Industry Trends in Redundant I/O Connectivity
Industrial automation increasingly demands reliable communication between control systems and field devices. Redundant configurations minimize downtime in critical processes. The ABB TU849 termination unit addresses this need by supporting redundant Optical ModuleBus Modems TB840/TB840A.
Introducing the ABB TU849 Termination Unit
The TU849 is a module termination unit (MTU) designed for redundant modem setups. It provides a single electrical ModuleBus connection and dual power supply inputs, one for each modem. This passive unit mounts on a standard DIN rail and uses a mechanical latch for secure locking.
Four mechanical keys, two per modem position, prevent insertion of incorrect module types. Each key offers six positions, enabling 36 different configurations. Operators can adjust these settings easily with a screwdriver.
Technical Specifications and Performance
The TU849 operates on a 24 V d.c. power input with a range of 19.2 to 30 V. It distributes up to 1.5 A at 5 V and 1.5 A at 24 V on the ModuleBus. Power dissipation is 2.5 W, and the unit accepts solid or stranded wires from 0.2 to 2.5 mm² (24–12 AWG) with a recommended torque of 0.5 Nm.
Rated insulation voltage is 50 V, with a dielectric test voltage of 500 V a.c. The unit measures 124 mm wide, 186.5 mm high (including latch), and 47 mm deep, weighing 0.45 kg. It operates from 0 to +55 °C (approvals issued for +5 to +55 °C) and stores from -40 to +70 °C.
Applications in Modern Manufacturing
In process industries such as oil and gas or chemical plants, redundant communication links are essential for safety and uptime. The TU849 connects two TB840/TB840A modems to non-redundant I/O, ensuring continuous data flow even if one modem fails. Its dual power supply connections further enhance reliability.
For discrete manufacturing, the unit supports cluster addressing via a rotary switch (settings 1 to 7). This allows multiple termination units to coexist on the same ModuleBus, simplifying system architecture. The DIN rail mounting and mechanical keying reduce installation errors.
Real-World Application Example
Consider a water treatment facility that requires uninterrupted communication between its PLC and remote I/O racks. By deploying the TU849 with redundant TB840/TB840A modems, the facility maintains data integrity during modem maintenance or failure. The dual power inputs ensure the unit stays operational even if one supply drops.
Compatibility and Integration
The TU849 works with the ABB TB840 and TB840A Optical ModuleBus Modems. It uses the ModuleBus communication protocol and supports line redundancy. The unit accepts vertical or horizontal mounting and is CE marked, with safety certifications including EN 61010-1 and UL 61010-1.
Hazardous location approvals include cULus Class 1 Zone 2 and ATEX Zone 2. Marine certificates from ABS, BV, DNV-GL, and LR are also available. The unit complies with EU, UAE, and CN RoHS directives and WEEE Directive 2012/19/EU.
Frequently Asked Questions About the TU849
What is the primary function of the TU849?
The TU849 serves as a module termination unit for redundant TB840/TB840A modems. It provides a single electrical ModuleBus connection and dual power supply inputs, enabling non-redundant I/O connectivity.
How does the mechanical keying work on the TU849?
The unit features four mechanical keys, two for each modem position. Each key has six positions, allowing 36 different configurations to prevent insertion of wrong module types. Operators change settings with a screwdriver.
What are the mounting options for the TU849?
The TU849 mounts on a standard DIN rail using a mechanical latch that locks and grounds the unit. It supports both vertical and horizontal mounting orientations. For vertical mounting, the maximum ambient temperature is 40 °C.
Why Choose CtrlTechDaily
CtrlTechDaily offers the ABB TU849 termination unit with expert support and reliable supply. We help you select the right components for your automation needs. Contact us for availability and lifecycle status before ordering.
