Industrial cellular WAN for SCADA and remote monitoring replaces legacy PSTN, leased line and dialup connections with reliable 4G and 5G connectivity. The Milesight UR series provides the complete solution: RS485 Modbus gateway, fixed IP SIM support, VPN tunnel, dual SIM failover, and DeviceHub remote management.
The Core Architecture
A SCADA outstation using a Milesight UR75 consists of the industrial router connected to field devices via RS485 (for Modbus RTU devices) and Ethernet (for IP-based devices). The router establishes a cellular WAN connection using a fixed IP SIM, creates a VPN tunnel to the control centre, and makes field device data available to the SCADA host as if the remote site were on the local network. The SCADA software polls Modbus TCP on port 502 – the router handles all RS485 to TCP conversion transparently.
Key Features for SCADA Applications
- RS485 Modbus gateway – built into UR75 and UR35 firmware, no separate converter hardware needed
- Fixed IP SIM – permanent IP address for reliable SCADA polling and inbound connectivity
- VPN client – OpenVPN, IPsec or WireGuard tunnel to the control centre
- Dual SIM failover – automatic network switching in under 60 seconds
- Hardware watchdog – automatic reboot on connection failure, no site visits required
- Industrial temperature range – -40 to +70°C, suitable for unheated outdoor cabinets
- DeviceHub – remote configuration and monitoring across the full estate
Recommended Products
Milesight UR75 – 5G with RS485, dual SIM, full SCADA feature set
Milesight UR35 – 4G with RS485, dual SIM, for sites where 5G is not required