Industry Trends in Redundant ModuleBus Solutions
Modern industrial automation increasingly demands high availability and fault tolerance. Redundant communication links help minimize unplanned downtime in critical processes. The ABB TU849 addresses this need by supporting redundant Optical ModuleBus Modem configurations.
As factories adopt Industry 4.0 principles, reliable data transmission between controllers and I/O becomes essential. The TU849 provides a passive termination unit that simplifies redundant setups without adding active components that could fail.
Introducing the ABB TU849 Termination Unit
The TU849 is a module termination unit (MTU) designed for redundant configuration of Optical ModuleBus Modem TB840/TB840A. It connects TB840/TB840A to non-redundant I/O while offering dual power supply connections for each modem.
This passive unit includes a rotary switch for cluster address setting (1 to 7) and mechanical keying to prevent insertion of wrong module types. The TU849 mounts on a standard DIN rail and uses a mechanical latch for secure locking and grounding.
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 ModuleBus current at maximum 5 V 1.5 A and 24 V 1.5 A, with a total power dissipation of 2.5 W.
Acceptable wire sizes include solid and stranded conductors from 0.2 to 2.5 mm² (24 to 12 AWG), with a recommended torque of 0.5 Nm. The unit measures 124 mm wide, 186.5 mm high including latch, and 47 mm deep, weighing 0.45 kg.
Environmental ratings include an operating temperature range of 0 to +55 °C (approvals issued for +5 to +55 °C) and storage from -40 to +70 °C. The TU849 carries IP20 ingress protection and multiple safety certifications including CE, cULus Hazardous Location Class 1 Zone 2, and ATEX Zone 2.
Applications in Modern Manufacturing
In process industries such as oil and gas or chemical plants, redundant communication links are critical for safety and continuous operation. The TU849 enables engineers to build a redundant Optical ModuleBus network with dual power supplies, ensuring that a single modem failure does not interrupt I/O communication.
For discrete manufacturing lines, the TU849 supports vertical or horizontal mounting on DIN rails, fitting easily into existing control cabinets. Its mechanical keying with 36 different combinations prevents module misinsertion, reducing commissioning errors.
Comparison with Similar Termination Units
The TU849 differs from the TU848 in its I/O configuration. While the TU848 connects TB840/TB840A to redundant I/O, the TU849 connects them to non-redundant I/O. Both units offer dual power supply connections and individual power inputs for each modem.
For applications requiring redundant I/O paths, the TU848 is the appropriate choice. For systems where the I/O side is non-redundant but the ModuleBus link needs redundancy, the TU849 provides a cost-effective solution without over-engineering.
Integration with Existing Networks
The TU849 uses the ModuleBus communication protocol, making it compatible with ABB's AC 800M and other controllers that support this protocol. It accepts a single electrical ModuleBus connection and provides two positions for TB840/TB840A modems.
Line redundancy is built into the design, allowing the system to maintain communication even if one modem or its power supply fails. The rotary switch sets the cluster address from 1 to 7, enabling multiple termination units on the same bus.
Frequently Asked Questions About the TU849
What is the difference between TU848 and TU849?
The TU848 connects TB840/TB840A to redundant I/O, while the TU849 connects them to non-redundant I/O. Both support dual power supplies and individual power connections for each modem.
What certifications does the TU849 hold?
The TU849 carries CE marking, electrical safety certifications per EN 61010-1 and UL 61010-1, hazardous location approvals (cULus Class 1 Zone 2, ATEX Zone 2), and marine certificates from ABS, BV, DNV-GL, and LR.
Can the TU849 be mounted in any orientation?
Yes, the TU849 supports both vertical and horizontal mounting on a standard DIN rail. For vertical mounting, the maximum ambient temperature is 40 °C (104 °F), compared to 55 °C (131 °F) for horizontal mounting.
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