities in third-party components, unit tests, and continuous fuzzing of the mapping and Modbus parsers.

Known limitations

External RED / EN 18031-1 certification by an accredited body has not been performed for the 1.0.0 baseline; conformity is established on a self-assessment basis.
The EU Cyber Resilience Act reporting workflow is prepared. ENISA reporting obligations apply from 2026-09-11, with the full regulation applicable from 2027-12-11.