Companion tool · Free for FluviaPro customers
FluviaPro Splitter
Serial NMEA-to-TCP bridge, multi-client
Does your GPS / AIS unit only feed one piece of software at a time? The Splitter rebroadcasts the NMEA-0183 COM-port stream as a TCP server. Periskal, FluviaPro and any other software can finally read the same signal in parallel.
Origin story
Why we built it
During FluviaPro field tests aboard the AMETHYSTE with our pilot partner, one detail jumped out: Pascal had to choose between keeping Periskal open for his charts and opening FluviaPro for his logbook. The two couldn't read the AIS unit at the same time, simply because a COM port can only be opened by one process at a time under Windows.
All the off-the-shelf solutions existed: signed Microsoft virtual COM port drivers (expensive, per-seat licensing), home-grown kernel modules (fragile, require a reboot on crash), physical hardware splitters (an extra cable to route through the wheelhouse). None of them held up over time for a bargee who just wants Windows to boot and have everything work, full stop.
So we wrote FluviaPro Splitter over a weekend: a small user-space bridge that opens the COM in read-only mode, listens to the NMEA stream, and rebroadcasts the raw bytes on a local TCP server. Any software, Periskal, FluviaPro, an in-house client, connects to the TCP port instead of the COM port. No kernel driver to sign, no virtual port to maintain, no Electron window to leave open (the bridge runs as a Windows service).
Because it solves a universal problem of the modern wheelhouse and only makes sense around an NMEA unit, we decided to give it away for free to every FluviaPro customer. It's our way of thanking those who trust us during this pilot phase.
The problem in detail
One COM port = one piece of software at a time
Under Windows (and every Unix, actually), a physical serial port is an exclusive file: the first process to open it locks it. Until it is closed, no other software can read from it, not even a test program, not even PuTTY. This is a low-level guarantee that prevents simultaneous writes to the hardware.
In practice, on board: if Periskal starts at boot and keeps COM3 open, FluviaPro trying to open COM3 gets an 'access denied' error. You have to close Periskal, open FluviaPro, close FluviaPro, open Periskal. That doesn't fly day after day.
Traditional workarounds: (1) virtual COM port drivers, they work but are paid per seat and signed by a third-party vendor you have to trust; (2) home-grown kernel modules, banned on recent Windows without a Microsoft signature; (3) physical splitter boxes, expensive, bulky, one more cable in the wheelhouse. No clean option for a bargee who just wants things to work.
The solution
One stream, as many pieces of software as needed
The Splitter opens your COM port read-only, auto-detects the baud rate and NMEA stream, and rebroadcasts every byte on a TCP server. Your software connects via TCP instead of COM. Everything runs in user space, with no kernel driver and no virtual COM port.
Your GPS / AIS unit
Stays wired to its COM port like today. No hardware change.
The Splitter opens the COM
Read-only, auto baud-rate scan, NMEA-0183 frame detection.
N pieces of software read TCP
Periskal, FluviaPro, your in-house cartography, all read the same stream in parallel.
New · Splitter v2
The collegial radar for neighbours, free
With Splitter v2, your AIS transponder doesn't just push YOUR position: it also decodes in parallel ALL the VHF frames from boats within range (5-30 km on inland waters). Splitter quietly forwards these neighbours to the FluviaPro server, which rebroadcasts them in real time to your tablet. Zero database storage, zero trace, full GDPR compliance.
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On the voyage map
Each neighbour becomes a heading-oriented marker, colour-coded by category (cargo / tanker / passenger / hazardous goods / pleasure / fishing). On click: MMSI, ENI, name, dimensions, draught, destination, ETA, ADN cones, crew on board.
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"Nearby boats" tab
On the voyage record, a tab lists every captured neighbour, sorted by distance. For each one: distance to your boat, speed, heading, and the kinematic relation in plain language — "Approaching", "Crossing", "Moving away", "Parallel" — with CPA and time-to-closest-approach computed.
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Zero storage, zero cost
The bus lives in server RAM, purged every 5 minutes. Not a single byte in the database, not a log row, no photo. Included at no extra cost in every FluviaPro plan.
A simple UI, built for the wheelhouse
The UI lists detected ports, lets you pick the TCP broadcast port, and installs the Windows service in one click.
Features
Everything you need, nothing extra
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Automatic NMEA-0183 detection
The Splitter probes COM ports, identifies NMEA frames and ignores parasitic noise.
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Automatic baud-rate scan
Tries standard baud rates (4800, 9600, 38400, 115200) until it locks on. No manual setting.
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Multi-client TCP server
Each COM port is rebroadcast on a TCP port of your choice. As many parallel client connections as needed.
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Windows service, auto-start
Installed as a Windows service: starts at boot, runs in the background, no window to keep open.
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Automatic reconnection
If you unplug and replug the unit, the Splitter finds the port and republishes the stream with no intervention.
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Read-only by design
The Splitter never writes to your unit. No risk of corrupting your AIS or saturating the bus.
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No kernel driver
Everything in user space. No module to sign, no virtual COM port to maintain, no BSOD risk.
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Local config and logs
Config and logs stored under %ProgramData%\FluviaProSplitter\. Easy to inspect in case of trouble.
Compatibility
Compatible with your existing setup
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Operating system
Windows 10 and 11 · 64-bit
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Hardware
NMEA-0183 GPS and AIS units over serial / USB
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TCP clients
Periskal, FluviaPro and any standard TCP client
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Firewall
Rules added automatically at install time
Download
How do I get it?
FluviaPro Splitter is free for every FluviaPro customer. Get in touch, we'll send you the download link and the installation guide.
Request downloadHow about discovering FluviaPro?
The Splitter is a companion tool, but your fleet's true cockpit is FluviaPro. Voyages, locks, certificates, crew and logbook in a single app, built for inland navigation.