DESCRIPTION:
Optima has just released the August 2026 T:LAN OS Update. This major release introduces a lightweight native MQTT v3.1.1 telemetry subsystem along with critical networking stack enhancements, OS kernel improvements, and firmware fixes. For more information, please refer to the associated OS release notes or check out the WHAT’S NEW section below.
T:lan OS Details
VERSION: 1.06.98A
RELEASE: C3426
BUILD: 8537
RELEASE DATE:
August 18, 2026
IMAGE NAMES:
NETPRO
Revision
File
Size
Rev.3x
npe4x...1698AC3426... .rom
483,746
Rev.4x
np44x...1698AC3426... .rom
554,856
OCP
Revision
File
Size
Rev.3x
oce4x...1698AC3426... .rom
356,468
Rev.4x
oc44x...1698AC3426... .rom
368,570
COMPATIBILITY:
This release is suitable for the following models/units:
Optima T:LAN NetPro e42/e44, Rev.3x,
Optima T:LAN NetPro e42/e44, Rev.4x,
Optima T:LAN OCP e40, Rev.3x,
Optima T:LAN OCP e40, Rev.4x,
REQUIREMENTS:
For best results, use in conjunction with Optima Remote Commander Client (RCC) Version 3.13.0 (or newer).
RELEASE HIGHLIGHTS & ARCHITECTURAL OVERVIEW:
1. New Subsystem: MQTT v3.1.1 Telemetry & Event Client
A lightweight, dedicated MQTT Client has been fully integrated into the T:LAN operating system for continuous telemetry reporting and event dispatching:
Core MQTT Implementation:
Dynamic CONNECT packet construction supporting standard username and password authentication.
In-flight Packet Identifier (PID) queue management with duplicate handling (DUP flag tracking) and PID aging mechanisms.
Robust connection state machine equipped with exponential retry backoff, Keep-Alive timers, and automated PINGREQ / PINGRESP exchanges.
Last Will and Testament (LWT) integration for real-time online/offline status reporting.
Telemetry & Remote I/O (RIO) Event Dispatching:
Integrated directly with the RIO alarms subsystem to broadcast real-time relay state changes and discrete alarm transitions as compact, JSON-formatted telemetry payloads over MQTT.
User Configuration & Management:
Dedicated MQTT configuration screens and real-time status monitors added to the console interface.
Full non-volatile memory (NVM) parameter persistence for MQTT broker hostnames, port assignments, credentials, and custom topic hierarchy definitions.
2. TCP/IP Stack & Networking Layer Fixes
Comprehensive refinements across the embedded networking stack deliver enhanced throughput, stability, and packet integrity:
TCP Protocol Engine:
Complete fine-tuning of Karn's Algorithm and Jacobson's retransmission timeout (RTO) calculations to optimize link adaptability over high-latency and jitter-prone connections.
Fixed TCP pseudo-header checksum calculation and endianness bugs that could impact select network routers and gateways.
Improved TCP sequence number tracking, immediate ACK response generation, and dynamic window update handling, effectively eliminating TCP stalls and duplicate ACKs.
Resolved connection freeze and lockup conditions affecting active TELNET streams and multi-packet bulk data transfers.
IP / UDP / Ethernet Layers:
Corrected IP and UDP edge-case checksum calculations under fragmented and boundary conditions.
Low-level operating system enhancements ensure deterministic multitasking and unified terminal sessions:
Multitasking & System Variables:
Added dedicated task scheduler entries and execution loops for background MQTT processing and asynchronous network handling without impacting real-time I/O scanning loops.
Allocated optimized system variable structures, buffer descriptors, state control blocks, and configuration flags for security scratchpads, cryptographic routines, and MQTT message queues.
Serial & Console Management:
Unified session state management between Local Console ports, Telnet virtual terminals, and crypto-secured sessions.
Corrected terminal flow control handling, prompt redirection behaviors, and screen formatting routines.
Fixed Terminal Flow Control, Screen Formatting, and Prompt Redirection Routines
NOTE:
All T:LAN/RIO Embedded OS ROM files are covered by the Optima Embedded Software License Agreement. By using the provided T:LAN/RIO Embedded OS ROM file you acknowledge that you have read and understood the Optima Embedded Software License Agreement, and you agree to be bound by it.
Authorized users can now download the latest T:LAN OS firmware files via the Optima Cloud Storage.
OPTIMA RECOMMENDED T:LAN OS UPDATE STEPS TO BE TAKEN BEFORE 2026Perform T:LAN OS Update To A Level Above BN7655
T:LAN OS Versions prior to BN7655 contain a pre-calculated table to determine the DST Start and DST End dates (North America/Canada DST Rules). To guarantee proper DST adherence, Optima recommends that all customers upgrade the T:LAN firmware running in their production units before the current table based data reaches its end. The table based method expires in 2026. The new algorithm based method to determine the DST start and end dates helps extend the service life of a T:LAN unit until at least 2037.
Perform T:LAN OS Update To BN7798 Or Above
Optima recommends that all T:LAN units that have been in production networks for close to 20 years (or more) be regularly checked for the presence of the 'RAM:FILE Re-Initialized' and/or 'RTC Battery Failed' entries in the T:LAN EVENT LOG.
T:LANs are equipped with a lithium battery on its main printed circuit board. The battery offers a data retention span of nine years (with the unit powered down) and has a total life expectancy of more than 20 years (powered unit). A reliable retention of the T:LAN configuration settings cannot be assumed once the battery is spent. Depleted batteries must be replaced. Please refer to “T:LAN Battery Replacement Procedure” in the T:LAN USER GUIDE for instructions on how to properly and safely replace the lithium battery.
Customers are also encouraged to update to BN7798 or higher before performing the proactive maintenance step [N]PA $ADBC3243 in order to fully test the RTC battery.
For more details, refer to the release notes titled:
4000-T200068A TLAN NetPro OPERATING SYSTEM SOFTWARE RELEASE NOTES NOV 2025.
4000-T200069A TLAN NetPro OPERATING SYSTEM SOFTWARE RELEASE NOTES AUG 2026.
