The RS422/RS485 Isolator Industry with surge protection from Wiesemann & Theis is a high-quality interface solution for industrial applications. In addition to galvanic isolation with a 1 kV DC isolation voltage, it features an integrated surge protection system that limits harmful differential voltages to ±9 V through fast protection diodes. This prevents damage to sensitive interface components, especially in outdoor installations or uncertain wiring conditions.

With transmission speeds up to 3 MBaud, automatic RS485 control, and transparent operation, the isolator is the ideal choice for networked systems in Industry 4.0, automation environments, and building management systems.

Galvanic isolation with additional surge protection

Galvanic isolation between two RS422/RS485 interfaces prevents equalizing currents that could interfere with the operation of sensitive control circuits. In industrial environments, grounding connections through control buses or host PCs can lead to unstable control loops and device failures.

The integrated surge protection prevents damage caused by voltage spikes, which may result from:

• Lightning strikes on outdoor lines
• Switching operations of high-power consumers
• Inductive coupling along long cable runs

Fast protection diodes limit differential voltages to ±9 V—well below the typical destruction threshold of RS485 transceivers (±12–14 V).

High data rates and interface flexibility

The isolator is equipped with two 9‑pin Sub‑D connectors, enabling flexible connection to RS422 and RS485 devices. It supports:

• RS422 – point-to-point communication with high noise immunity
• RS485 – multi‑point bus systems with automatic control

With data transmission rates up to 3 MBaud, it is suitable for data‑intensive applications where both speed and reliability are essential.

Transparent operation without configuration

The isolator operates fully transparently—parameters such as baud rate, parity, or stop bits do not need to be configured. This minimizes installation effort and ensures compatibility with a wide range of existing systems.

Power supply and energy efficiency

Power is supplied via a galvanically isolated screw terminal (12–24 V AC/DC). This isolation in the power input enhances system safety and prevents unwanted equalizing currents.

• Flexible use of different power sources
• Energy-efficient architecture for continuous operation
• Surge protection without compromising energy efficiency

Standards compliance and robust design

The isolator meets the following standards:

• EN 61000‑6‑2 – Immunity
• EN 55032:2015 + A1 Class B – Emissions
• EN 61000‑3‑2 / EN 61000‑3‑3 – Electromagnetic compatibility

CE and UL certifications confirm global usability. The industrial-grade construction is designed for continuous operation and comes with a five‑year warranty.

Typical applications

• Outdoor installations: Protection of RS485 sensors and controllers against lightning-induced surges.
• Industrial automation: Reliable communication in complex bus systems.
• Building management systems: Secure connection between distributed control nodes.
• Data acquisition: Stable data transmission across long cable distances.

Advantages of DIN rail mounting

The DIN rail housing allows:

• Space-saving integration into control cabinets
• Clean cable organization
• Quick installation and easy maintenance

Maximum safety for RS422/RS485 networks

The RS422/RS485 Isolator Industry with surge protection combines galvanic isolation with effective overvoltage protection. This ensures not only system stability and safety but also user-friendly operation in industrial bus systems. Its rugged design, automatic RS485 control, and compliance with strict EMC standards make it an ideal interface solution for Industry 4.0 and beyond.