The ABB CI865K01 with part number 3BSE040795R1 is a rack-mounted dedicated bus communication module for ABB AC 800M controllers under System 800xA DCS, specially designed for bridging legacy Satt ControlNet and Satt distributed I/O systems. Unlike CI862K01 for TRIO/Genius protocols, it adopts a single BNC coaxial connector for Satt I/O bus wiring, and cannot serve as a universal ControlNet interface or match high-integrity AC 800M safety controllers. It draws 24V DC power from the AC800M CEX backplane bus with a typical operating current of 120mA and rated power consumption of 2.88W, featuring built-in transient surge suppression and reverse polarity protection to adapt to unstable industrial cabinet power supply. It provides 500V DC galvanic isolation between the CEX backplane and field Satt I/O bus, preventing ground loop potential difference interference across dispersed field cabinets and avoiding accidental bus offline. The module supports scanning for up to 31 independent Satt rack I/O and Series 200 distributed I/O stations, realizing seamless data synchronization between outdated Satt I/O assets and modern AC800M control logic. It follows unified AC800M hardware standards: dimensions 185mm × 59mm × 127.5mm, net weight 0.7kg, occupying two standard rack slots, with a maximum of 4 such modules deployed on one single CEX bus. Three front-panel LED indicators separately display backplane power status, CEX bus communication and Satt field bus activity for on-site fault diagnosis without Control Builder M configuration software. It meets ISA 71.04 G3 corrosion protection grade and IEC 61000-6-2 EMC standards, with operating temperature from 5°C to 55°C, storage temperature from -40°C to 70°C, and 5%-95% non-condensing humidity tolerance under IP20 enclosure. It supports hot swapping when CPU load is below 40% with zero pre-configuration required before replacement. Manufactured in Sweden with CE, RoHS and WEEE certifications, it is primarily used for low-cost legacy Satt I/O system renovation in pulp, chemical and municipal water treatment plants.