node-red-contrib-s7-rust 1.0.0

Siemens S7 nodes for Node-RED: S7comm and S7CommPlus (S7-1200/1500 symbolic access) clients written in Rust, running in-process (Node-API). Linux x64.

npm install node-red-contrib-s7-rust

node-red-contrib-s7-rust

Siemens S7 nodes for Node-RED. The two S7 protocols are written in Rust and run inside the Node-RED process as a Node-API addon:

• S7comm (classic, ISO-on-TCP port 102): S7-200, S7-300, S7-400, S7-1200, S7-1500, LOGO! 8. Absolute addresses, Siemens and nodes7 syntax.
• S7CommPlus (S7-1200/1500): symbolic access to optimized DBs and PLC tags ("DB_Data".speed, Motor_On), absolute I/Q/M/DB addresses, optional TLS 1.3 and password.

There is no external process, no compiler at install time and no runtime npm dependency. The package ships prebuilt binaries for Linux x64 (glibc and musl/Alpine).

This is the next generation of @oriolrius/node-red-contrib-s7. See Migration.

Contents

• Requirements
• Install
• Nodes
• Protocol coverage
• Prepare the PLC
• Addresses
• Values
• Examples
• Safety
• Performance
• Limits
• Migration from @oriolrius/node-red-contrib-s7
• Build from source
• License

Requirements

Windows, macOS and ARM are not supported. npm refuses to install the package on them (os and cpu fields).

Install

In the Node-RED editor: Menu → Manage palette → Install, search node-red-contrib-s7-rust.

Or on the command line, in your Node-RED user directory (usually ~/.node-red):

npm install node-red-contrib-s7-rust

Then restart Node-RED. The nodes are in the network category of the palette.

Nodes

Every node has full help in the editor sidebar. Bad tags never stop the other tags: they give null and an entry in msg.s7.errors, or msg.quality = "bad" in a watch.

The endpoint also adds two admin API routes for tools and the editor (Node-RED admin authentication applies, permission s7rs-endpoint.read):

• GET /s7rs/status/:endpointId: connection state, request count, errors, latency percentiles.
• GET /s7rs/call/:endpointId/:action: a read-only s7 info action (for example browse).

Protocol coverage

This map shows each protocol function and where it is available. It is strict: a function has ✅ only when a node uses it. The Rust tests run every ✅ and 🔒 function against the fake PLCs.

S7comm (crate s7)

S7CommPlus (crate s7plus)

Prepare the PLC

S7comm on S7-1200/1500

1. In TIA Portal, CPU properties → Protection & Security: enable Permit access with PUT/GET communication from remote partner.
2. In each DB you read: Attributes → clear Optimized block access. S7comm uses absolute addresses (DB1.DBW2).
3. Rack 0, slot 1 (the defaults for these families).

S7comm on S7-300/400: rack 0, slot 2 (default). LOGO! 8: select LOGO! 8 or LOGO! 8 (TSAP) and set up a server connection in LOGO!Soft Comfort.

S7CommPlus (S7-1200/1500): no PUT/GET, optimized DBs are fine. Use symbols. If the CPU has an access level password, set it in the endpoint. TLS needs S7-1500 FW ≥ 2.9 or S7-1200 FW ≥ 4.5.

Addresses

One address per line in the node, or in msg.tags / msg.topic.

Siemens syntax (S7comm and S7CommPlus)

DB1.DBX0.3  DB1.DBB0  DB1.DBW2  DB1.DBD4      also DB1.X0.3, DB1.B0, DB1.W2, DB1.D4
M0.0 MB0 MW0 MD0    I0.0 IB0 IW0 ID0 (E = I)   Q0.0 QB0 QW0 QD0 (A = Q)
PIB0 PIW0 PQW0 (peripheral)   T0   C0 (Z = C)
V10.3 VB10 VW20 VD30          LOGO! 8 / S7-200 V memory (= DB1)

Optional suffixes: [n] for an array of n elements, and :type:

Examples: DB1.DBW2:int, MD12:real, MW120[4], DB1.DBB10:string[20], DB2.DBB0:dtl. Without a type, the size gives one: X bool, B byte, W word, D dword.

nodes7 syntax (S7comm and S7CommPlus): DB1,REAL4, DB5,X0.1, DB2,S7.10, MI14, MR38, DB1,INT0.5 (5 INTs). Types with an R prefix (RWORD, RDI) are little-endian.

