Keyence VT5 — No Communication to the PLC

Keyence · intermediate · 25 min

A Keyence VT5 that won't talk to the PLC almost always has the wrong driver for that specific PLC, a wiring/pinout mismatch, or mismatched comm settings. Use the per-device connection manual and check the wire mapping.

ℹ️ The VT5 supports many PLC brands, but each one has its own driver and wiring. 'No response' is nearly always the wrong driver or a wire-mapping mistake — Keyence publishes a connection manual per device for exactly this.

Confirm the PLC is supported and pick the right driver

The Keyence VT5 (and VT3) touch panel can connect to PLCs from many manufacturers, but you must check the connectable PLCs for your specific HMI and choose the matching driver. Keyence provides PLC connection manuals grouped by device — find the one for your exact PLC model and follow its settings. Using a near-but-not-exact driver/protocol is a common cause of no communication.

Wire mapping is the #1 practical cause

For serial connections, proper mapping of the wires between the HMI side and the PLC side is critical — a swapped or wrong pin is the most common real-world reason a VT5 won't communicate. The per-device connection manual gives the exact pin-to-pin wiring for that PLC; follow it precisely (RD/SD, RS/CS, signal ground, and shield as specified). Confirm you're on the correct port (the VT5's serial vs. Ethernet port) for the driver you configured.

Match the communication settings

In VT STUDIO, confirm the driver's parameters match the PLC:

• Serial: baud rate, data bits, parity, stop bits, and the station/unit number must match the PLC exactly.
• Ethernet: the VT5 IP and the PLC IP must be on the same subnet, the PLC IP/port in the driver must match the real PLC, and there must be no IP conflict.

Step-by-step

1. Confirm the PLC is in the VT5's connectable list and select the correct driver in VT STUDIO.
2. Open the per-device connection manual for that exact PLC and follow its wiring and settings.
3. Serial: wire the cable pin-for-pin per the manual and match baud/parity/stop/station number.
4. Ethernet: match IP/subnet/port and confirm no conflict.
5. Re-transfer the VT5 project and test; consult the VT5 error-code list for any code shown on the panel.

Verify

With the correct driver, exact wiring, and matched parameters, the VT5 connects and tags update live. If it still won't communicate, re-check the wire mapping (serial) or IP/subnet/driver settings (Ethernet) against the connection manual — those are the details a quick look can miss.

Good practice

Keep the specific PLC connection manual with the machine documentation; the exact pinout and parameter set for that PLC is the single most useful reference when a VT5 link needs re-commissioning.