Inline Isolator Safeguards Modbus RTU Wiring in High-Noise Industrial Systems

Banner Targets a Persistent Weak Point in Serial Networks

Banner Engineering has introduced the S25GI galvanic isolator, a compact inline device developed to protect RS485 and Modbus RTU communication networks from electrical interference and grounding faults. While Ethernet-based protocols continue expanding across factories, RS485 remains deeply embedded in industrial infrastructure due to its simplicity, reliability, and low implementation cost.

In many brownfield facilities, however, serial communication lines operate near variable frequency drives, motor starters, and high-voltage equipment. These environments generate electromagnetic interference that can corrupt communication signals or damage connected devices. Banner’s S25GI addresses these issues without requiring additional cabinet space or extensive rewiring.

The S25GI provides inline protection for Modbus RTU and RS485 communication networks exposed to electrical noise and surge conditions.

Why RS485 Still Matters in Modern Automation

Despite the rapid adoption of Industrial Ethernet, RS485 and Modbus RTU continue supporting countless industrial devices, including sensors, VFDs, distributed I/O modules, and legacy PLC systems. Many facilities still depend on these networks because they are stable, inexpensive, and widely supported across multiple automation vendors.

Manufacturers integrating serial communication devices with modern control systems often combine them with platforms such as Allen-Bradley ControlLogix or distributed architectures based on industrial communication networking hardware. In these hybrid environments, signal integrity becomes increasingly important.

Electrical Noise Creates Real Operational Risks

RS485 communication relies on low-voltage differential signaling. Although the protocol performs well across long cable distances, it remains vulnerable to electrical noise generated by nearby power systems. Large VFD installations, servo systems, and motor switching events can inject transient noise directly into communication lines.

Ground loops create another common failure mechanism. When multiple devices use different grounding paths, voltage differences can appear between system components. These unwanted currents introduce communication instability and may eventually damage sensitive electronics.

The S25GI can mount directly near field devices, reducing installation complexity during machine retrofits.

Inline Isolation Without Consuming Cabinet Space

Traditional galvanic isolators typically require DIN-rail mounting inside electrical cabinets. That approach increases enclosure crowding and adds wiring complexity during upgrades. Banner instead designed the S25GI as an inline module with rugged IP67-rated connectors for direct installation near machines or field devices.

The isolator supports Modbus RTU and RS485 networks while allowing 200 mA power pass-through for connected sensors, indicators, or remote I/O devices. This design simplifies field integration because installers can protect communication lines without adding external power distribution hardware.

Flexible Deployment for Retrofit Projects

The compact isolator can protect a single sensor connection or shield an entire communication segment near the network hub. This flexibility is especially useful during modernization projects where older machinery gains new VFDs, smart sensors, or remote monitoring devices.

Facilities upgrading motion systems with newer drives and motion control platforms frequently encounter communication instability after retrofit work. Inline isolation helps engineers reduce troubleshooting time while preserving existing serial infrastructure.

Serial communication networks often operate alongside high-power equipment inside crowded industrial control cabinets.

Industrial Trend: Protecting Legacy Infrastructure Instead of Replacing It

One of the most important shifts in industrial automation is the growing investment in retrofit strategies instead of full system replacement. Many factories cannot justify replacing functioning RS485 infrastructure simply to achieve higher communication speeds.

Instead, engineers increasingly focus on strengthening network reliability while extending equipment life. Products like the S25GI reflect this strategy by solving communication weaknesses without forcing large-scale architecture changes.

From an engineering perspective, this approach makes practical and financial sense. A stable Modbus RTU network with proper isolation can continue operating reliably for many years, particularly in packaging lines, water treatment facilities, material handling systems, and process skids.

Author Opinion

The strongest aspect of the S25GI is not its isolation performance alone. Its real value comes from deployment simplicity. Many communication protection products still assume abundant cabinet space and easy field rewiring, conditions rarely found in operating plants.

Banner recognized a practical maintenance problem and delivered a field-oriented solution that aligns with modern retrofit realities. As industrial facilities continue mixing legacy serial networks with newer automation hardware, compact inline isolation devices will likely become standard practice rather than optional accessories.

Oliver Grant | Senior Industrial Systems Reporter

Oliver Grant has 14 years of experience covering industrial automation, machine networking, and control system modernization. His background includes field integration projects involving Rockwell Automation, Siemens, Beckhoff Automation, and Emerson process systems across manufacturing and energy facilities.