cantarire-etichetare/vendor/syncpulse-scale-bridge/README.md

SyncPulse Scale Bridge

Plug an RS-232 weighing scale into any Windows PC, run one file, and it finds the port, the speed and the protocol by itself — then shows the live weight and serves it to your network as JSON.

English · فارسی

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Built by Farshad Zamani at Cloudtart. Free software that works with any system — an ERP, a MES, a web form, a spreadsheet macro or your own script — through a small HTTP/JSON interface.

Why

Most industrial scales and weighing indicators still talk over a serial port, and every brand uses its own format, speed and framing. Connecting one usually means finding the manual, guessing 9600 8N1 or 2400 7E1, writing a parser, and keeping a program running on the PC beside the scale. This project does all of that:

• Finds the scale by itself — listens on every COM port at every common speed, recognises 7-bit/parity framing, then asks the scale in the languages of the major manufacturers. Only read-only requests are sent: it never zeroes, tares or prints.
• Reads many formats — Mettler Toledo MT-SICS and Toledo Continuous, A&D, SMA (Rice Lake, Avery Weigh-Tronix, Cardinal, Fairbanks…), NCI, Ohaus, Sartorius SBI, CAS, the Chinese XK3190 family, Mahak MDS, any readable text, and custom binary/text formats you describe.
• Shows and serves the weight — a bilingual (English/Persian) page on the PC, and a JSON API with value, unit, stability, net/gross, overload and a checksum check, for any system on the network.
• One file, nothing to install — SyncPulseScaleBridge.exe. Copy it next to the scale and run it.
• Production-ready — survives unplugged USB cables and busy ports, opens the Windows Firewall port and starts with Windows from a button (UAC prompt), keeps an access key, and logs to a rotating file.

Quick start (Windows)

1. Download SyncPulseScaleBridge.exe from the latest release and copy it to the PC the scale is connected to — preferably into its own folder, e.g. C:\ScaleBridge\ (its settings file bridge.json and log are kept beside it).
2. Connect the scale's RS-232 port (directly, or through a USB-serial adapter) and switch the indicator's serial output on.
3. Double-click the program. A console window opens (keep it open) and the control page opens in the browser at http://127.0.0.1:8765/.
4. Find my scale → Start search. When the scale is found, give it a name (e.g. packing-1) and Save. The Scales tab now shows its live weight.
5. Network access: note the address and the access key, press Open port 8765 in the firewall and, if the bridge should run without anyone logged in, Start with Windows.
6. From any other machine: GET http://<address>:8765/weight?profile=<name> with the header X-Bridge-Token: <access key> — see the HTTP API.

No hardware at hand? Try it with simulated scales:

SyncPulseScaleBridge.exe --simulate mahak_mds,toledo_cont:4800:7E1,mt_sics

How auto-detection works

For each selected port:

1. Listen at 9600, 2400, 4800, 19200, 1200, 38400, 57600 and 115200 baud (8N1). A scale that sends by itself appears here. If the bytes are only readable once their top bit is cleared, the line uses 7 data bits with parity, and the port is listened to again as 7E1/7O1. What arrives is matched against every continuous format; framed formats with checksums win over loose text.
2. Ask — if nothing useful was heard, every read-only request in the library is sent at each speed and framing (quick: 8 combinations; thorough: 14) and the reply is checked by the protocol that was asked. A reply is confirmed by asking a second time.

Each result has a confidence score, the exact line settings, the request, a sample of the raw data and the current reading. A port that sent readable data in an unknown format is reported with that sample, so it can be configured by hand on the Manual & monitor tab.

Auto-detection reserves the ports it searches; reads of those ports answer 409 busy until it finishes.

Scales that send only when Print is pressed

Many indicators — especially those wired to a label printer — stay silent until the operator presses Print, then send the whole label. Tick The scale sends only when Print is pressed (and, if you like, Listen only) and press Print when the page asks: the port is held open at one speed until data arrives; unreadable data means another speed, and the next press is awaited at the next one. One press is enough for 7E1/7O1.

For such a scale the bridge keeps the port open all the time and records every label: weight, unit and the other values on the label (order number, shift, date …) in labels/<profile>-YYYY-MM-DD.jsonl beside bridge.json, and the last 500 through GET /labels. To keep the label printer working, connect the PC with a Y cable: scale TX (and ground) to both the printer and the PC's RX; the PC never transmits on that line.

