Product Overview
When designing distributed process I/O systems, maintaining reliable communication between clusters is critical. The ABB TB840A Modulebus Cluster Modem addresses this need by providing a fiber optic interface for the Optical ModuleBus in S800 I/O architectures. As part of ABB's comprehensive S800 I/O family, the TB840A enables redundant configurations where each modem connects to different optical ModuleBus lines while sharing the same electrical ModuleBus. This design ensures continuous operation even if one fiber path fails.
Technical Specifications Breakdown
Key parameters from the TB840A datasheet define its capabilities:
- Power Consumption: 24 V consumption typ. 120 mA – low power draw minimizes load on system power supplies.
- Operating Temperature: 0 to +55 °C (+32 to +131 °F), with approvals issued for +5 to +55 °C – suitable for most industrial environments.
- Storage Temperature: -40 to +70 °C (-40 to +158 °F) – allows safe storage in harsh conditions.
- Protection Class: IP20 according to EN60529, IEC 529 – requires installation in a clean, dry enclosure.
- Dimensions: Width 54 mm (2.13 in.), Height 119 mm (4.69 in.), Depth 96 mm (3.78 in.) – compact footprint fits standard cabinets.
- Weight: 0.2 kg (0.44 lbs) – lightweight for easy handling.
Industry Applications
The TB840A excels in process industries requiring high availability, such as oil and gas, chemical, and power generation. In a typical refinery, multiple I/O clusters distributed across a plant communicate via fiber optic links. The TB840A ensures each cluster remains connected to the controller even if one fiber line is damaged, reducing unplanned downtime. For manufacturing lines with more than 12 I/O modules per station, the TB840A allows expansion by connecting up to seven clusters on the fiber optic ModuleBus.
Installation & Setup Guidance
Mount the TB840A on a DIN rail within an IP20-rated cabinet. Connect the electrical ModuleBus to the I/O modules using the TU840 or TU841 termination unit (MTU). For redundant configurations, use two TB840A modems with the TU840 MTU to connect each to a separate optical ModuleBus line. Ensure input power is fused as per the datasheet. The modem acts as a slave on the ModuleBus, so no configuration of communication parameters is needed beyond standard system setup.
Maintenance & Reliability
Regularly inspect fiber optic connections for dust or damage. Verify that the operating temperature stays within 0 to +55 °C, especially in vertically mounted cabinets where the max ambient temperature drops to 40 °C. The TB840A includes supervisory functions for the I/O ModuleBus and power supply, which can be monitored via the controller. Periodic checks of the 24 V supply current (typ. 120 mA) help detect early signs of power issues.
Compatibility & Integration
The TB840A communicates via the ModuleBus protocol and operates as a slave device. It is designed for use with HI Controller systems and supports hot swap, line redundancy, and module redundancy. Up to 12 I/O modules can connect to the electrical ModuleBus, and up to seven clusters can be linked via fiber optic. The modem works with TU840 (for redundant dual ModuleBus) and TU841 (for single ModuleBus) MTUs.
Selection Guide & Purchasing Advice
Before ordering the TB840A, verify your system requires fiber optic redundancy. If a single optical path suffices, consider the TB840. For redundant setups, the TB840A is essential. Ensure your cabinet provides IP20 protection and adequate ventilation. SpareTechPLC stocks the TB840A (3BSE037760R1) and compatible TU840/TU841 MTUs. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Frequently Asked Questions
Q: What is the difference between TB840 and TB840A?
A: The TB840A is used in redundancy configurations where each modem connects to different optical ModuleBus lines but shares the same electrical ModuleBus. The TB840 typically supports non-redundant setups.
Q: How many I/O modules can I connect to one TB840A?
A: A maximum of 12 I/O modules can be connected to the electrical ModuleBus, and up to seven clusters can be connected via the fiber optic ModuleBus.
Q: Does the TB840A require external power?
A: Yes, it consumes 24 V typ. 120 mA. The input power must be fused as per the datasheet.
Q: What certifications does the TB840A hold?
A: It carries CE marking, electrical safety per EN 61010-1 and UL 61010-1, hazardous location approvals (C1 Div 2 cULus, C1 Zone 2 cULus, ATEX Zone 2), and marine certificates (ABS, BV, DNV-GL, LR).
Q: Can I use the TB840A with a non-ABB controller?
A: The TB840A is designed for ABB's S800 I/O system and communicates via ModuleBus. It is intended for use with ABB controllers supporting this protocol.
