What Is the ABB TU846?
When redundant field communication and I/O are critical for uptime, the ABB TU846 (3BSE022460R1) provides a robust solution. This module termination unit (MTU) supports redundant configuration of the CI840/CI840A field communication interface and redundant I/O modules. Designed as a passive unit, it connects power supply, two electrical ModuleBuses, two CI840/CI840A modules, and two rotary switches for station address settings (0 to 99). Mechanical keying with 36 combinations prevents incorrect module insertion, ensuring system integrity.
Technical Specifications Breakdown
- Power Input: 24 V d.c. (19.2 - 30 V) ensures stable operation in industrial environments.
- Communication Protocol: PROFIBUS DP-V1 with DSUB9 connectors for reliable data exchange.
- ModuleBus Current Distribution: Maximum 5 V at 1.5 A and 24 V at 1.5 A supports peripheral modules.
- Mechanical Keying: 36 different combinations via four keys (six positions each) prevent wrong module installation.
- Environmental Ratings: Operating temperature 0 to +55 °C (approvals at +5 to +55 °C), storage -40 to +70 °C, and IP20 protection.
- Dimensions: Width 124 mm (4.88"), height 186 mm (7.32") including latch, depth 47 mm (1.85"), weight 0.5 kg (1.1 lbs).
Industry Applications
In process control systems requiring high availability, the TU846 enables redundant I/O configurations that minimize downtime. For example, in oil and gas plants, the MTU supports dual CI840/CI840A modules to maintain communication even if one path fails. Similarly, in power generation, the redundant setup ensures continuous data acquisition from critical sensors. The PROFIBUS DP-V1 protocol integrates seamlessly with existing automation networks.
Installation & Setup Guidance
Mount the TU846 vertically or horizontally on a DIN rail using its latching device for locking and grounding. Connect the power supply (24 V d.c.) and two ModuleBuses via the dedicated connectors. Set the station address using the two rotary switches (0 to 99). Use mechanical keys to configure the MTU for the correct module types—each key has six positions, offering 36 combinations. Acceptable wire sizes range from 0.25 to 2.5 mm² (24-14 AWG) with recommended torque 0.5-0.6 Nm and stripping length 6-7.5 mm (0.24-0.30 in). Ensure the maximum ModuleBus length from the TU846 to the terminator is 2.5 meters. Note that the unit cannot be replaced with power applied and needs space to the left for removal.
Maintenance & Reliability
The passive design of the TU846 requires minimal maintenance. Periodically inspect connections for tightness and verify that the DIN rail latch remains secure. Operating within the specified temperature range (0 to +55 °C) and relative humidity (5 to 95%, non-condensing) ensures long-term reliability. The CE marking and compliance with EN 61010-1, UL 61010-1, and hazardous location certifications (cULus Class 1 Zone 2, ATEX Zone 2) confirm its suitability for demanding environments. For vertical mounting, limit ambient temperature to 40 °C (104 °F).
Compatibility & Integration
The TU846 works with redundant I/O modules and the CI840/CI840A field communication interface. It supports PROFIBUS DP-V1 protocol via DSUB9 connectors and service ports via RJ45 connectors. For optical ModuleBus connections, use the TB842 module connected via TB846. The MTU integrates with ABB's automation systems and is part of the TU846/TU847 family—TU847 is for single I/O modules. Line redundancy and module redundancy are built-in, but hot swap is not supported.
Selection Guide & Purchasing Advice
Before purchasing the ABB TU846, verify that your system requires redundant CI840/CI840A and I/O configuration. Confirm the power supply voltage (24 V d.c.) and that the maximum ModuleBus length (2.5 meters) meets your layout. Check compatibility with existing PROFIBUS DP-V1 networks. SpareTechPLC offers the ABB TU846 (3BSE022460R1) as a reliable supplier for industrial automation parts. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Frequently Asked Questions
Q1: Can the ABB TU846 be used with single I/O modules?
No, the TU846 is designed for redundant I/O modules. For single I/O modules, use the TU847.
Q2: What is the maximum ModuleBus length supported by the TU846?
The maximum ModuleBus length from the TU846 to the ModuleBus terminator is 2.5 meters.
Q3: How do I set the station address on the TU846?
Use the two rotary switches on the MTU to set the station address from 0 to 99.
Q4: What communication protocol does the TU846 support?
The TU846 supports PROFIBUS DP-V1 via DSUB9 connectors.
Q5: Is the TU846 hot-swappable?
No, the TU846 cannot be replaced with power applied. Power down before removal.