Symbols (S7CommPlus only): "DB_Data".speed, "DB_Data".values[2], "DB_Data".mat[1,2], "DB_Data".st.x, PLC tag names (Motor_On), or any name with the sym: prefix. Use s7 info → browse to list all symbols. Symbols and absolute addresses mix in one request.

Values

For writes, the node also accepts Date, BigInt, Buffer (for byte arrays) and numeric strings.

Examples

Import them in the editor: Menu → Import → Examples → node-red-contrib-s7-rust.

All examples use the address 192.168.0.1. Change it in the endpoint.

Safety

• The nodes cannot stop or start the CPU and cannot upload blocks. The Rust crates have these functions, but the addon does not expose them.
• setClock and syncClock change the PLC clock. The admin API refuses them.
• s7 write writes to the PLC at once. Test on a simulator (for example PLCSIM Advanced) before you write to a machine.

Performance

The protocol work (frame building, request optimization, value decoding, change detection) is in Rust. Node-RED gets ready-made JavaScript values, and a watch sends nothing when nothing changed. Reads of tags that are near each other go in one request ("gap" setting).

Measured in-process against the fake CPU of the test suite (p50, Linux x64):

On a real network the PLC response time is the limit (for example ~2 ms per S7comm read on an S7-1200 on the same LAN).

Limits

• The addon runs in the Node-RED process. A fatal error in native code stops Node-RED. The code is safe Rust; the Node-API layer is the only FFI.
• S7CommPlus watch uses polling, not PLC subscriptions.
• S7CommPlus: the PLC certificate is not verified (TLS protects against passive capture only).

Migration from @oriolrius/node-red-contrib-s7

The two packages can be installed together: the node types are different.

Addresses in nodes7 syntax (DB1,REAL4) work without change.

Build from source

You need Rust (stable), Node.js ≥ 18 and, for the release binaries, cargo-zigbuild (pip install cargo-zigbuild, or uv; the script uses uvx when it is not on PATH).

npm install                 # dev dependencies (Node-RED and the test helper)
npm run build               # addon for this host -> bin/linux-x64-<gnu|musl>/s7napi.node
npm test                    # Rust unit tests + Node-RED tests against fake PLCs
npm run build:release       # both published binaries (glibc 2.28 and musl)
npm run lint                # rustfmt + clippy
npm run validate            # node-red-dev scorecard checks

Repository layout:

crates/s7        S7comm client (Rust)
crates/s7plus    S7CommPlus client (Rust)
crates/s7napi    Node-API addon
lib/             JavaScript bridge to the addon, shared helpers
nodes/           Node-RED nodes (.js runtime, .html editor), locales/ (labels, help), icons/
examples/        example flows for the Node-RED import menu
test/            Node-RED tests (node-red-node-test-helper)
scripts/         build and packaging checks
docs/            release process

S7RS_NAPI=/path/to/s7napi.node makes the nodes load another addon build.

License

GNU Lesser General Public License v3.0 only (LGPL-3.0-only). The LGPL adds permissions to the GNU GPL v3.0. See NOTICE.

You can use the package in closed-source flows and applications. If you distribute a changed version of the Rust crates or of the addon, you must publish the source code of the changes under the same license.

Siemens, SIMATIC, S7-1200, S7-1500, LOGO! and TIA Portal are trademarks of Siemens AG. This project is not affiliated with or endorsed by Siemens AG.