Westermo MDW-45: Industrial-Grade RS-232 to RS-422/RS-485 Serial Converter

1. Product Overview

The Westermo MDW-45 is a rugged, DIN-rail-mounted RS-232 to RS-422/RS-485 serial interface converter from Westermo (an Ependion company). Designed for harsh industrial, rail, and heavy-duty environments, it provides reliable protocol-transparent conversion between standard RS-232 and multi-drop or point-to-point RS-422/RS-485 buses.

Available in two versions — MDW-45 LV (low-voltage DC) and MDW-45 HV (high-voltage AC/DC) — the MDW-45 delivers galvanic isolation, transient suppression, and automatic direction control on 2-wire half-duplex RS-485 links. It is fully compatible with Westermo’s marine automation platforms (including K-Chief series, RCU502, RMP200-8, and ABB/Metso integration) for reliable serial data communication to legacy PLCs, drives, HMI panels, and instrumentation in offshore vessels, FPSOs, drillships, and offshore platforms. With no moving parts and an MTBF of 1,000,000 hours (per MIL-HDBK-217K), the MDW-45 ensures continuous operation in the harshest maritime conditions.

2. Core Technical Specifications

The MDW-45 is engineered for extreme reliability and ease of installation in marine-grade applications:

Interfaces: 1 x RS-232 (9-pin D-sub female DCE) and 1 x RS-422/RS-485 (4-position detachable screw terminal).
Data Rates: Up to 115.2 kbit/s (RS-232); 300 bit/s to 115.2 kbit/s (RS-422/RS-485).
Data Format: 7 or 8 data bits, odd/even/none parity, 1 or 2 stop bits (RS-232); code-independent and protocol-transparent.
Power (MDW-45 LV): 9.6–57.6 VDC (rated 12–48 VDC), ~95 mA @ 12 VDC.
Power (MDW-45 HV): 85.5–264 VAC / 88–300 VDC (rated 95–240 VAC / 110–250 VDC), ~21 mA @ 95 VAC.
Isolation & Protection: Full galvanic isolation (tri-galvanic where applicable), transient suppression, over-voltage protection up to ±60 V.
Bus Features: Automatic RTS/data-flow or data-only direction control on 2-wire RS-485; selectable 120 Ω termination & failsafe biasing; 2- or 4-wire support.
LED Indicators: RS-232 data (TX/RX), RTS/CTS status, and power status.
Configuration: DIP switches accessible under lid for all settings.
Environmental & Safety: Operating temperature –40 °C to +70 °C (–40 °F to +158 °F); IP21 protection; vibration 7.5 mm (5–8 Hz) / 2 g (8–500 Hz) and shock 15 g (11 ms) per IEC 60068; EMC EN 61000-6-2/-4; railway approved (EN 50121-4).
Mounting & Dimensions: Horizontal 35 mm DIN-rail (integral clip); 35 mm (W) x 121 mm (H) x 119 mm (D); 0.19 kg.
Certifications: CE, UL, cULus, ATEX Zone 2/22, IECEx, Marine (ABS, DNV-GL, LR, BV), RoHS compliant.

All components are industrial-grade with no moving parts for maximum longevity in marine environments.

3. Key Features & Advantages

The Westermo MDW-45 stands out for its uncompromising reliability and simplicity:

Automatic Bus Control: No handshaking required — data flow automatically switches direction on 2-wire RS-485, compatible with equipment lacking RTS/CTS.
Seamless Integration: Direct drop-in compatibility with Westermo K-Chief RCU502, RMP200-8 I/O modules, and ABB/Metso S800 systems for marine automation retrofits or newbuilds.
Rugged Marine Design: Full salt-mist qualification, vibration/shock resistance, and extended temperature range make it ideal for ships, FPSOs, and offshore platforms.
Easy Configuration & Maintenance: DIP switches + clear labeling + hot-swap friendly in most cabinets; built-in diagnostics reduce troubleshooting time.
High Availability: 1,000,000-hour MTBF ensures minimal downtime; hot-replacement possible without system interruption in redundant setups.

These features deliver rock-solid serial communication in environments where legacy RS-232/RS-485 equipment still powers critical marine control loops.

4. Applications & Real-World Value

The Westermo MDW-45 is the preferred serial bridge for Westermo and multi-vendor marine automation systems:

Dynamic Positioning & Propulsion (K-Pos / K-Thrust) — Direct interface for legacy RS-232/485 sensors and actuators in DP Class 3 operations.
Vessel Management & Safety Systems (K-Chief 700 / K-Safe) — Reliable connection of PLCs, drives, and HMI panels in machinery spaces and control rooms.
Offshore Platforms & FPSOs — Communication with ABB 800xA, Metso/Valmet DCS, and third-party instrumentation in extreme environments.
Marine Retrofit & Newbuild — ABS/DNV-GL/LR type-approved for ships, support vessels, and special-purpose platforms.
Industrial Legacy Integration — Bridges RS-232/485 devices in harsh marine or rail-trackside settings.

By selecting the genuine Westermo MDW-45, shipowners, plant operators, and integrators gain a proven, catalog-listed component that protects expensive assets, meets strict classification-society requirements, and delivers the rock-solid performance that Westermo’s industrial converters are renowned for worldwide.

Need a customized product description, comparison with MDW-45 LV vs. HV or similar serial converters (e.g., MD-52, MD-21), technical datasheet excerpt, or a version tailored for a specific marine automation platform or industry? Just let me know — happy to refine it further!