Product Overview

The TU838 (3BSE008572R1) Termination Units, also cataloged as the TU838 Termination Units, operates as a dedicated hardware component for signal processing or control execution within industrial automation architectures. Designed specifically for the S800 I/O system, this Extended Module Termination Unit (MTU) serves as the primary electrical interface between field-level wiring and I/O modules. It facilitates signal distribution, field power management, and ModuleBus communication. The unit is optimized for dense cabinet layouts, supporting cascading configurations to enable efficient system expansion within Advant OCS and System 800xA control environments.

Technical Specifications

Brand-Specific Technical Block

The TU838 utilizes the S800 I/O backplane architecture to ensure deterministic communication via the ModuleBus. As a node in the S800 system, the unit bridges the field-wiring layer to the I/O module layer, allowing for the cascading of additional MTUs through a daisy-chain bus configuration. The design includes 3-wire field interfaces and two isolated process voltage groups, subject to the compatibility of the mounted I/O module. Mechanical keying with 36 unique positions ensures that only the intended I/O module type can be mated to the unit, preventing hardware damage during installation. The unit provides a continuous ground path through the DIN rail latching mechanism, facilitating electromagnetic compatibility (EMC) compliance.

Ordering Information

• Included items: TU838 Extended Module Termination Unit, mounting latch hardware.

• Standard package: Industrial anti-static sealed packaging.

• Optional accessories: I/O module field terminal covers, cable marking accessories, DIN rail ground connectors.

Installation Guidelines

• Ensure the DIN rail is securely mounted and clean to allow for proper functional earth (ground) contact through the latching mechanism.

• Use 3-wire field connections as specified; ensure all terminations are tightened to the recommended torque to avoid signal degradation.

• Maintain proper spatial separation between TU838 units and high-voltage power components to mitigate electromagnetic interference.

• Check mechanical keying alignment before inserting the I/O module to prevent mechanical stress on the MTU backplane pins.

• If cascading, ensure the ModuleBus cable is fully seated and locked to maintain continuous data flow between termination units.

• Verify field power voltage levels at the terminal inputs before mounting the active I/O module.

Frequently Asked Questions

Q: Does the TU838 support hot-swap behavior?

A: The MTU acts as a passive base; hot-swapping is permitted for the active I/O module mounted upon it, provided system configuration supports this.

Q: How does the unit affect backplane load?

A: The TU838 is a passive electrical interface and does not draw power from the bus; it merely facilitates the distribution of power and signals.

Q: Is there a redundancy switching delay?

A: The MTU is a passive physical component; redundancy timing is entirely dependent on the host controller and I/O module configuration.

Q: Is firmware compatibility required?

A: As a physical termination unit, the TU838 does not contain firmware; however, the mounted I/O module must be compatible with the system software.

Q: Does the unit provide signal isolation?

A: Signal isolation is dependent on the I/O module installed on the TU838; the MTU itself supports the physical isolation paths defined by the module.

Q: What are the field wiring constraints?

A: Field wiring must not exceed the current rating of 3 A per channel; ensure wire gauge is appropriate for the applied load and distance.

Q: Can the TU838 be mounted horizontally and vertically?

A: Yes, the unit is designed for both horizontal and vertical mounting on standard DIN rails, provided ambient cooling requirements are met.

Q: How is the unit grounded?

A: Grounding is established automatically through the high-integrity metallic latching mechanism connected directly to the DIN rail.