HMI protocol test fails while ping passes: recover firmware

Why does ping pass but the protocol test fail?

Ping and the protocol test sit at different layers. Ping checks that the panel's network stack reaches the destination address. The protocol test checks that the panel completes the application-level exchange with its controller. A pass and a fail together point at the panel's firmware or application.

Ping exercises ICMP echo between two IP stacks and nothing else. The protocol test exercises the exchange the application actually uses with the controller, with the protocol and port settings the project specifies. When the first passes and the second fails, the cable, the switch and the addressing have answered for themselves. The remaining suspect is the software on the panel. Stay within the usual copper Ethernet limit of 100 m per segment while you test, so path length never muddies the result. The same split shows up across industrial hardware: one documented controller case ended in a failed code upload while the ping kept passing.

What do the panel's self-test results tell you?

The panel's built-in Ethernet self-test gives you the split you need. Ping pass with protocol test fail places the fault in the panel's communication firmware or application. Ping fail sends you out to the cable, the switch port and the addressing first.

• Ping passes, protocol test fails. The panel's protocol exchange is broken. Work panel-side: controller target, application, firmware.
• Ping fails. The network path is the fault. Check the cable and connectors, the switch port, then the IP address, subnet mask and gateway. The same order applies when PROFINET ports go undetected after a ping.
• Both tests pass, the application still cannot read values. Re-check the configured controller target and its protocol settings in the project. A ping can pass against a device the application is not using.
• No failure message along the top of the display. Read the two test results as the verdict. The panel in the reported failure showed no banner there while its exchange was down.

Repeat both tests and write the results down, along with the panel model and firmware version. Those two records drive every later step.

Which checks come before you touch the panel's memory?

Before any reset, confirm the project still points at the controller installed. The configured target and protocol must match the PLC and its communication module. The link lights at both ends must be lit, and the project addresses must match the addresses on the devices.

Read the settings back from the panel and from the controller; guessed addresses produce a ping that passes against the wrong box. Keep the two channels separate in your head as well, because a programming link that dies while the controller link still works is a different diagnosis with its own fix. Where the wiring allows it, put the panel and the controller on a short, known-good path and retest. Change one thing per test, so the change that restores the exchange is also the change you can name.

How many application reloads and resets should you run?

Run one application download and stop there. Download the correct project once and rerun the protocol test. If it still fails while the controller target and the network path check out, stop cycling resets. The fault sits below the application, and firmware recovery is the next step.

Save the application and write down the panel settings before the first download, so every step stays reversible. Use the exact project built for the installed machine, and rerun the protocol test after each single change. In the reported failure, a memory reset plus reload changed nothing, and a factory default plus reload changed nothing either. Those results under a confirmed target and path are the diagnostic output, and a third attempt of the same kind adds no new information. Treat a factory default as a repair step with a cost: save first, and write down what to put back afterwards.

How does firmware recovery bring the panel back?

Firmware recovery rewrites the panel's operating software from the programming PC over a USB A-B cable. One re-send of the running version, 2.53 in the reported failure, restored the protocol exchange that three application-level steps could not.

1. Save the application from the panel and record the running firmware version. The field maintenance procedure for reading an HMI panel's firmware version shows where panels usually print it.
2. Get a USB A-B cable: the printer-style lead with a flat A plug for the PC and a B plug for the panel. Keep it under the 5 m USB limit so the PC can sit at the cabinet door.
3. Open the recovery tool that ships with the panel's programming software. On the PC it sits in that software's Start menu folder, under an entry for special tools or utilities.
4. Connect the cable, put the panel into recovery the way the tool instructs, and start the transfer.
5. Let the transfer run to the end. A power cut or an interrupted transfer in the middle of recovery is how a slow panel becomes a dead one.
6. Re-send the firmware version the panel was already running; 2.53 was the version that restored the reported panel.
7. Reload the saved application, put back the settings you wrote down, and rerun the self-test: ping passes and the protocol test passes.

Use only the recovery tool and the image that come from the panel maker or its distributor. If you have ever rebuilt a PC from a manufacturer's recovery USB stick, the pattern is identical. The maker supplies the tool, the tool matches the image to the machine, and the machine rewrites itself from that image. The HMI version simply aims the same process at the panel's firmware.

Example: the full recovery scenario

The reported case runs the whole decision path in order, and every figure in it is one you can put on a work order. A panel with a few months of service fails its protocol test while ping passes, over a copper run inside the 100 m segment limit. The fault survives 3 application-level steps, and 1 re-send of firmware version 2.53 over a 1.8 m USB A-B cable brings the exchange back.

The machine: an HMI panel exchanging data with a PLC over Ethernet through the PLC's Ethernet communication module, on a copper run well inside the 100 m segment limit, with no failure message showing along the top of the panel. The PC sits at the cabinet door on a 1.8 m USB A-B lead, inside the 5 m USB limit. The operator reports stale values on screen.

Three actions at the application and configuration layer produced zero recoveries; one action below them produced one. Every layer above the firmware had been tested under a confirmed target and a passing ping. The layer left standing was the firmware, and that is where the repair went.

Decision: with ping green, protocol red, and one clean application reload behind you, go straight to firmware recovery. The failed resets before it are what justify skipping a second and third attempt.

When can the panel go back on the machine?

Return the panel only after the panel-level test and the machine-level test both pass. The protocol test must pass, live controller values must update on screen, and one approved operator action must reach the controller and return the expected feedback.

Use the site's approved test conditions, and prove the exchange with a permitted, nonhazardous action whose feedback you can watch at both ends; never an output that can start a drive or move material. Watch the panel through a normal operating interval, then rerun the protocol test once more. Record the firmware version, the application revision and the recovery date in the equipment record. If the exchange drops again, capture the time, the test results and any message on the panel, then take the panel out of service. Resets without a new clue only erase the pattern the vendor needs to see.

Should you upgrade the firmware version while you are in there?

Separate the repair from the upgrade. The re-send of the running version, 2.53 in the reported failure, is the demonstrated fix. The jump to 2.71 was raised as a possible follow-up but was never shown to address this fault, so the two changes do not belong in one test.

Change one variable at a time. Recover with the running version first, prove the machine on live data, and only then plan the version upgrade as its own change, with its own test window and its own way back. Save the application, record the version, and keep the USB A-B cable and the 2.53 image where you can reach them if the upgrade misbehaves. A version change is also a moment when panels lose their communication settings, and what to check when a panel will not communicate after a firmware update covers that recovery path.

Recommendation: when ping passes and the protocol test fails, verify the controller target and the network path, and run one application reload. If the protocol test still fails, recover the panel's firmware with the programming software's own recovery tool over a USB A-B cable and re-send the firmware version the panel was already running. Return the panel to the machine only after the protocol test and a live-data check both pass, and treat any version upgrade as a separate change with its own test.

Questions