@fa_yoshinobu/node-red-contrib-plc-comm-kvhostlink 4.2.0

Node-RED nodes for KEYENCE KV Host Link communication over TCP/UDP.

npm install @fa_yoshinobu/node-red-contrib-plc-comm-kvhostlink

Node-RED KEYENCE KV Host Link Nodes

Node-RED nodes for KEYENCE KV PLC communication via Host Link.

PLC Comm Family

This library is part of the plc-comm family. See the package matrix for protocol, language, registry, and install-command mapping.

Supported PLC profiles

The maintained profile table is in PLC profiles. Choose one exact canonical PLC profile from that table.

Supported device types

The shared device and range tables are in the KV Host Link Device Ranges page. Use that page for supported device families, address syntax, and profile-specific notes.

Installation

@fa_yoshinobu/node-red-contrib-plc-comm-kvhostlink

In Node-RED, open Manage palette, choose Install, and search for:

@fa_yoshinobu/node-red-contrib-plc-comm-kvhostlink

Install the package, then restart Node-RED if your runtime asks you to.

Quick start

1. Open the Node-RED import menu.
2. Import examples/flows/kvhostlink-basic-read-write.json.
3. Open the kvhostlink-connection config node.
4. Set Host to 192.168.250.100.
5. Set Port to 8501.
6. Set PLC Profile to the exact canonical profile for your PLC, such as keyence:kv-5000.
7. Deploy the flow.
8. Trigger Read DM100:U and check the debug sidebar.
9. On a controlled test PLC/address only, optionally trigger Test DM100:U (random + restore).
10. The write path first saves the original value, writes a random different unsigned value, restores the original, and reads again. Restoration is best effort and can be interrupted by a transport or PLC failure.

Address and integer input is strict. Each high-level address must match one complete supported form; extra selectors or trailing text and incompatible BIT, F, or COMMENT selectors fail before connection or transport. Direct client integer arguments must be safe JavaScript integers. Configuration-node port and timeout text is converted explicitly at the Node-RED boundary. Connections are IPv4-only. The ordinary client serializes admitted operations in strict FIFO order, uses one absolute active transaction deadline, and never automatically reconnects or retries. Direct-bit writes require JavaScript Booleans. The library's explicit Boolean-only writeBitInWord API performs a two-request, non-PLC-atomic word update; it is never selected implicitly by a Node-RED named write. writeBitInExpansionUnitBuffer applies the same explicit contract to one .U word on an immutable expansion-unit URD/UWR route.

Float32 selectors require ordinary one-word device families; native 32-bit Z devices reject :F before FIFO admission or transport. Semantic .H reads return exactly four uppercase hexadecimal digits. Raw responses and hexadecimal write framing are not normalized by that read contract.

RDC device comments are byte payloads until the caller makes an explicit choice. For decoded text, select exactly utf8 or cp932; cp932 means Windows-31J compatibility commonly described by KEYENCE as Shift_JIS. There is no automatic/profile codec and no separate strict Shift_JIS alias. When the stored encoding is unknown, select raw Buffer output. Malformed text bytes fail strictly without fallback or replacement characters.

Malformed response bytes, an unknown operating-mode response, and stale or extra TCP response lines invalidate the TCP connection that produced them. UDP keeps the explicit logical connection and reuses a successful socket, resolved IPv4 address, and local endpoint across requests. Timeout, cancellation, malformed or additional response data, an unowned datagram, and socket failure close that physical socket; the next request creates a replacement without repeating DNS resolution. A failed request is never retried or replayed automatically.

Documentation

For a zero-code connectivity check, see PLC Scope (Windows).

License and registry

Commercial support

If you plan to embed this library in a paid or commercial product, please consider a separate support agreement or supporting the project as a sponsor.

Contact: https://fa-labo.com/contact.html