Record Modbus register and tag values to a local database and review them over time — trend charts, selectable time ranges, deadband and one-click CSV export. A built-in historian with no cloud and no separate server. Works with RTU and TCP devices on Windows 10/11.
No credit card for trial · Windows 10/11 · One-time license
A Modbus poll shows you the value now. A Modbus logger answers the questions that come later: what happened overnight, when did the value spike, is the trend drifting?
ModbusManager Pro records the values you choose to a local database, so you can scroll back through hours, days or weeks of real device data without standing up a full SCADA or historian system. Logging starts with a single click from any poll window or tag, and the data is stored on your own PC in a compact SQLite database — no cloud account, no subscription, no separate server to maintain.
Capture the signals that matter, keep the database lean, and get the data back out whenever you need it.
If you can poll a device, you can log it. No scripting required.
Most plant data still arrives over a two-wire RS-485 line rather than Ethernet. A serial Modbus logger has constraints an Ethernet one does not, and they decide how often you can realistically sample.
RS-485 is half duplex: one request and one reply at a time, in turn. Twenty meters on a shared line at 9600 baud cannot each be read every second. ModbusManager polls the whole line from a single register map and gives every window its own interval, so a slow energy meter and a fast drive can sit on the same bus without one starving the other.
A rough figure worth knowing before you set an interval: at 9600 baud one short read plus its reply takes roughly 30–60 ms including the silent gap between frames. Thirty reads per cycle therefore needs about two seconds, and asking for one second will simply build a backlog. At 115200 baud the same cycle is comfortable.
On a serial line one silent slave delays everything behind it, because the master waits out the timeout before moving on. The Serial Monitor shows the raw request and reply bytes, so you can tell a wiring fault from a wrong unit ID or a mismatched baud rate instead of guessing at it.
A commissioning job rarely stays on one transport. The same Modbus logger handles RTU on a COM port, ASCII, and TCP over Ethernet, and the history is stored the same way for all three — so a serial meter and an Ethernet PLC end up in one exportable record.
Serial lines have enough of their own arithmetic to deserve a page of it: covers frame timing at each baud rate, realistic intervals for a full device list, and how to tell a wiring fault from a wrong unit ID.
Commissioning and fault-finding — capture a device’s behaviour over a shift and review exactly what happened. Long-term monitoring — track temperatures, pressures, energy or flow and spot slow drift. Acceptance testing — record values during a test run and export the evidence. Energy and process studies — log consumption or production figures and analyse them in a spreadsheet. Anywhere you would otherwise reach for a separate data-logging tool, the built-in Historian keeps it in one application.
Both editions include the full Modbus master and slave toolset. Pro adds the Historian, Dashboard HMI and alarms on top.
| Feature | Standard — $49 | Pro — $119 |
|---|---|---|
| Modbus RTU, TCP & ASCII master | ✓ | ✓ |
| Built-in Slave Mode & register simulation | ✓ | ✓ |
| Charts, scaling, workspaces, 11-language UI | ✓ | ✓ |
| Data logging Historian | ✗ | ✓ |
| Trend charts with selectable time ranges | ✗ | ✓ |
| Per-series deadband | ✗ | ✓ |
| CSV export | ✗ | ✓ |
| Dashboard HMI & alarm system | ✗ | ✓ |
| Price (one-time, perpetual) | $49 | $119 |
A data logger is only useful if you can trust the time column six months later. Here is what gets written and what to decide before you start a long run.
| Decision | Why it matters later |
|---|---|
| Logging interval | Each poll window keeps its own interval. Sample fast enough to see the event you care about, and no faster — a one-second interval on thirty registers is roughly 2.6 million rows a month per register. |
| Deadband | Write a row only when the value moves by more than a set amount. On a steady process this is the difference between a database that stays small and one that fills a disk with identical readings. |
| Timestamp source | The time recorded is the PC clock at the moment the reply arrived, not a clock inside the device. On a long unattended run, make sure the logging PC has time sync enabled, or the record will drift away from every other system you compare it against. |
| Gaps | A missing row is information. If a device went silent or the cable was pulled, the history shows the gap rather than repeating the last known value — so an outage does not read as a flat, healthy signal. |
| Getting data out | History is kept in a local SQLite file on your own machine — no cloud account, no server to run. Pick a time range and export to CSV for Excel, a report, or a handover pack. |
Each of these has enough detail to deserve its own page, and each one is where a logging run usually goes wrong.
What one read costs at each baud rate, why twenty devices at 9600 baud cannot be sampled every second, and how to tell a wiring fault from a wrong unit ID.
Rows per day at each interval, sensible deadbands per signal type, and the one thing a deadband hides about a connection that has died.
Why a comma-separated file opens as one column in Europe, which values Excel mangles on import, and when to export wide instead of long.
Logging becomes simpler when the values you want already sit in one place. The gateway can collect registers from every device — RTU and TCP together — into one common register map, with engineering units applied. The Historian then logs a tidy, consistent address range instead of chasing scattered devices and mismatched data types.
Modbus gateway software →Download ModbusManager Pro and try the Historian, trend charts and CSV export on your own devices. No credit card, no cloud, no subscription.
Windows 10/11 · 14-day trial · Pro from $119 one-time
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