The ABB CI856K01, with order number 3BSE026055R1, is a high-performance S100 I O communication interface module designed for the ABB AC800M controller family within the System 800xA distributed control system architecture. This module serves as the essential link between the AC800M main controller and legacy S100 remote I O racks. It is specifically engineered for industrial control system upgrades and expansions, allowing users to retain existing S100 I O hardware, field wiring, and terminal blocks while modernizing the control platform. The module communicates with the controller via the CEX bus, requiring no external power supply and incorporating an independent communication processing unit to avoid consuming main CPU resources.
The CI856K01 supports connection to up to five S100 I O racks, with each rack capable of housing up to 20 I O boards, providing substantial expansion capacity for large scale industrial applications. The module fully supports hot swap functionality, enabling online replacement without system downtime, and offers HART routing capabilities for direct collection of HART data from smart field instruments without requiring additional gateways. The device operates within a wide temperature range of -25 to +70 degrees Celsius, making it suitable for demanding environments such as power generation, metallurgical processing, and chemical manufacturing.
Manufacturer: ABB
Part Number: CI856K01 (3BSE026055R1)
Product Type: S100 I O Communication Interface Module
Compatible Systems: AC800M, System 800xA DCS
Bus Interface: CEX bus
Maximum I O Racks: 5 S100 I O racks
Maximum I O Boards per Rack: 20
Power Supply: CEX bus powered, 24 V DC (19.2 to 31.2 V DC)
Operating Temperature: -25 to +70 degrees Celsius
Protection Rating: IP20
Mounting: CEX bus rack with TP856 base
Supported Features: Hot swap, HART routing, hot configuration
Dimensions: 127.5 x 59 x 186 mm
Weight: 0.7 kg

The CI856K01 enables seamless communication between the AC800M controller and distributed S100 I O devices using the ABB proprietary S100 I O protocol. The module is installed on a TP856 base, which provides physical support and bus connections. It manages the master slave relationship between the controller and remote I O racks, cyclically exchanging process data and diagnostic information. The HART routing feature allows the module to extract HART digital data superimposed on the 4 to 20 mA analog signals from intelligent instruments, making this data available to the control system for asset management and predictive maintenance.
The CI856K01 is installed into a CEX bus rack alongside AC800M CPU modules and other communication interfaces. Configuration is performed using ABB Control Builder M software, which provides a graphical interface for defining I O mappings, setting communication parameters, and configuring HART channels. The hot configuration feature allows engineers to modify I O configurations online while the system remains in operation, minimizing production disruption. The module occupies a single slot in the CEX bus rack and connects to S100 I O racks via TK575 or TK580 bus extension cables through the TP856 base.
This communication interface is widely deployed in process industries requiring migration from older ABB control systems to the modern AC800M platform while preserving investment in existing S100 I O infrastructure. Typical applications include power plant boiler control systems, chemical reactor monitoring and control, metal processing mills, and water treatment facilities. The CI856K01 is particularly valuable in brownfield projects where minimal downtime is critical and rewiring of field devices is impractical. For system integrators and maintenance engineers, this module provides a reliable bridge between modern DCS architectures and legacy field I O, extending the service life of existing field equipment.



