This scenario walks through a typical UK remote monitoring deployment: a rural pumping station with an existing RTU communicating via Modbus RTU over RS485, no fixed-line broadband available, and a requirement to connect to a central SCADA system at the control centre 40 miles away.
Site Assessment
The pumping station has a Modicon M340 PLC running the local control logic, outputting Modbus RTU on an RS485 bus at 9600 baud. The site has 240V mains power. There is no fixed-line broadband at the site – the nearest exchange is 8km away on a rural line. A multi-network SIM survey shows EE and Vodafone signals both present at -85dBm RSRP, adequate for reliable 4G LTE.
Hardware Specified
- Milesight UR35 router (RS485 Modbus gateway, dual SIM, -40 to +70°C)
- Multi-network fixed IP SIM x 2 (EE primary, Vodafone backup)
- 12V DC power supply for the router (mains-powered from site supply)
- DIN rail mount for installation in the existing panel
Configuration
The UR35 RS485 interface is set to 9600 baud, 8N1 to match the PLC. The Modbus gateway is enabled in RTU-to-TCP mode. The primary SIM APN is configured with the fixed IP details from the SIM supplier. OpenVPN client is configured with the certificate and server address of the VPN concentrator at the control centre. Dual SIM failover is configured with ping monitoring to the SCADA server IP. DeviceHub is registered and the unit added to the estate management group.
Commissioning
The SCADA engineer at the control centre adds the new outstation to the polling configuration, pointing to the fixed IP address of the UR35 on port 502. A test poll confirms Modbus register reads from the PLC. All monitored values update correctly in the SCADA display. The installation team verifies the DeviceHub status shows the unit online and the OpenVPN tunnel active before leaving site. Total installation time: 2.5 hours including travel within the site.
Ongoing Management
All ongoing management is remote via DeviceHub. The network operations team monitors cellular signal strength, uptime, and SIM failover events. When a firmware update is released, it is pushed to the unit remotely via DeviceHub without requiring a site visit. The configuration is backed up in DeviceHub and can be restored to a replacement unit in under 5 minutes if the router ever needs replacing.