BUYING GUIDE · INDUSTRIAL
Modbus Data Loggers: Legacy Plant to Cloud, No PLC Surgery
Your plant already measures everything — the data just dies inside a panel. Modbus bridges lift those registers to the cloud without touching the control logic.
The data is already there. Free it.
A modbus data logger solves industry’s most common data problem: the meters, drives, chillers and gensets on site already expose everything over Modbus RS485, but the values live and die inside the panel. Bridging those registers to a dashboard needs no changes to the PLC, no controls contractor and no downtime — read-only polling is invisible to the process.
The devices below span the spectrum: a pocket-sized modbus data logger that turns any RS485 slave into a LoRaWAN sensor, controller-class units that poll many devices with local I/O, and — for the truly stranded — AI cameras that read the analogue dial no protocol will ever reach.
The Modbus data logger line-up
Pick by how many devices you are polling and what else the point needs (I/O, power control, cellular). All land in the same dashboards as every sensor on this site.
One device, one bridgeMilesight UC100 IoT ControllerThe pocket bridge: polls one RS485 Modbus slave — a meter, a drive, a chiller — and reports it over LoRaWAN. Extraordinary value.
£38.90 ex VATView →
Panels & multiple slavesMilesight UC300 IoT ControllerController-class unit polling multiple Modbus devices with DI/DO/AI on board — the panel-level aggregator.
From £104.74 ex VATView →
Field I/O + ModbusMilesight UC501 IoT ControllerRugged outdoor controller for pits, kiosks and field cabinets: Modbus plus analogue and digital I/O, battery or solar friendly.
From £119.71 ex VATView →
More I/O headroomMilesight UC502 IoT ControllerThe bigger-I/O sibling for pump stations and instrument clusters.
From £122.70 ex VATView →
Serial + connectivityMilesight UR35 Industrial Cellular RouterThe industrial router with serial on board — where the site needs its WAN and its Modbus bridging in one box.
From £149.63 ex VATView →
Dials & gauges (AI)Milesight X1 Sensing CameraSensing camera that photographs and AI-reads analogue gauges, dials and counters — data from instruments with no interface at all.
From £62.85 ex VATView →Compare bridging options
| Product | Best for | Connectivity | Price (ex VAT) |
|---|---|---|---|
| Milesight UC100 IoT Controller | Single RS485 slave | LoRaWAN® | £38.90 |
| Milesight UC300 IoT Controller | Multi-slave panels + I/O | LoRaWAN® / cellular options | From £104.74 |
| Milesight UC501 IoT Controller | Field cabinets, outdoor | LoRaWAN® | From £119.71 |
| Milesight UC502 IoT Controller | Pump stations, more I/O | LoRaWAN® | From £122.70 |
| Milesight UR35 Industrial Cellular Router | Serial + site WAN | 4G LTE | From £149.63 |
| Milesight X1 Sensing Camera | Analogue dial reading | Wi-Fi / LoRaWAN options | From £62.85 |
Scoping the bridge in four questions
One: how many slaves, and where? A single meter takes a UC100; a panel of five takes a UC300; scattered field devices take one bridge each rather than heroic cable runs. Two: read-only or control? Polling registers is zero-risk; if the point should also switch things (a pump interlock, a valve), the controller class brings relays and I/O — keep safety functions in the PLC where they belong.
Three: what carries the data out — the site’s LoRaWAN gateway, or cellular where no network exists? Four: what cannot speak Modbus at all? Old gauges, sight glasses and mechanical counters are exactly what the sensing cameras exist for — an AI camera reading the dial beats a £10k instrument replacement every time. A modbus data logger programme usually mixes all four answers across one site.
- Read-only polling is invisible to the PLC and the process
- UC100 per stranded meter; UC300 per multi-device panel
- Registers you’ll want: energy, runtime hours, alarms, setpoint drift
- Keep safety interlocks in the PLC — the bridge reports, it doesn’t protect
- Sensing cameras rescue instruments with no interface at all
- Same dashboards as every sensor here — plant and sensors in one view
Wiring it into the estate
Bridges join the site’s LoRaWAN gateway like any sensor; isolated sites use the cellular router path instead. Commissioning is registers-and-scaling work we can pre-configure against your device list — send the meter and drive models and units arrive ready to wire.
The classic first project is energy: bridge the fiscal and sub-meters (see the energy monitoring guide — CTs cover what has no meter), then runtime and alarms from critical plant. The SCADA & remote I/O solution shows the full architecture.
Why buy from Indiott
Everything here ships from UK stock with GBP pricing and a human on the end of the phone. If you are rolling out across multiple sites, ask for volume pricing — quotes normally come back within one working day.
Frequently asked questions
Will polling Modbus interfere with our PLC or BMS?
No — Modbus reads are passive register requests, the same traffic your HMI already generates. The bridge sits on the RS485 line as one more polite master or spur (we will advise on topology), and the control logic never knows it is there. Write/control functions are only enabled if you explicitly want them.
What if our devices use Modbus TCP rather than RTU?
The controller-class units and routers handle both — TCP devices are polled over Ethernet, RTU over RS485, and mixed sites are normal. Send the device list and we will map which unit polls what before anything ships.
Can you pre-configure the register maps?
Yes — tell us the make and model of each meter, drive or chiller and the values you care about, and units arrive with registers, scaling and units configured. On site it is wire, power, verify — typically minutes per point.
How do the gauge-reading cameras actually work?
The camera photographs the dial on a schedule and on-device AI converts needle position or digits into a numeric reading, which then flows into the dashboard like any other value. It is the pragmatic answer for instruments that predate digital interfaces — no shutdown, no replacement, no fitter.
Free the data from one panel first
Send us your device list — makes, models, counts — and we will spec the modbus data logger mix, pre-configured, with pricing within one working day.
Next step
Scope it with an engineer.
Tell us the site, the assets and the constraint. You get a bill of materials and a straight answer within one working day.
- A bill of materials sized to your site
- Priced ex VAT, UK entity, no login wall
Rather talk it through? Call 023 9223 3611
Received. An engineer has it.
You will hear back within one working day with the parts, the prices and the lead time. A confirmation is on its way to your inbox.
If it is urgent, call 023 9223 3611.
More buying guides