KV Host Link — KEYENCE KV over Ethernet
KV Host Link is the upper-level link protocol a KEYENCE KV series PLC speaks on its built-in Ethernet port or on a KV-XLE02 communication unit. It is an ASCII command protocol, which keeps round-trip times short: in the published benchmark it was the fastest of the four protocols measured, at roughly 1.3–2.6 ms median round-trip.
| PLC families | KEYENCE KV-X500, KV-8000, KV-7000, KV-5000 |
| Transport | Ethernet, TCP or UDP |
| Default port | 8501 |
| Configuration tool | KV Studio |
Pick your language
All four implementations use the same model: pick a connection option set, pick your PLC profile, then read or write a device by name.
| Language | Install | Start here |
|---|---|---|
| Python | pip install plc-comm-kv-hostlink |
Getting started |
| .NET | dotnet add package PlcComm.KvHostLink |
Getting started |
| Rust | cargo add plc-comm-kv-hostlink |
Getting started |
| Node-RED | @fa_yoshinobu/node-red-contrib-plc-comm-kvhostlink |
Getting started |
There is no C++ (Arduino/PlatformIO) implementation of KV Host Link. See Choosing a language for how the four compare by runtime environment and footprint.
Configure the PLC first
The setup guides cover the KV Studio parameter screens for each model.
| Connection | Models with a setup guide |
|---|---|
| Built-in Ethernet (CPU) | KV-X500, KV-8000, KV-7000, KV-5000 |
| Communication unit | KV-XLE02, for a CPU with no built-in Ethernet port |
→ KEYENCE KV Host Link PLC setup · Troubleshooting & Codes · Device ranges
PLC model profiles
Select a profile such as keyence:kv-x500 and the library applies the correct
address grammar and per-model device ranges. With a KV-XLE02, pass the profile
of the CPU behind the unit. The profile is always chosen explicitly — no
implementation infers it from the PLC.
→ KV Host Link profile reference · Profile parameters · Device ranges by profile
Before you write anything
A wrong write on a running machine is not undoable. Read Bit Write Safety before your first write, and confirm an address range is safe for the connected equipment.
To check a connection with no code at all, PLC Scope is a Windows tool built on these libraries — keep the first session read-only.