Fuji MONITOUCH V9 — Communication Error

Fuji Electric · intermediate · 20 min

A Fuji MONITOUCH V9/V10 panel throwing a communication error usually has mismatched comm settings, an out-of-range PLC address on the active screen, or noise on the line. Learn to match the settings, monitor the $Pn status memory, and set Comm. Error Handling.

ℹ️ On a Fuji MONITOUCH V9/V10, a communication error is nearly always mismatched comm settings, an illegal/out-of-range PLC address on the screen showing the error, or line noise. The panel stores per-station comm status in $Pn memory you can put on screen to watch.

First: match the comm settings

On a Fuji Electric MONITOUCH V9/V10 panel (configured in V-SFT), the first check for any communication error is the obvious one: the communication settings of the V/TS unit must match those of the connected PLC/device, and the cable connection must be sound. Because serial links are noise-sensitive, data can be disrupted by noise — provide proper noise protection (screened cable, grounding, separation from power) on marginal installations.

The out-of-range address trap

A very common, non-obvious cause: a PLC device-memory address specified on the screen where the error occurs may itself be the cause. If a screen references a PLC address that is out of range or illegal for that PLC, the read fails and the panel reports a communication error that seems to come and go with the screen. Check the addresses used on the offending screen against what actually exists in the PLC.

Watch comms with $Pn system memory

MONITOUCH stores the communication result with each station in system device memory. You can monitor it live:

• System device memory $Pn: 100 – 355 (where n = PLC1 – 8) holds the comm status.
• Assign those addresses to numerical data display parts on a maintenance screen to see, per station, whether comms are healthy — invaluable when only one of several connected PLCs is failing.

Control what happens on error: Comm. Error Handling

In V-SFT you decide how the panel reacts to a comms fault. Under [System Setting] → [Hardware Setting] → [PLC n] → [PLC n Properties], set [Comm. Error Handling] — e.g. [Stop] to halt on error. Choosing the right behaviour keeps a single flaky station from taking down the whole screen unexpectedly.

Step-by-step

1. Match comm settings (baud/parity/stop/station/protocol) between the V9 and the PLC; check the cable.
2. Suspect the screen's addresses — verify no out-of-range/illegal PLC address is referenced on the error screen.
3. Add a $Pn monitor (100–355 for PLC1–8) to a maintenance screen to see which station is failing.
4. Set Comm. Error Handling in V-SFT (PLC n Properties) to the behaviour you want (e.g. Stop).
5. Address noise on the physical link if errors are intermittent.

Never do this

Don't just set Comm. Error Handling so the panel ignores the fault and keeps showing the last values — that puts stale PLC data in front of the operator. Find the real cause (settings, address, or noise) and restore a live, correct read.