ABB CI855K01 (3BSE018106R1) – Redundant Controller for Industrial Automation Systems

If you’re upgrading or maintaining an ABB AC 800M control system, the CI855K01 is one of those components that tends to fly under the radar—until it doesn’t work. From my experience, this dual-port redundant controller module is typically used in environments where uptime matters more than cost savings. It’s not flashy, but it’s solid. One thing I appreciate is how seamlessly it integrates into existing Modbus and Profibus DP networks without requiring a full system overhaul.

Key Features

• Dual-channel redundancy – Ensures continuous operation even if one communication path fails. In many cases, this avoids unplanned shutdowns in power plants or water treatment facilities.
• Supports both Profibus DP and Modbus protocols – Offers flexibility when interfacing with legacy drives or third-party I/O systems. You might notice that this becomes especially useful during phased modernization projects.
• Hot-swappable design – Can be replaced without powering down the rack, which reduces maintenance downtime significantly.
• Integrated diagnostics – LED indicators provide real-time status feedback, making troubleshooting faster compared to older models without on-board reporting.
• Designed for AC 800M controllers – Specifically built to work within ABB’s Symphony Plus ecosystem, so compatibility with other modules like CI854 or CP850 is generally seamless.

Technical Specifications

Application Fields

This module shows up most often in process industries—think oil refineries, chemical plants, and district heating systems—where Profibus DP networks are still the backbone of field communication. It also appears in retrofitted wastewater plants that need reliable master-to-slave communication with remote pump stations. In my view, its strongest use case is in safety-critical applications where losing communication with field devices isn’t an option. The redundancy feature pays off here, even if it adds a bit more complexity during initial setup.

Advantages & Value

Procurement teams tend to focus on long-term supportability, and that’s where the CI855K01 holds value. While newer Ethernet-based modules exist, this one remains widely supported by ABB and compatible with thousands of installed nodes globally. Replacing it with non-OEM alternatives can introduce compatibility issues—something engineers usually discover too late. Also, spare units tend to hold their resale value well, which matters if your site keeps backup inventory. Another point: firmware updates are managed through standard Control Builder M, so no extra training is needed for your team.

Installation & Maintenance

Mounting is straightforward—it slides into any AC 800M main or expansion cabinet using the standard adapter. Just make sure the grounding is solid; poor grounding has been known to cause intermittent communication faults. Ventilation should allow at least 50mm clearance above and below, especially in warmer environments. For maintenance, check the LED status monthly and verify redundancy switching during scheduled tests. Calibration isn’t required, but we recommend updating firmware every 18–24 months to stay aligned with system patches. Avoid hot-plugging unless the system is configured for it—some older racks don’t handle it gracefully.

Quality & Certifications

The module carries CE, UL, and RoHS compliance marks, which simplifies cross-border deployments. It’s also tested to meet IEC 61131-2 standards for industrial programmable controllers. We offer a 365-day warranty on all units—whether new surplus or refurbished—as long as they haven’t been modified or improperly installed.

Order Placement & Guarantees

Delivery: Most in-stock orders ship within one week. For out-of-stock or customized configurations, delivery won’t exceed four weeks. Payment: 50% advance payment required; balance due before shipment. Shipping: Typically via FedEx, UPS, or DHL depending on destination and urgency. All units are tested prior to dispatch and packed in anti-static, shock-resistant containers.