# ⚠️ Industrial use disclaimer This software talks to industrial control systems (PLCs, RTUs, drives, meters). A Modbus write can move physical equipment — valves, motors, heaters, pumps — and a wrong write can damage equipment, ruin a batch, or cause a safety incident. **Read this before deploying in production.** ## You are responsible for - **What your flows do.** Node-RED, this palette, and the bytes palette only carry your bytes — they don't know whether `setpoint=200` means 200 °C or 200 RPM, or whether opening valve 7 floods the building. - **Testing.** Always test against the embedded slave server (or a simulator like ModPackQT's own Modbus simulator) before pointing at a live device. - **Staging.** Have an air-gapped or read-only staging environment between development and production. Never deploy a flow change directly to a system controlling real assets. - **Backups.** Keep your Node-RED flows in version control. A flow recovery is faster than a hardware recovery. - **Compliance.** If your installation is subject to safety regulations (IEC 61508, ISO 13849, OSHA, FDA 21 CFR Part 11, etc.), this software is **not certified** for safety-instrumented systems (SIS). Use it for monitoring, supervisory control, and data acquisition — not for safety interlocks. ## Recommended safe-use workflow 1. **Always start with reads.** Get the values flowing in before you wire any write back out. 2. **Use the embedded slave server as a sandbox.** Wire your flows to write into the local slave first; verify the bytes are correct with `decode-…` nodes; only then point them at a real device. 3. **Add the `modpackqt-traffic` node** (free) to every config — it logs every read and write with timing, value, and error info. If something goes wrong, the trail is right there. 4. **Test the worst case in the bytes palette.** Round-trip your values through `encode-… → decode-…` to confirm the byte/word order matches the target device. Wrong endianness on a setpoint write is a common cause of damage. 5. **Wrap critical writes in a guard.** A `function` node that rejects values outside a safe range, or a `switch` node that blocks writes during maintenance windows, costs you 30 seconds and saves you a service call. 6. **Pin a major version in production** (`"node-red-contrib-modbus-modpackqt": "^2.0.0"`). We follow semver — patch and minor releases are backward compatible; major releases may not be. ## What this software does NOT promise - It is **not** safety-rated. - It is **not** suitable for safety-instrumented systems (SIS / SIL-rated loops). - It is **not** a substitute for a real PLC's hardwired interlocks. - It does **not** guarantee delivery, ordering, or completeness of writes beyond what the underlying `modbus-serial` library and the network/serial link provide. ## Reporting issues - **Bugs / unexpected behavior:** open an issue at (or the package's GitHub repo when listed). - **Security issues:** email **support@modpackqt.com** privately. Please follow responsible disclosure — give us 90 days to fix before publishing. - **Paid customers:** include your customer ID for priority response. ## Updates This package is distributed via npm. **Updates are never automatic.** Node-RED will show "update available" in the palette manager when a new version is published; you choose when to upgrade. We strongly recommend subscribing to release notifications: - **GitHub:** watch the repository (when listed in `package.json`) - **npm:** `npm view node-red-contrib-modbus-modpackqt versions` - **Email** (paid customers): security and breaking-change notices go to your registered address. ## Licence This software is provided under the MIT License — see `LICENSE`. The limitation of liability in the LICENSE applies to all users. See for the full terms. --- If any of the above is unacceptable for your project, **do not use this software in production**. There is no shame in that — Modbus is a mature protocol with many alternative implementations, including hardware-based gateways with safety certifications.