Dasberry Modbus

Modbus RTU monitoring,
on your laptop

A free desktop app for real-time Modbus RTU monitoring, logging, reporting, and data transmission. Getting started is 100x simpler than standing up a SCADA system. Plug in a USB-to-RS485 adapter and you are monitoring in minutes.

Get the App, FreeSee What It Does

Everything you need to watch a bus

Four things, done well, all running on the machine in front of you.

Real-Time Monitoring

A live dashboard of every register you read, updating as fast as your devices can answer. Color-coded status and alarm thresholds surface trouble the moment it shows up.

  • Live value cards, updated continuously
  • Per-register alarm thresholds
  • Color-coded status at a glance
Unit 1 · COM3
Polling
Boiler Temp
184.2°C
Flow Rate
42.6m³/h
Boiler Temp (1h)Live
Line Pressure
6.1bar
Header TempHIGH
213.8°C
Flow Rate (1h)
Pump Speed1,180
Tank Level
78%

Logging

Every reading is stored locally in a built-in database, so you get historical trends, charts, and a full event log going back as far as you care to keep them. No server to stand up.

  • Built-in local database
  • Historical trend charts
  • Event and alarm history
History · local database
15m1h24h7d
Boiler Temp
Flow Rate
Retained 90 days
00:0006:0012:0018:00now
Event log1,284 entries
Header Temp alarm HIGH213.8 °C12:04:11
Unit 1 reconnectedCOM311:58:02
Log interval changed5s → 1s11:40:37

Reporting

Pull any registers over any time range into a clean CSV file, with values, units, quality, and timestamps. Ready for a spreadsheet, a colleague, or the archive.

  • Export straight to CSV
  • Values, units, quality, and timestamps
  • Pick your registers and time range
Export to CSV
Range: Last 24h
Boiler Temp×Flow Rate×Line Pressure×+1 more
Timestamp
Register
Value
Unit
Quality
12:04:11
Boiler Temp
184.2
°C
Good
12:04:11
Flow Rate
42.6
m³/h
Good
12:04:10
Line Pressure
6.1
bar
Good
12:04:10
Header Temp
213.8
°C
Good
+ 1,240 more rows
.csv
unit1_export_2026-07-11.csv1,244 rows · 68 KB
Download

Transmission

Push your readings wherever they need to go. A historian, a database, a SCADA or BMS system, flat files, an API, or an MQTT broker, all driven by simple scripts you control.

  • Send to historians, databases, SCADA, and BMS
  • Write files or POST to any API
  • Script-driven pipelines you control
Pipelines
Streaming
Live readings
Unit 1 · 4 registersevery 1s
Historian
Database
SCADA
BMS
Files
REST API
MQTT

Finally, free Modbus software that just works

Every other option was either a full-blown SCADA platform or a bare register reader built for bench testing. We wanted the middle. Something production ready but simple, so we built it and made it free.

Not a toy

Real logging, alarms, and data pipelines. Not just a register-poke tool that forgets everything the moment you close it.

Not a monster

No SCADA server to license, no week-long commissioning, no consultant. Install it and go.

Production ready, still simple

A signed installer, a local database, and a modern interface, running on the laptop you already have.

Free, forever

No seats, no trial clock, no upsell waiting three screens in. Download it and keep it.

The universe needed this. So we built it.

Why is it free? No catch.

We built Dasberry Modbus because our IOThrifty customers needed a simple way to keep an eye on their equipment. It is free for everyone, with no seats to buy and nothing held back. If it saves you time and you want to return the favor, buy your hardware from IOThrifty. That is what keeps it going.

Shop IOThrifty Hardware

Start monitoring in minutes

A signed Windows installer and a USB-to-RS485 adapter are all you need. Free to download, free to keep.

Get the App, Free