Configured for redundant I/O termination and communication routing in the Advant S900 I/O system, the ABB TU921S 3KDE175111L9210 (TU921S Redundant Termination Unit) provides physical termination for up to 16 I/O modules with redundancy and hot configuration functions.

Model Identification

The TU921S is identified by the following ordering references:

• Base Model: TU921S
• Full Part Number: 3KDE175111L9210
• Product Type: Redundant Termination Unit
• System: ABB Advant S900 I/O
• Supported I/O Capacity: Up to 16 I/O modules
• Spare Model: 3KDE175111L9210

Hardware Specifications

Industrial Control and I/O Architecture

The TU921S is designed for ABB Advant S900 I/O installations where redundant power and communication paths are required. Its termination architecture supports connection of up to 16 I/O modules and allows configuration changes while the system remains in operation.

• Redundant power and communication paths support system-level availability requirements.
• Hot configuration in run permits configuration activities without a complete system shutdown.
• Hot swap functionality supports module replacement procedures where the overall system architecture permits live maintenance.
• FDT/DTM integration provides a standardized method for configuration and diagnostic access.
• Extended diagnostics and auto-diagnostics assist with identification of termination and communication-related conditions.
• G3 coating is specified for all components.
• ATEX certification supports installation requirements for Zone 1 environments when the complete installation complies with the applicable certification and system conditions.
• The termination unit provides the physical interface for up to 16 I/O modules.

Ordering Information

• 1 x ABB TU921S Redundant Termination Unit
• Part Number: 3KDE175111L9210
• Spare Model: 3KDE175111L9210
• I/O modules are not included unless separately specified.
• Additional mounting or system accessories are not identified in the supplied product data.

Field Installation Guidelines

Mounting and Mechanical Installation

• Install the termination unit according to the Advant S900 system installation documentation.
• Verify mechanical alignment before connecting I/O modules or field wiring.
• Ensure the mounting structure supports the 2.96 kg unit and connected wiring.
• Maintain adequate clearance for module removal and hot-swap maintenance procedures.

Wiring and Signal Routing

• Route power, communication, and field signal wiring according to the system installation requirements.
• Keep communication wiring separated from high-energy power conductors where practical.
• Use appropriate cable shielding and connect shields according to the plant grounding concept.
• Avoid excessive cable bending or mechanical stress at termination points.
• Confirm all terminal assignments before energizing the system.

Redundant Configuration

• Verify both redundant power and communication paths before placing the system into service.
• Check diagnostic indications after installation and following any module replacement.
• Confirm that redundancy is maintained after wiring modifications or hot-swap procedures.
• Perform functional checks using the applicable Advant S900 engineering and diagnostic tools.

Frequently Asked Questions

• Can the TU921S support redundant power?

  Yes. The supplied data specifies power redundancy as a supported function. The complete system configuration must provide the corresponding redundant power architecture.

• Does the TU921S support redundant communication?

  Yes. Communication redundancy is specified for the TU921S. The actual redundancy behavior depends on the connected S900 I/O system configuration.

• How many I/O modules can the TU921S terminate?

  The TU921S is specified as a termination unit for up to 16 I/O modules. The supported module combinations must follow the applicable S900 system configuration rules.

• Can the TU921S be configured while running?

  Yes. The product information specifies hot configuration in run, allowing supported configuration activities without stopping normal system operation.

• Does the TU921S support hot swapping?

  Yes. Hot swap functionality is specified. Live replacement must follow the applicable S900 installation and maintenance procedures.

• What diagnostic functions are available?

  The unit provides extended diagnostics and auto-diagnostics. FDT/DTM support is also specified for configuration and diagnostic access.

• Is the TU921S suitable for Zone 1 installation?

  The supplied data specifies ATEX certification for installation in Zone 1. Certification conditions must be verified against the complete installation before use.

• What environmental coating is specified?

  G3 coating is specified for all components. This coating designation should be considered together with the actual installation environment and applicable system documentation.