ABB TU849 3BSE042560R1 S800 I/O Redundant Module Termination Unit

Product Overview

The ABB TU849 (3BSE042560R1) functions as the critical communication and power interface for redundant S800 I/O configurations. This Module Termination Unit (MTU) provides the physical housing and electrical backbone for redundant TB840 or TB840A Cluster Modems. By integrating dual power inputs and supporting line redundancy, the TU849 ensures the I/O cluster maintains communication with the controller even during power or bus failures. We supply this unit as 100% Brand New and Original, guaranteeing maximum uptime for your mission-critical automation clusters.

Technical Specifications

The TU849 establishes a high-availability foundation with the following parameters:

Engineering Advantages

• Redundant Communication Backbone: The TU849 enables line redundancy for the Modulebus. It supports two TB840/TB840A modems simultaneously, creating a fail-safe communication path that prevents a single cable break or modem failure from dropping an entire I/O cluster.

• Dual Power Input Security: The unit accepts two independent 24V DC power feeds. This dual-supply architecture protects the I/O station against the failure of a single power supply unit (PSU), ensuring the electronics remain energized and operational during electrical maintenance or faults.

• Error-Proof Maintenance: Built-in mechanical keying with 36 different combinations prevents the insertion of incorrect module types into the MTU. This physical lockout system eliminates the risk of hardware damage during rapid field replacements or system expansions.

• High-Capacity Current Distribution: The MTU distributes up to 1.5A at both 5V and 24V to the connected I/O modules via the Modulebus. This high current capacity supports large I/O clusters without requiring additional mid-rack power injection.

• Robust Terminal Design: The screw terminals accommodate a wide range of wire sizes (up to 12 AWG) and support a recommended torque of 0.5 Nm. This secure connection method prevents intermittent signals and contact resistance in high-vibration industrial environments.

FAQs

• Does the TU849 support Hot Swap for the MTU itself?

  No. While the modules attached to an MTU often support hot swapping, the TU849 MTU is a fixed part of the station infrastructure. You must power down the cluster before removing or replacing the MTU base to avoid bus disturbances.

• Can I use a single TB840 modem with the TU849?

  Yes, the TU849 can operate with a single TB840/TB840A modem. However, the system will not provide line redundancy until you install the second modem. This allows for incremental system builds where redundancy is added later.

• What is the purpose of the 36 mechanical keys?

  These keys allow you to "code" the MTU slot. Once set, only a module with the matching key configuration can fit. This prevents a technician from accidentally plugging a different module type into a slot configured for a specific cluster modem.

• Does the 2.5W power dissipation include the modems?

  No, the 2.5W specification refers to the heat generated by the TU849 base unit itself during full load distribution. You must account for the power dissipation of the TB840 modems and I/O modules separately when calculating your cabinet's thermal load.