Supported formats

ID	Format	Talks	Used by (examples)
mt_sics	Mettler Toledo MT-SICS (SI)	on request	Mettler Toledo terminals and balances
toledo_cont	Toledo Continuous (STX + status words, checksum)	continuous	Mettler Toledo IND/Panther/Jaguar/Lynx and many compatible indicators
and_std	A&D standard (ST/US/OL, Q)	on request / continuous	A&D and many Asian indicators
sma	SMA SCP-0499 (<LF>W<CR>)	on request	Rice Lake, Avery Weigh-Tronix, Cardinal, Fairbanks…
nci	NCI 3835 (W<CR>)	on request	NCI / Weigh-Tronix shipping scales
ohaus	Ohaus (IP)	on request	Ohaus Defender, Ranger, Valor…
sartorius	Sartorius SBI (ESC P)	on request	Sartorius balances, Combics/Signum
cas_enq	CAS ENQ/ACK/DC1 (experimental)	handshake	CAS and compatibles
xk3190_tf0	XK3190 continuous (tF=0, XOR checksum)	continuous	Yaohua XK3190-A9/A12 and compatibles
xk3190_reversed	XK3190 = reversed-digit stream — tested on real hardware (YH-T7E)	continuous	Yaohua XK3190 series, YH-T7E, big displays
mahak_mds	Mahak MDS binary (4D 09 04 07) — tested on real hardware	on request	Mahak MDS 13000 and related models
label_print	Label printer stream: TSPL / EPL2 / ZPL — tested on real hardware	on Print key	indicators wired to a TSC, Zebra or Argox label printer (e.g. PTC400)
ascii_generic	Any readable line with a number and a unit	continuous	everything else that streams text
custom_binary	A binary frame you describe (pattern, offset, length, byte order)	either	—
custom_ascii	A text format you describe (regular expression)	either	—

The formats follow the manufacturers' published documents and are covered by tests with their sample frames; mahak_mds was verified on a working scale. Brand names only describe data formats — many other indicators copy these formats. Requests that change the scale (zero, tare, reset, print, display off) are never sent.

Missing your scale? Open the Manual & monitor tab, look at what arrives, and save a custom profile — or open an issue with the model and a sample of the raw data. See CONTRIBUTING.md for adding a protocol.

HTTP API

Everything below needs the header X-Bridge-Token: <access key> except /health.

Request	Answer
GET /health	{ok, service, product, version, host, simulate, author, website, repository, capabilities}
GET /ports	the COM ports of the PC (name, description, USB IDs, chip, warnings)
GET /profiles	the saved scale profiles
GET /weight?profile=packing-1	the current weight of a saved profile
GET /labels?profile=label-1&after=SEQ&limit=100	labels printed by a print-only scale, oldest first (seq grows by one per label)
GET /weight?port=COM7&protocol=mt_sics&baud=9600&framing=8N1	the current weight without a profile
POST /weight {"profile": "packing-1"} or a whole profile	same, as JSON
POST /read {serial, exchange, frames, max_age_ms, wait_ms}	the raw frames, for systems that parse them themselves

Optional on /weight: max_age_ms (default 1500 — older readings are stale) and wait_ms (default 2500 — how long to wait for a fresh reading when the port has just been opened).

$ curl -H "X-Bridge-Token: $KEY" "http://192.168.1.20:8765/weight?profile=packing-1"
{"ok": true, "profile": "packing-1", "port": "COM7", "protocol": "mahak_mds", "open": true,
 "value": 550.0, "unit": "g", "stable": true, "net": null, "overload": false, "age_ms": 84,
 "stale": false, "measured_at": "2026-10-01T10:15:02.415+03:30", "raw_hex": "58 51 07 07 00 02 26",
 "checksum_ok": null}

import requests
r = requests.get("http://192.168.1.20:8765/weight", params={"profile": "packing-1"},
                 headers={"X-Bridge-Token": KEY}, timeout=5).json()
if r["ok"] and r["stable"] and not r["stale"]:
    print(r["value"], r["unit"])

stable comes from the scale when its format says so; otherwise it means the last N readings were equal (stable_samples, default 3). Errors answer with "ok": false and an "error" text — 401 wrong key, 403 client not allowed, 404 unknown profile, 409 port busy, 400 invalid request.

