# Modbus Monitoring: Bridge to Cloud Dashboards (https://logable.app/solutions/modbus-monitoring)

Bridge Modbus RTU and TCP devices to live cloud dashboards through a gateway. Watch every register update and get alerted when a value crosses a limit.

A gateway reads the pressure transmitter over Modbus and sends each reading out over one encrypted connection. Nothing is written back, and nothing on the skid opens a port.

## Every Modbus device on one list.
Flow Meter 12 reports 41.2 m³/h. The gateway reads it the same way it reads a drive, a scale or a sensor, whether the device speaks Modbus RTU or Modbus TCP.
- **One dashboard for every device** Flow meters, drives, scales and sensors, all on the same screen.
- **Know when one drifts** Set a limit on any value. The right person gets the reading before the line stops.
- **Nothing on the internet** The gateway sends readings out over one encrypted connection. Nothing comes in.

## Devices that already speak Modbus
Each type comes with the metrics and dashboard widgets already set up. Add a device and it just works.
- **Silos** A silo running low books its own delivery. Fill level and weight, on the same dashboard as everything else.
- **Conveyors** A stopped belt does not wait to be found. Belt scale throughput, belt speed and a running total.
- **Motors** A drive tells you before it trips. RPM, power draw, temperature and run status.
- **Water pumps** A pump running against a closed valve says so. Flow rate, pressure, power and efficiency.
- **Scales** Every load is weighed on the way out. Weight, with stability and calibration state.
- **Flow meters** A line losing flow is caught before the tank runs dry. Instantaneous and total flow, with direction.
- **Weigh bins** A batch that misses its target is caught on the shift. Batch weighing, with the open and close state.
- **Check weighers** An underweight pack is caught at the line, not at the depot. In-motion weighing and count verification.

## What comes back from a register
The gateway maps registers to named values with units, so a dashboard shows flow rate and temperature rather than register 40001.
| Reading | Unit | What it tells you | Where it comes from |
| --- | --- | --- | --- |
| Instantaneous flow | L/min | whether the line is moving what it should | the meter's holding register |
| Total flow | L | what actually moved this shift | the meter's own totaliser |
| Discharge pressure | bar | a blockage or a closed valve | the pressure transmitter on the skid |
| Drive speed | rpm | a drive slowed or stopped | the VFD's Modbus register |
| Weight | kg | the load on the platform | the indicator's serial output |

## From the meter to the phone
A gateway on your own network reads every Modbus device, serial or Ethernet, and sends each reading to Logable over one encrypted connection. The device never touches the internet.
A flow meter on RS-485 and a pump drive on Ethernet both report to one gateway, over Modbus RTU and Modbus TCP. The gateway publishes to Logable Cloud over MQTT, encrypted.
One gateway handles both wiring types, so a new flow meter or drive is wired to the gateway, not connected to Logable a second way.

## One gateway, both protocols
| Protocol | How it reaches Logable | Notes |
| --- | --- | --- |
| MQTT | Direct to Logable | The gateway publishes every reading to Logable over MQTT with TLS. |
| HTTPS | Direct to Logable | A gateway can post the same readings to the Logable API instead. |
| Modbus RTU | Through a gateway | Serial devices on RS-485 are polled by the gateway on your own network. |
| Modbus TCP | Through a gateway | Ethernet devices are polled by the same gateway. Logable never speaks Modbus itself. |
A gateway on your own network polls RS-485 and Ethernet devices at the interval you set and publishes upward over one encrypted connection.
See how to connect a PLC or a Modbus device via a gateway: https://logable.app/docs/integrate/connect-plcs-and-modbus-via-a-gateway

## Every Modbus device on one screen
Flow meters, drives, scales and sensors on the same dashboard, updating as each poll lands.

> RTU or TCP, the gateway reads it. You never touch the wiring.
>
> Add a flow meter, a drive or a sensor and the same gateway picks it up. Nothing changes on your network.

## A limit on any register
Four rules cover what a Modbus fleet reports going wrong.
- **Low flow** Tells you when flow drops to the low threshold you set on this meter.
- **Over pressure** Tells you when discharge pressure reaches 90 % of the pump’s rated maximum.
- **Belt stopped** Tells you when the belt stops moving. Only add this to a belt that is meant to run continuously. It will also fire on planned stops.
- **Not reporting** Tells you when this device stops sending data, and again when it comes back.

