Modbus Gateway

What a Modbus Gateway Actually Does on Site

A Modbus gateway sits between your serial fieldbus and your IP network. It translates Modbus RTU frames from RS232 or RS485 devices into Modbus TCP/IP packets — so SCADA systems, HMIs, and cloud dashboards can read and write registers on legacy equipment without any changes to the field devices themselves.

This is the standard approach for modernising factories, utilities, and building systems: keep the instruments and drives that are working, upgrade the data layer. The result is centralised monitoring, faster diagnostics, and a controlled path to IIoT connectivity.

• Legacy Modbus RTU energy meters connected to BMS or SCADA via Ethernet
• RS232 PLCs integrated into an IP control network without rewiring
• RS485 sensors at remote sites made accessible for cloud-based diagnostics
• Industrial retrofits where replacing field devices is not cost-justified

Compare Sollae Modbus TCP Gateway Models

All four models perform the same core job — Modbus RTU to Modbus TCP conversion — but differ in field interface, network connection, and protection level. Use the table to match the model to your environment.

How to Choose the Right Modbus RTU to TCP Gateway

The right Modbus TCP gateway depends on four variables: field interface, network type, electrical environment, and security requirement. Work through this checklist before ordering.

1. Field interface: RS232 only → SMG-5410. Multi-drop RS485 Modbus bus → SMG-5420 or SMG-5620.
2. Network connection: Fixed Ethernet infrastructure → any wired model. No cable route available → SMG-5400 (Wi-Fi).
3. Electrical environment: Ground potential differences, surge risk, or high electrical noise → SMG-5620 (isolated, steel case).
4. Security requirement: All models support password protection. Wi-Fi deployments → SMG-5400 with WPA2 or WPA-Enterprise for site network compliance.
5. Multi-host access: If SCADA, HMI, and a monitoring service all need simultaneous access, confirm the model supports up to 4 TCP connections.
6. Rollout scale: Standardise on one model family across sites to simplify spares inventory, documentation, and commissioning procedures.

Ethernet Modbus Connectivity: Key Specifications

All Sollae gateways in this range support Ethernet Modbus TCP/IP (IPv4/IPv6 dual stack) and are designed for straightforward commissioning in IT/OT environments. Below are the shared capabilities relevant to integration projects.

• Protocol conversion: Modbus RTU ↔ Modbus TCP/IP (serial-to-Ethernet, bidirectional)
• TCP connections: Up to 4 simultaneous channels — supports SCADA + HMI + monitoring in parallel
• IP stack: IPv4 and IPv6 dual stack for network standardisation across mixed infrastructure
• Serial speeds: Configurable baud rate to match existing fieldbus settings
• Protection (model-dependent): TVS diodes, bias resistors, electrical isolation, over-voltage protection
• Wi-Fi security (SMG-5400): WPA, WPA2, and WPA-Enterprise for enterprise network compliance