Security

• Access key — created on first start and kept in bridge.json; compared in constant time. Make a new one on the Connect tab at any time.
• Allowed clients — optionally accept only your server's address(es); the firewall rule can be limited to one address too.
• The control page is local only — it opens only on the PC itself (127.0.0.1). Its API also requires a custom header and a local Host, which protects it from other web pages and DNS rebinding. Other machines get a short information page instead.
• Read-only towards the scale — detection and reading never send zero, tare, print or configuration commands.
• Keep the bridge on a trusted local network; it speaks plain HTTP.

Firewall and running in the background

Windows Firewall blocks incoming connections by default, so other machines cannot reach port 8765 until a rule allows it. Open port 8765 in the firewall asks for administrator permission and runs:

netsh advfirewall firewall add rule name="SyncPulse Scale Bridge" dir=in action=allow protocol=TCP localport=8765 profile=any

It also removes block rules Windows may have created for the program when its Allow access? question was cancelled (a block rule beats any allow rule).

Start with Windows registers the scheduled task SyncPulse Scale Bridge: runs as SYSTEM at boot (before anyone logs in), never stopped after 72 hours, restarted every minute if it fails. Opening the program while the background copy runs simply opens its page.

The same from the command line:

SyncPulseScaleBridge.exe firewall [--remote-ip 192.168.1.10] [--remove]
SyncPulseScaleBridge.exe autostart [--disable]

Command line

SyncPulseScaleBridge.exe                       run the bridge and open its page (default)
SyncPulseScaleBridge.exe ports                 list COM ports
SyncPulseScaleBridge.exe detect [--port COM7] [--thorough] [--wait-print 60] [--listen-only] [--save NAME] [--json]
SyncPulseScaleBridge.exe monitor --port COM7 --baud 9600 --framing 8N1 [--request "53 49 0D 0A"]
SyncPulseScaleBridge.exe weight --profile NAME | --port COM7 --protocol mt_sics
SyncPulseScaleBridge.exe token [--new]
SyncPulseScaleBridge.exe protocols | about | --version

Options: --config FILE  --simulate SPEC  --verbose  --listen-host  --listen-port  --no-browser  --service

Troubleshooting

• No COM port / "A device attached to the system is not functioning" — many cheap USB-serial adapters use clone CH340 or PL2303 chips that recent drivers refuse. For CH340 install driver 3.5.2019.1 (Microsoft Update Catalog); for PL2303 use an older Prolific driver; or use an FTDI-based adapter. The port list warns about these chips.
• Nothing found — switch the serial output on in the indicator's menu (often COM, rS, SEr, Serial, Continuous or On request); check the cable (many indicators need a null-modem/crossed cable, some a straight one — pins 2, 3 and 5 are enough); put something on the scale or press Print while searching; try the thorough search; watch the raw bytes on Manual & monitor.
• Garbage characters — wrong speed or framing; the monitor shows the bytes, detection finds the right ones.
• The server cannot connect — check the firewall rule, the IP address, and that both machines are on the same network; curl http://<ip>:8765/health from the server must answer.
• Antivirus warning — single-file programs built with PyInstaller are sometimes flagged by mistake. Compare the SHA-256 checksum published with the release, or build the program yourself from source.

Build from source

git clone https://github.com/farshad-zamani/syncpulse-scale-bridge
cd syncpulse-scale-bridge
scripts\build_exe.bat                 :: venv, tests, then dist\SyncPulseScaleBridge.exe

Or run it directly with Python 3.9+ on Windows or Linux:

pip install -r requirements.txt
python -m scale_bridge                # on Linux the ports are /dev/ttyUSB0, /dev/ttyS0 …
python -m pytest                      # the test suite (simulated scales, no hardware needed)

Related projects

Useful projects that solve parts of the problem — none of them combines automatic detection, a multi-brand protocol library, a network API and a control page:

• VbScalesReader — VB6 library reading CAS, Elicom, Dibal, Mettler and Delmac protocols.
• Weigh-Scale-To-PC — Windows Forms display for an Arduino-based scale.
• RS232C_Scale — Raspberry Pi reader that logs a scale's readings to CSV.
• 232key and similar free keyboard wedge tools — type the weight into the active window.

License

GPL-3.0-or-later with one additional term under section 7(b): the author attribution shown by the program — in its page footer, About page, about command and /health answer — must be kept in all copies and modified versions. See NOTICE.md.

Author

Farshad Zamani — Cloudtart · GitHub · LinkedIn

Originally developed for the SyncPulse platform. Copyright © 2026 Farshad Zamani — Cloudtart.