KV Host Link Protocol for Rust

Async Rust implementation of the KEYENCE KV Host Link protocol, aligned with plc-comm-hostlink-dotnet and the shared plc-comm-hostlink-cross-verify harness.

Scope

TCP and UDP Host Link transport
full low-level Host Link command surface from the .NET reference
queued high-level helper API for typed reads/writes, comment reads, named snapshots, and polling
hostlink_verify_client wrapper binary for cross-language verification

Installation

cargo add plc-comm-hostlink-rust

The package name is plc-comm-hostlink-rust and the library import path is plc_comm_hostlink.

Examples and the verification wrapper require --features cli.

Quick Start

use plc_comm_hostlink::{
    open_and_connect, read_named, read_typed, write_typed, HostLinkConnectionOptions,
};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = open_and_connect(HostLinkConnectionOptions::new("192.168.250.100")).await?;

    let dm0 = client.read_typed("DM0", "U").await?;
    client.write_typed("DM10", "U", dm0).await?;
    let comment = client.read_comments("DM20", true).await?;

    let snapshot = client
        .read_named(&["DM0", "DM1:S", "DM2:D", "DM4:F", "DM10.0", "DM20:COMMENT"])
        .await?;

    println!("{comment}");
    println!("{snapshot:?}");
    Ok(())
}

High-Level API

HostLinkConnectionOptions
open_and_connect
read_typed / write_typed
read_comments
device_range_catalog_for_model
write_bit_in_word
read_named
poll
read_words_single_request / read_dwords_single_request
read_words_chunked / read_dwords_chunked
write_words_single_request / write_dwords_single_request
write_words_chunked / write_dwords_chunked

Comment reads also accept XYM aliases such as D10, E20, F30, M100, L200, X100, and Y100.

Device-range catalogs are also available for UI use cases such as device monitors:

use plc_comm_hostlink::{
    device_range_catalog_for_model, KvDeviceRangeCategory,
};

let catalog = device_range_catalog_for_model("KV-8000")?;
let dm = catalog.entry("DM").unwrap();
assert_eq!(catalog.model, "KV-8000");
assert_eq!(dm.device, "DM");
assert_eq!(dm.category, KvDeviceRangeCategory::Word);
assert_eq!(dm.lower_bound, 0);
assert_eq!(dm.upper_bound, Some(65534));
assert_eq!(dm.point_count, Some(65535));
assert_eq!(dm.address_range.as_deref(), Some("DM00000-DM65534"));

The full static range specification is documented in docs/DEVICE_RANGES.md.

Verification

Run formatting, static analysis, and tests:

cargo fmt --all --check

cargo clippy --all-targets --all-features -- -D warnings

cargo test --all-targets --all-features

Run the shared cross-verify harness after building the Rust wrapper: