ABB TU860 S800 I/O Module Termination Unit

Configured for signal distribution and redundant ModuleBus execution in S800 I/O platforms, the ABB TU860 (TU860 3BSE078710R1 Module Termination Unit) provides direct physical/electrical execution.

Hardware Specifications

Backplane Bus Communication Velocity and Redundant Network Execution

The TU860 forms the physical interface layer for S800 high-availability configurations, connecting field signals while accommodating Ethernet fieldbus communication adapters such as the CI845, TC810, and TC811. The unit hosts up to 12 single or redundant S800 I/O modules and MTUs, distributing deterministically routed signals across the internal ModuleBus architecture directly to AC 800M process controllers. Integrated dual 6-position mechanical keying mechanisms physically enforce module matching, preventing insertion errors during system assembly or field maintenance.

Field Installation Guidelines

Mount the unit on standard DIN rails in either horizontal or vertical orientation inside a protected enclosure meeting IP54 or higher standards. Secure field conductors to the terminal blocks using a torque specification between 0.5 Nm and 0.6 Nm after stripping insulation to exactly 7 mm. Observe thermal derating limits: horizontal mount configurations operate up to 55 deg C, whereas vertical mount orientations restrict maximum operating ambient temperatures to 40 deg C due to reduced convective cooling dynamics. Ensure complete grounding of the DIN rail structure to maintain the full 2000 VAC dielectric isolation limit across all field channels.

Frequently Asked Questions

Q: Does the TU860 support hot-swapping of mounted redundant modules during live operation?

A: Yes, compatible high-integrity I/O modules (DI880, DO880, AI880, AO880) can be replaced on the active MTU base without interrupting backplane network communication or field wiring on adjacent units.

Q: What restricts the maximum operating temperature to 40 deg C in vertical mounting arrangements?

A: Vertical orientation alters internal convective heat dissipation pathways, causing localized thermal buildup that necessitates a reduced maximum ambient operating threshold to preserve component life.

Q: How does mechanical keying prevent mismatched module placement?

A: Two six-position mechanical keying dials set to a specific alphanumeric code align with matching physical notches on compatible modules, blocking physical insertion of non-designated module types.