Configured for field-level wiring termination in S800 I/O distributed control network platforms, the ABB TU844 (3BSE021445R1 Module Termination Unit) provides direct physical signal distribution and mechanical mounting support for I/O modules.

Nomenclature and Part Identification

• Base Model: TU844
• Ordering Part Number: 3BSE021445R1
• Function: Termination and Field Connectivity
• Series: S800 I/O

Mechanical and Environmental Specifications

I/O Density Scaling and Backplane Connectivity

The TU844 functions as a passive interface carrier, facilitating the routing of field signals to the corresponding S800 I/O module via the MTU-to-module connector. The design supports high-density I/O configurations, ensuring low-resistance electrical pathways for critical process signals. By utilizing standardized S800 backplane architecture, this unit permits deterministic I/O density scaling and physical signal isolation, maintaining system integrity across modular control nodes.

Ordering Info

• 1 unit: TU844 Module Termination Unit
• 1 set: Integrated marking labels and mounting hardware
• 1 unit: Technical installation sheet

Mechanical Mounting and Wiring Procedures

• Installation Guidelines:
  • Align the termination unit with the 35 mm DIN rail and press until the mechanical latch engages firmly.
  • Use a flat-head screwdriver to release the locking mechanism for unit removal.
• Cabling Standards:
  • Strip field wires to the specified length to ensure full contact within the spring or screw-type terminals.
  • Torque terminal screws to the recommended Nm rating to prevent loosening due to thermal expansion or vibration.
  • Employ cable management ducts to strain-relieve field conductors and ensure orderly routing to the unit.

Frequently Asked Questions

• Q: Is the TU844 electrically active?

  A: No, the TU844 is a passive termination unit; it provides the physical connection for field wiring to the I/O module and contains no active electronic components.

• Q: Can this unit be used for redundant I/O?

  A: Redundancy compatibility depends on the specific S800 I/O module paired with this unit. Verify the compatibility matrix for the intended module type.

• Q: What is the maximum wire gauge supported?

  A: The terminal blocks are designed to accommodate standard industrial signal wire sizes, typically up to 2.5 mm squared (approx. 14 AWG).

• Q: Does the unit provide surge protection?

  A: The TU844 acts as a bridge; surge protection must be provided by external devices or the associated I/O modules if required by the application.

• Q: Is this unit compatible with all S800 I/O modules?

  A: No, it is designed for specific I/O module pin-out configurations. Check the compatibility table between the TU unit and the I/O module.

• Q: How is grounding handled?

  A: Shielded cables should be terminated to the common ground rail or the dedicated shield connection points provided on the termination unit.

• Q: Is the unit resistant to high-vibration environments?

  A: The unit is designed for standard industrial cabinet environments. In high-vibration scenarios, ensure the DIN rail is securely fastened to the backplate.

• Q: Can I replace the terminal blocks individually?

  A: The terminal interface is integrated into the TU844 design; the entire unit is replaced as a single hardware assembly.