B+W BWU1703 Replacement Upgrade Solution for BWU Series

Product Overview

B+W BWU1703 Replacement Upgrade Solution for BWU Series: Seamless Transition from Legacy PROFIBUS Infrastructure

The B+W BWU1703 is a high-performance PROFIBUS DP/PA Segment Coupler engineered by Bihl+Wiedemann for industrial automation environments where reliable fieldbus communication is mission-critical. As legacy PROFIBUS DP/PA infrastructure ages and original segment couplers reach end-of-life or become difficult to source, the BWU1703 serves as a direct replacement and functional upgrade solution for engineers managing distributed control systems, process automation networks, and field device integration projects.

Whether you are migrating from an older Bihl+Wiedemann BWU1702 or BWU1700 segment coupler, replacing a failed unit in a Siemens S7-300 or S7-400 PROFIBUS network, or upgrading a legacy DCS fieldbus segment to improve signal integrity and diagnostic capability, the BWU1703 delivers the electrical isolation, impedance matching, and protocol conversion required for a smooth, low-downtime transition. Its compact DIN-rail form factor and standard 24 VDC power supply input make it physically compatible with most existing control cabinet layouts without requiring panel modifications.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful PROFIBUS DP/PA segment coupler replacement rarely involves a single component. In practice, field engineers upgrading from a legacy BWU1700 or BWU1702 to the BWU1703 will also evaluate the surrounding infrastructure to ensure end-to-end communication integrity. On the DP backbone side, the BWU1703 connects directly to the PROFIBUS DP master — commonly a Siemens CP 342-5 or CP 443-5 communication processor installed in an S7-300 or S7-400 rack. Ensuring the DP cable termination resistors are correctly set at both ends of the segment remains essential after any coupler swap.

On the PA segment side, the BWU1703 powers and communicates with PROFIBUS PA field devices such as pressure transmitters, flow meters, and level sensors from manufacturers including Endress+Hauser, Yokogawa, and ABB. When replacing the coupler, engineers should verify that the total PA segment current draw — across all connected field devices — does not exceed the BWU1703’s rated output. If the existing PA segment was previously powered by a separate PA power conditioner or segment protector, the BWU1703’s integrated power feed may allow consolidation, simplifying the cabinet layout.

For installations where the PROFIBUS DP backbone runs through a Bihl+Wiedemann BWU3xx series AS-Interface/PROFIBUS gateway or where the control system includes a Siemens ET 200M distributed I/O station with IM 153-2 interface module, the BWU1703 integrates without protocol conflicts. The coupler’s transparent DP/PA conversion means the PLC program — whether running on a Siemens S7-300, S7-400, or a third-party PROFIBUS DP master — requires no modification to the existing function block or hardware configuration beyond updating the physical slot assignment if the coupler’s GSD identity differs from the predecessor model.

In control cabinets where space is constrained, the BWU1703’s slim DIN-rail profile allows it to be installed alongside standard 24 VDC SITOP power supply modules, PROFIBUS DP bus connectors with integrated termination (such as the Siemens 6ES7 972-0BA52-0XA0 style connectors), and PA field barrier or segment protector modules without requiring panel redesign. For multi-segment PROFIBUS PA networks, multiple BWU1703 units can be deployed in parallel on the same DP backbone, each serving an independent PA segment — a common architecture in process plants with geographically distributed field devices.

Engineers performing a full fieldbus modernization may also be sourcing PROFIBUS PA terminator plugs, shielded twisted-pair PA segment cables (type A, IEC 61158-2 compliant), and DIN-rail terminal blocks for signal segregation. These ancillary components, combined with the BWU1703, form a complete, standards-compliant PROFIBUS DP/PA infrastructure upgrade that extends system service life without requiring migration to Industrial Ethernet or PROFINET — preserving the existing investment in PA field instrumentation and PLC programming.

Retrofit Guidance FAQ

Q: Can I replace a BWU1700 or BWU1702 with the BWU1703 without rewiring the PA segment?
A: In most cases, yes. The BWU1703 uses the same screw-terminal wiring convention for the PROFIBUS DP bus connection and the PA segment output. Verify terminal labeling against your existing wiring diagram before powering up. No changes to PA field device wiring are required.

Q: Do I need to update the GSD file in my PROFIBUS DP master configuration?
A: If the BWU1703’s GSD identifier differs from the predecessor model, you will need to import the BWU1703 GSD file into your engineering tool (e.g., Siemens STEP 7 or TIA Portal hardware configurator) and reassign the slot. The PLC program logic itself does not require modification — only the hardware configuration layer is affected.

Q: Is the BWU1703 compatible with all PROFIBUS DP master classes?
A: Yes. The BWU1703 is compatible with PROFIBUS DP Class 1 masters (cyclic data exchange) and Class 2 masters (acyclic parameterization and diagnostics), making it suitable for use with Siemens, Schneider Electric, ABB, and other third-party PROFIBUS DP controllers.

Q: What is the maximum number of PA field devices supported per BWU1703 segment?
A: This depends on the current consumption of each PA device. The BWU1703 supplies up to 400 mA to the PA segment. Typical PROFIBUS PA field devices consume between 10 mA and 25 mA each, allowing 10–30 devices per segment under normal conditions. Always calculate the total segment current budget before commissioning.

Q: Can the BWU1703 be used in hazardous area (Ex) applications?
A: The standard BWU1703 is designed for installation in the safe area (control cabinet side). For intrinsically safe PA segments in Zone 1 or Zone 2 hazardous areas, a certified PROFIBUS PA segment protector or field barrier must be used between the BWU1703 and the Ex field devices. Consult the applicable ATEX or IECEx documentation for your installation.

Q: What diagnostic information does the BWU1703 provide?
A: The BWU1703 features LED indicators for DP bus activity, PA segment status, power supply presence, and fault conditions. These allow rapid on-site diagnosis of communication interruptions, short circuits on the PA segment, or power supply failures without requiring a laptop or diagnostic tool.

Warranty Assurance

Every B+W BWU1703 PROFIBUS DP/PA Segment Coupler supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes functional verification including power-up testing, DP/PA communication path validation, and visual inspection for physical integrity. Units that do not meet our quality standards are not shipped.

In the event of a confirmed defect within the warranty period, TOPNLMS provides replacement support with priority processing to minimize your system downtime. Our after-sales response team is reachable via email at [email protected] or by phone at +86 18359293191. We maintain stock of the BWU1703 and related PROFIBUS components to support rapid fulfillment for both planned procurement and emergency replacement scenarios.

All units are shipped from our Xiamen warehouse with appropriate ESD-protective packaging and export documentation. Lead times for in-stock units are typically 3–7 business days for international destinations. For large-quantity orders or project-based procurement, please contact our sales team directly for a formal quotation and delivery schedule.

TOPNLMS is committed to supporting industrial automation engineers with reliable, spec-accurate components and responsive technical assistance throughout the procurement and commissioning process.