## The reading, wherever you are.
Flow Meter 12 falls to 8.4 L/min at 03:40. The push carries the device and the value, so the decision is made before anyone drives out.

## What goes wrong on a Modbus fleet
Three failures a serial loop cannot tell anyone about on its own.
| What happens | What you see today | What Logable does |
| --- | --- | --- |
| A line loses flow overnight. | The tank is found empty in the morning. | The low-flow alert fires when the meter drops under its limit. · Low flow |
| A pump runs against a closed valve. | The seal fails before anyone reads the gauge. | A phone alert carries the over-pressure reading. · Over pressure |
| A gateway loses power. | Every dashboard on that loop quietly stops moving. | The not-reporting alert names each device that went silent. · Not reporting |

## Modbus RTU vs Modbus TCP
Both protocols are fully supported through IoT gateways. Here is how they compare.
|  | Modbus RTU | Modbus TCP |
| --- | --- | --- |
| Physical Layer | RS-485 serial (wired) | Ethernet / Wi-Fi |
| Speed | Up to 115.2 kbps | 10/100/1000 Mbps |
| Distance | Up to 1,200m (RS-485) | Standard network reach |
| Addressing | Each device has its own address | IP address, plus each device's own address |
| Common Use | Legacy devices, field instruments | Modern PLCs, VFDs, meters |

## What you get with Modbus monitoring
The dashboard, the alerts and the phone, on top of the devices you already have.
- Charts and gauges update the moment a new value arrives from the gateway. Build the layout you need with the dashboard builder.
- Set a limit on any reading. The right person gets it by push, email or the inbox before the line stops.
- The gateway sends readings out over one encrypted connection. No inbound firewall ports, on any device.
- Flow rate, weight, RPM and temperature, not raw register numbers. Each device type comes mapped already.

## What it costs
One gateway can serve a whole RS-485 loop. You pay for the devices you watch.
The trial runs 14 days with 5 devices and Growth features, and asks for no card. Industry plans are quoted per site.
The gateway is bought once from your supplier and is not a Logable cost.

## Frequently asked questions

What teams ask before they connect the first device.

### Does Logable support Modbus natively?
Modbus connectivity is handled through IoT gateways, not built directly into the Logable platform. The gateway reads values from your Modbus devices and sends the data to Logable over MQTT. For other data, Logable also accepts a simple web request.

### What is an IoT gateway and do I need one?
An IoT gateway is a small device or software application that sits on your local network. It reads data from Modbus devices using RS-485 (RTU) or Ethernet (TCP) and forwards it to Logable over the internet via MQTT. Yes, you need a gateway to bridge Modbus devices to the cloud.

### Can I monitor both Modbus RTU and Modbus TCP devices?
Yes. IoT gateways support both Modbus RTU (serial/RS-485) and Modbus TCP (Ethernet). Many gateways can handle both protocols simultaneously, so you can connect legacy serial devices and modern Ethernet-connected equipment through a single gateway.

### How often does data update in Logable?
Data update frequency depends on your gateway configuration. Most gateways can check your Modbus devices every 1 to 10 seconds and send updates to Logable in real time over MQTT. You set the interval on the gateway to balance freshness with network use.

### What Modbus register types are supported?
IoT gateways typically support all standard Modbus register types: coils (discrete outputs), discrete inputs, holding registers, and input registers. The gateway maps these register values to Logable metrics, so you see meaningful data like temperature, weight, or flow rate instead of raw register numbers.

## Also for PLCs, SCADA and remote sites
- [PLC Monitoring](https://logable.app/solutions/plc-monitoring): Connect PLCs to cloud dashboards via gateways.
- [SCADA Alternative](https://logable.app/solutions/scada-alternative): What your SCADA does not send you.
- [Remote Monitoring](https://logable.app/solutions/remote-monitoring): Sites without an operator on hand.
Setting up your first gateway? [monitoring for manufacturing](https://logable.app/industries/manufacturing) or read [how to connect a PLC or a Modbus device via a gateway](https://logable.app/docs/integrate/connect-plcs-and-modbus-via-a-gateway).

## Start with one gateway and one meter
Connect the first Modbus device today. The dashboard and the alerts are ready when it reports.