Description:
The ABB 3BDZ000398R1, also designated as RLM01, is a PROFIBUS DP Redundancy Link Module within ABB’s Symphony™ Plus (formerly Symphony Harmony / INFI 90 Open) distributed control system family. It provides a dual-channel, redundant PROFIBUS DP/V1 interface that connects the DCS I/O rack (via the backplane) to a PROFIBUS fieldbus network—typically a redundant cable pair (Cable A / Cable B). The RLM01 enables bumpless switchover in the event of a cable fault or segment failure, ensuring continuous communication between the controller and PROFIBUS field devices (ABB S800 I/O, drives, analyzers, etc.) without process interruption.h2 Application Scenarios:A petrochemical cracker unit running an ABB Symphony Harmony DCS had its single-cable PROFIBUS segment to a bank of ABB S800 remote I/O and smart-variable-frequency drives severed during unrelated cable-tray maintenance, causing a unit trip. During the subsequent modernization, the plant added the ABB 3BDZ000398R1 (RLM01) Redundancy Link Module in each affected I/O rack, configured for PROFIBUS DP-V1 with redundant cable topology (A+B). When a similar cable damage occurred on Cable A six months later, the RLM01 automatically switched to Cable B in < 10 ms—process control was maintained, no alarm escalation occurred, and operators saw only a minor “Segment A Fault” advisory. The 3BDZ000398R1 directly addressed the pain point of single-point-of-failure fieldbus wiring, elevating the plant’s process availability metric and satisfying the corporate HA (High Availability) standard for critical loops.h2
Parameter:
| Main Parameters | Value/Description |
|---|---|
| Product Model | 3BDZ000398R1 (also listed as RLM01) |
| Manufacturer | ABB (ABB Process Automation — Symphony Plus / Harmony INFI-90 Family) |
| Product Category | PROFIBUS DP Redundancy Link Module (RLM Series) |
| Fieldbus Protocol | PROFIBUS DP / DP-V1 (Slave to the PROFIBUS Master; acts as interface between DCS rack & fieldbus) |
| Redundancy Feature | Dual PROFIBUS cable ports (A & B) — Automatic bumpless switchover on cable/segment failure |
| Backplane Interface | Plugs into Symphony Harmony / INFI-90 I/O rack — communicates with NPM / Controller via rack bus |
| Transmission Rate | 9.6 kbps – 12 Mbps (auto-negotiated with PROFIBUS master) |
| Connector Type | 2 × DB9 Female (PROFIBUS A + B) per IEC 61158 |
| Power Requirement | Via DCS rack backplane (typically 5 V DC @ ≈ 0.8–1.2 A) |
| Hot-Swap Capable | Yes — Module can be replaced under power in supported rack configurations |
| Operating Temp. | 0 °C to +60 °C (some references cite -20 °C to +70 °C) |
| Protection Rating | IP20 (installed inside enclosed control cabinet / rack) |
| Certifications | CE, cULus, PROFIBUS International (PI) Certified |
h2 Technical Principles and Innovative Values:
- Transparent Redundant PROFIBUS Segment Management: The RLM01 continuously monitors both PROFIBUS cables (A and B). Under normal conditions both are active; if one cable is cut, shorted, or its segment loses power, the module silently switches to the healthy cable and reports the fault to the DCS—without dropping cyclic data or requiring controller intervention. This transparency is key to meeting SIL / HA requirements in continuous-process industries.
- Native Harmony / INFI-90 Backplane Integration: Unlike stand-alone PROFIBUS interface cards that require a PC or separate gateway, the 3BDZ000398R1 seats directly in the DCS I/O rack and is configured through ABB Composer / SysCon engineering tools. I/O point mapping, diagnostics, and alarm propagation are handled by the existing DCS database—no extra software or protocol converters needed.
- Comprehensive On-Board Diagnostics: Front-panel LEDs display module status (RUN / ERR / BF / SF), PROFIBUS baud rate detection, and cable-A / cable-B health. The RLM01 also pushes detailed diagnostic telegrams (telegram loss, slave not reachable, cable fault) to the DCS alarm summary, enabling field technicians to pinpoint bus faults without a PROFIBUS analyzer.
h2 Application Cases and Industry Value:Case 1 – Oil Refinery CDU/SRU FCCU DCS Fieldbus Upgrade:A refinery modernized its FCCU reactor-section field instrument network from parallel hard-wiring to PROFIBUS DP-V1 with ABB S800 I/O. Two ABB 3BDZ000398R1 (RLM01) modules were installed—one per redundant I/O rack—providing A/B cable redundancy to all 14 S800 stations. During a later cable-tray fire-suppression test, one PROFIBUS trunk was intentionally disconnected; the RLM modules switched over transparently and the process was unaffected. The refinery subsequently standardized all new PROFIBUS segments on the RLM01 for consistent redundancy architecture.
