ABB TB842
ABB TB842
ABB TB842
ABB TB842

ABB TB842 | Symphony Harmony Remote I/O Communication Coupler

  • Brand: ABB
  • Model: TB842
  • Product Type: Remote I/O Communication Coupler
  • Series: Symphony Harmony
  • Core Function: Connects remote I/O stations to Symphony Harmony DCS controllers via Profibus DP, managing cyclic data exchange and acyclic diagnostics.
  • Key Specs: Profibus DP (up to 12 Mbps), supports up to 32 I/O modules per segment, 1500VAC isolation.
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Part number: ABB TB842
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Description

TB842: Product Overview
The TB842 is a remote I/O communication coupler designed for integration into ABB Symphony Harmony distributed control systems (DCS). Its role is to act as a fieldbus gateway, linking geographically dispersed I/O stations—equipped with digital/analog modules—to the central Symphony Harmony controller (e.g., AC800M). In continuous process industries, where running individual cables from field devices to a central rack is impractical, this module reduces wiring complexity by enabling daisy-chained remote stations.
Functionally, the TB842 processes cyclic data (real-time I/O updates) and acyclic messages (diagnostic/config commands) via Profibus DP (up to 12 Mbps). It aggregates input signals from remote devices (e.g., sensors, switches) and transmits them to the controller, while forwarding output commands (e.g., valve positions, motor starts) to actuators. As part of the Symphony Harmony family, it leverages the platform’s modular architecture, hot-swappable components, and compatibility with ABB Control Builder M engineering software. Benefits include simplified system expansion, reduced installation labor, and unified configuration workflows that streamline commissioning.ABB TB842
TB842: Technical Specifications
  • Model Number: TB842
  • Manufacturer: ABB
  • Product Type: Remote I/O Communication Coupler
  • Protocol Support: Profibus DP (up to 12 Mbps, master/slave mode, V1-compliant)
  • I/O Capacity: Up to 32 I/O modules per segment (e.g., S800 I/O)
  • Data Rate: 9.6 kbps to 12 Mbps (configurable)
  • Operating Temperature: -25°C to +60°C
  • Isolation Voltage: 1500VAC (channel-to-bus, channel-to-channel)
  • Power Supply: 24V DC (from Symphony Harmony rack backplane, 18-32V DC range)
  • Power Consumption: 3W (typical, all segments active)
  • Dimensions: 245mm x 135mm x 115mm (width x height x depth, fits Symphony I/O rack)
  • Weight: 0.8kg
  • Certifications: CE, UL, cULus, RoHS

    ABB TB842

    ABB TB842

Core Features & Customer Value​
The TB842 is engineered to address challenges in distributed I/O integration. Its support for up to 32 I/O modules per segment minimizes the number of couplers needed in large facilities—for a refinery with 100 remote sensors, this reduces coupler count from 4 to 3, cutting wiring and mounting costs. The 1500VAC isolation protects the DCS from ground loops and EMI, critical in environments with VFDs or high-power motors, ensuring signal integrity for safety systems like emergency shutdown.
Hot-swap capability allows replacement without de-energizing the rack, minimizing downtime during maintenance—a key advantage in continuous processes like chemical manufacturing. Built-in diagnostics (LED indicators for power, communication, and segment status) and integration with Control Builder M enable engineers to monitor link health, identify faulty modules, and troubleshoot faults remotely, reducing mean time to repair (MTTR) by 30-40%.
The module’s compatibility with Symphony Harmony’s modular I/O family (e.g., S800) allows reuse of existing I/O configurations across projects, streamlining retrofits. For procurement, this standardization lowers spare parts inventory complexity.
Typical Applications​
The TB842 is deployed in Symphony Harmony DCS environments requiring remote I/O connectivity. In a petroleum refinery’s crude distillation unit, it links an AC800M controller to 24 S800 I/O modules (monitoring 500+ temperature/pressure signals) via Profibus DP, eliminating 1,000+ feet of individual sensor cabling. The 12 Mbps data rate ensures real-time updates for reflux ratio adjustments.
At a chemical plant’s polymerization reactor, the coupler connects remote I/O stations (with agitator overload switches and valve position sensors) to the DCS. Its -25°C cold-start capability supports winter startups, and hot-swap functionality allows maintenance during planned turnarounds without halting reactions.
In a municipal wastewater treatment facility, the TB842 interfaces the central DCS with 8 remote pump station I/O racks (monitoring pump status, flow meters). Data is transmitted for remote adjustment of chemical dosing, with the module’s compact size (245x135x115mm) fitting into space-constrained control panels.

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