Description
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | ABB |
| ABB Type Designation | TB840A |
| Article Number | 3BSE037760R1 |
| Product Type | ModuleBus Cluster Modem |
| System | ABB S800 I/O |
| Communication Protocol | ModuleBus |
| Role | Slave |
| Optical Interfaces | 2 fiber-optic ports |
| Electrical Interface | ModuleBus to connected S800 I/O modules |
| Line Redundancy | Yes |
| Module Redundancy | Yes |
| Hot Swap | Yes |
| Typical 24 VDC Consumption | 120 mA |
| Operating Temperature | 0 to +55 °C |
| Storage Temperature | -40 to +70 °C |
| Relative Humidity | 5–95%, non-condensing |
| Corrosion Protection | ISA-S71.04 G3 |
| Protection Class | IP20 |
| Dimensions | 54 × 119 × 96 mm |
| Weight | Approx. 0.2 kg |
| Hazardous Location | Class I Div. 2 / Class I Zone 2 cULus; ATEX Zone 2 |
| Marine Certifications | ABS, BV, DNV-GL, LR |
The 24 V consumption, dimensions, environmental ratings, redundancy functions, and certification data are documented by ABB.
TB840A-3BSE037760R1
Application Scenarios & Pain Points
A common S800 expansion problem is simple: the local electrical ModuleBus has reached its practical module limit, but the plant still needs I/O farther away. Running long electrical connections through a large cabinet or process area is rarely the cleanest answer. TB840A provides the optical distribution point.
Typical Applications
- ABB 800xA Distributed I/O: TB840A connects S800 I/O clusters through the optical ModuleBus architecture, allowing I/O to be distributed away from the primary electrical ModuleBus section.
- Redundant I/O Stations: Designed for 1+1 redundant operation, with each TB840A connected to a different optical ModuleBus line while sharing the same electrical ModuleBus.
- Large Process Plants: Useful where I/O cabinets are separated geographically and fiber provides a practical interconnection path.
- Legacy 800xA Maintenance: A particularly important spare when an installed S800 architecture already uses TB840A rather than a newer Ethernet-based I/O arrangement.
Field Case:
A process plant adding a remote I/O cabinet may discover that the existing electrical ModuleBus arrangement cannot simply be extended to the required location. A TB840A pair can provide the optical distribution path while preserving the redundant architecture—provided the optical cabling and compatible MTU arrangement are correctly selected.
Related Products
- ABB TB840 3BSE021456R1 — Earlier TB840 ModuleBus cluster modem family member. is the later designation used for redundant optical ModuleBus applications; confirm the installed system revision before treating them as direct replacements.
- ABB TB820V2 3BSE013208R1 — Optical ModuleBus cluster modem intended for non-redundant operation. ABB identifies TB820V2 as a non-redundant optical cluster modem, making it a functional alternative only where redundancy is not required.
- ABB TB825 3BSE036634R1 — Multimode optical ModuleBus interface. It provides optical connectivity but does not provide the same 1+1 module/line redundancy architecture as .
- ABB TB826 3BSE061637R1 — Single-mode optical ModuleBus interface. Appropriate where the fiber infrastructure requires single-mode transmission; its architecture differs from .
- ABB TB842 3BSE022464R1 — ModuleBus optical port hardware for S800 I/O. It is a related optical interface, but the redundancy and system architecture differ from .
- ABB TU840 3BSE021456R1 — Redundant Module Termination Unit for TB840/, supporting redundant I/O with a single power arrangement. ABB specifies 24 VDC input and dual ModuleBus connections.
- ABB TU848 3BSE042558R1 — Redundant MTU for TB840/ with dual power. This is the better match where power redundancy is part of the I/O station design.
- ABB TU849 3BSE042560R1 — Redundant TB840/ MTU for a single I/O / dual-power arrangement. The application differs from TU840 and TU848, so cabinet configuration must be checked.
- ABB TB807 3BSE008538R1 — ModuleBus terminator used in applicable ModuleBus configurations. It is supporting termination hardware, not a replacement for .
