ABB TU842 3BSE020850R1

Description

Product Description

The ABB TU842 3BSE020850R1 is a Termination Unit designed for ABB’s S800 I/O system, which is a core component of the AC 800M controller and System 800xA DCS platform. This unit acts as a remote and intelligent interface point, extending the reach of the controller’s I/O by connecting to remote S800 I/O modules via a high-speed, serial fieldbus. The ABB TU842 specifically serves as a communication and power distribution hub in a distributed I/O architecture, enabling the placement of I/O racks close to field devices in harsh or distant plant areas, thereby reducing long and costly field wiring runs. For comprehensive technical data, installation manuals, and network planning guides, please visit the official product page for the ABB TU842 3BSE020850R1. The design of the ABB TU842 3BSE020850R1 facilitates flexible, reliable, and cost-effective system expansion in large-scale process automation.

Product Parameters

• Product Type: Termination Unit / Remote I/O Communication Interface.

• Ordering Code / Article Number: 3BSE020850R1.

• Model: TU842.

• Primary Function: Interfaces between a master communication module (like a CI854 in the main controller rack) and remote S800 I/O modules (e.g., AI835, DI810) via a serial link.

• Communication Protocol: Typically uses ABB’s S800 I/O Link, a proprietary, deterministic serial communication protocol for remote I/O.

• I/O Link Ports: Features connectors for the incoming and outgoing I/O Link cables, allowing for daisy-chaining of multiple termination units and I/O modules.

• Power Supply Distribution: Includes terminals for distributing the 24V DC field power to the connected S800 I/O modules mounted on the same rail.

• Mounting: Designed for DIN rail mounting. It serves as the starting point or node in a remote I/O rack, onto which other S800 I/O modules are mounted.

• Diagnostics: Equipped with status LEDs for power and I/O Link communication status.

• Configuration: The connected I/O modules are configured from the central engineering station (Control Builder M); the TU842 acts as a transparent communication gateway.

Advantages and Features

The ABB TU842 3BSE020850R1 provides significant advantages in system design and installation. Its primary benefit is the enablement of distributed I/O architecture, which drastically reduces wiring costs and complexity by locating I/O near sensors and actuators. It enhances system reliability by minimizing long wire runs that are susceptible to noise and damage. The unit allows for flexible system layout and easy future expansion by simply adding more I/O modules to the remote rack or daisy-chaining another termination unit. The ABB TU842 is built for industrial durability, ensuring stable communication in electrically noisy environments. It simplifies cabinet layout by consolidating communication and power distribution for a group of I/O modules into a single, managed point.

Application Cases in Various Fields

• Large Process Plants (Oil & Gas, Chemical): Installing a remote I/O rack with a TU842 near a distant process unit (like a tank farm or a wellhead) to connect local instruments, while the main controller is located in a centralized control room hundreds of meters away.

• Water and Wastewater Treatment: Placing remote I/O racks at various pump stations, clarifiers, or filter buildings spread across a large site, all linked back to a central SCADA system via TU842 units and fiber optic links.

• Power Plant Auxiliary Systems: Distributing I/O for boiler sootblowers, fuel handling systems, or ash silos that are located far from the main control cabinet, using the ABB TU842 as the local interface node.

• Manufacturing Facilities: Creating localized control clusters for a specific machine cell or production line segment, with the TU842 gathering all I/O data for transmission to a supervisory controller.

Comparison with Competing Products

Compared to using all local I/O modules in the main controller cabinet, the ABB TU842 enables a distributed architecture that competing PLC systems often replicate with their own remote I/O adapters (e.g., Siemens ET200SP interface module, Rockwell 1734-AENTR Point I/O adapter). The TU842 is ABB’s specific solution within the S800 I/O ecosystem. Its key differentiator is its tight integration with the AC 800M controller and the deterministic performance of the S800 I/O Link protocol. Compared to using generic Ethernet-based remote I/O, the TU842-based system can offer more predictable scan times for critical loops, though it may be less open to multi-vendor integration. Its strength lies in its purpose-built design for reliable, long-distance process I/O within the ABB domain.

Selection Suggestions and Precautions

1. System Architecture Plan: Clearly define the need for remote vs. local I/O. Use the ABB TU842 when the cost or signal integrity issues of long cable runs justify a distributed system.

2. Communication Master: The TU842 must be connected to a compatible master communication module in the controller rack (e.g., CI854, CI855). Verify compatibility and ensure the master module has sufficient capacity for the number of remote nodes.

3. I/O Link Network Planning: Adhere strictly to guidelines for maximum cable length, baud rate settings, and the maximum number of modules per link. Use repeaters or fiber optic converters for very long distances.

4. Power Calculation: The TU842 distributes power to other modules. Calculate the total 24V DC current draw of all modules in the remote rack and ensure the power supply feeding the TU842 is adequately sized.

5. Grounding and Shielding: Properly ground the termination unit and use shielded cables for the I/O Link communication to prevent noise interference. Follow ABB’s installation guidelines precisely.

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