Product Overview

The Allen-Bradley 1797-BIC​ is a FLEX® Ex Bus Isolator and Intrinsic Safety (IS) barrier module manufactured by Rockwell Automation for use in the 1797 FLEX Ex distributed I/O system. Positioned between a standard non-intrinsically-safe FLEX I/O™ adapter (such as a 1794-AENTR or 1794-ACNR15) located in the safe area (Zone 2 / Division 2 or control room) and one or more 1797-series intrinsically safe input/output modules mounted in the hazardous area (Zone 0, 1 / Division 1), the Allen-Bradley 1797-BIC​ provides galvanic isolation and strict energy limitation on both the communication bus signals and the 5 VDC / 24 VDC power fed to the Ex-side I/O modules. This ensures that no more than the permissible ignition energy—defined by its certified intrinsic safety parameters (Uo, Io, Po)—can reach the hazardous-area wiring and connected field devices, keeping the installation compliant with ATEX, IECEx, FM, and cCSAus hazardous-location standards.The Allen-Bradley 1797-BIC​ draws its operating power from a 24 VDC supply in the safe area (18–32 VDC input range) and internally generates the isolated, intrinsically safe 5 VDC logic and limited 24 VDC field power required by up to eight 1797 Ex I/O modules on its downstream bus. Communication with the FLEX I/O adapter is transparent—no special configuration, software drivers, or addressing is required; the Allen-Bradley 1797-BIC​ simply passes the FlexBus™ protocol bidirectionally while enforcing the safety energy barrier. A green PWR LED on the front indicates that the isolator is correctly energized and the IS output is active; loss of this LED signals either missing supply voltage or an internal fault condition.Designed for DIN-rail mounting directly adjacent to the FLEX I/O adapter or at the zone boundary inside a certified enclosure arrangement, the Allen-Bradley 1797-BIC​ enables process and hybrid-industry users to deploy certified intrinsically safe I/O close to field instruments—temperature transmitters, solenoid valves with IS barriers, proximity switches—while keeping the control network and controller in the safe area. Its compact form factor and transparent operation make the Allen-Bradley 1797-BIC​ the foundational building block of any compliant FLEX Ex I/O installation.

Technical Specifications

Main Features and Advantages

Certified intrinsic safety energy limitation:The primary function of the Allen-Bradley 1797-BIC​ is to act as a certified Zener/galvanic barrier that limits voltage, current, and power delivered to the hazardous-area side to levels below the ignition energy of explosive gas/ dust atmospheres. With certified parameters Uo ≤ 5.75 V, Io ≤ 400 mA, Po ≤ 2.05 W, the Allen-Bradley 1797-BIC​ satisfies the entity concept for connecting Ex ia / Ex ib certified field-linked 1797 I/O modules and associated field instruments in Zone 0/1 or Division 1 locations.Transparent FlexBus pass-through—no programming required:The Allen-Bradley 1797-BIC​ does not introduce a new node address, IP, or DeviceNet MAC ID. It is completely transparent to the control system: the FLEX I/O adapter sees the 1797 Ex modules exactly as it would see standard 1794 modules. RSLinx® / Studio 5000® Auto-Discover the downstream I/O, and all data mapping, RPIs, and fault handling behave identically to a non-IS FLEX I/O rack. This eliminates a common source of configuration error and shortens commissioning time in hazardous-area projects.Single module powers up to eight Ex I/O modules:One Allen-Bradley 1797-BIC​ can supply isolated, intrinsically safe logic power and bus communication to a local cluster of up to eight 1797-series input, output, analog, or specialty modules. This keeps the Ex-side I/O density high while minimizing the number of IS barriers and separate power feeds required in the safe area—an important cost and panel-space consideration in skid-mounted process packages and multi-loop analytical enclosures.Mixed standard and Ex I/O on the same adapter (with separate BIC):While the Allen-Bradley 1797-BIC​ itself isolates the Ex-side modules, standard 1794 FLEX I/O modules can be mounted on the same FLEX I/O adapter (on the safe-side bus) without an isolator—allowing a hybrid rack architecture where non-hazardous-area points are handled by standard modules and hazardous-area points by 1797 modules behind a Allen-Bradley 1797-BIC. This flexibility is unique to the FLEX Ex architecture versus wholly separate IS remote I/O families.Clear status indication for troubleshooting:The front-panel green PWR LED on the Allen-Bradley 1797-BIC​ confirms that the 24 VDC supply is present and the IS output is active. If the LED is off, the technician immediately knows to check the safe-area 24 VDC supply or the module’s seating on the DIN rail/bus. Because the isolator is passive in the data path, communication faults are reported by the FLEX I/O adapter’s normal I/O timeout mechanisms, simplifying root-cause analysis.