On the reported CX5130, switching off the HMI was followed by a PLC with no screen image, no TwinCAT light, and no output signals; that sequence alone does not prove the HMI caused the failure. Check the supply path first, then determine whether the controller reaches BIOS and whether the CFast storage is the failing component.
Which part of the startup path is failing?
The observed path is: supply power reaches the controller, the controller starts its hardware and firmware, it may display BIOS, then it loads the operating system from CFast and starts the PLC runtime and project. The HMI is a separate endpoint unless its power-off also removed power from the controller or another device in the control system.
Separate the observations rather than treating “won’t boot” as one fault. “No screen image” is different from an operating system that fails to load; “no output signal” may result from the controller never starting, but it also requires checking the controller’s supply and the output circuit. The reported case did not establish which of those mechanisms caused the failure.
| Observation | What it narrows down | Next check |
|---|---|---|
| No screen image, including no BIOS image | Could be a supply, hardware, display-path, or controller-startup problem; it does not isolate CFast. | Measure controller supply voltages and check whether power-off affected other devices. |
| BIOS image appears, but the operating system does not start | The controller displays firmware output; boot storage or its contents become a stronger suspect. | Preserve the original CFast card, then assess a cloned or restored card. |
| Controller starts but PLC outputs remain absent | Startup may have progressed beyond BIOS, but output operation still needs separate verification. | Check runtime/project startup and the output circuit rather than assuming a storage fault. |
Did the controller lose its own supply when the HMI was switched off?
Before removing storage or ordering a replacement, confirm the physical power path. Determine whether the HMI switch also controls any other devices, as this can remove power from the controller or its supply. Measure VUS and VUP at the controller supply terminals; the troubleshooting question in this case was whether both were close to 24 VDC. Record the measured values and compare them with the applicable device documentation rather than treating an approximate reading as proof that the supply remains healthy under load.
- Identify the supply conductors and terminals for
VUSandVUPfrom the controller documentation and wiring diagram. - Measure both voltages with the controller powered, and record whether they remain stable during the attempted startup.
- Check whether the HMI-off action also de-energized the controller, its supply, or associated equipment.
- If either supply is missing or unstable, correct that power-path fault before evaluating CFast or replacing the controller.
A dark screen alone cannot distinguish a failed controller from missing supply or a display-path issue. If both supplies are present and the controller still produces no image, proceed to the BIOS-versus-no-BIOS decision without concluding that the storage card is responsible.
Does the CX5130 show a BIOS image?
Check the controller display during a controlled restart and note exactly what appears. The distinction matters: a visible BIOS image means the controller has produced firmware output, while a completely blank display leaves hardware, power, and display-path checks in scope. No BIOS image is not a reason to reflash CFast as the first response.
Confirm the model from the controller’s nameplate before applying model-specific service instructions. The case was described as a CX5130, but the initial identification was uncertain. Keep the symptom record specific: BIOS visible or absent, TwinCAT light state, supply measurements, and whether any output signals return. These observations help the service provider decide whether to inspect the controller or its boot media.
Should you replace or reimage the CFast card?
When BIOS is visible but the operating system does not start, a damaged or corrupted CFast image is one candidate. The reported recovery attempt was to remove the CFast card and clone the operating-system image to a new card. The case does not state the result of that attempt, so treat cloning as a diagnostic/recovery option, not a confirmed fix.
- Power down the controller before removing the CFast card.
- Make a complete image of the original card before changing its contents. Retain that image and the original media so you can return to the starting state.
- Use a known-good compatible replacement card and restore or clone the image to it; do not overwrite the only copy of the original.
- Install the replacement card and test startup. Record whether BIOS appears, whether the operating system loads, and whether the PLC runtime and project start.
If the replacement image produces the same blank-screen condition, return to the supply and hardware path rather than repeatedly rewriting storage. If BIOS remains visible but the operating system still fails, the card, image, or software restoration remains under investigation. Confirm card compatibility and imaging procedure with the equipment supplier or service provider; no card specification or flashing utility was identified for this installation.
When should you service or replace the controller?
If the controller has no display even after supply checks, storage replacement alone may not address the failure. The case’s troubleshooting path treated a blank display as grounds to contact the equipment service channel or evaluate controller replacement. Ask for a diagnostic before committing to replacement when repair is available, and provide the model, supply measurements, BIOS observation, and CFast test results.
Check the machine’s service arrangement before shipping the controller or buying hardware. In the reported installation, the controller manufacturer directed the owner to the company that supplied the machine because service was arranged through that company. Your service route may differ; confirm the responsible OEM, integrator, or authorized service provider for the specific machine.
Preserve software licensing as a separate replacement task. TwinCAT licensing was reported as transferable by contacting Beckhoff support, while the machine supplier’s service agreement affected who could handle the repair. Before replacing the unit, identify the installed TwinCAT and HMI software licenses, determine whether they are held on a license terminal or USB dongle, and ask the appropriate service provider how to transfer or restore them. Do not assume that a cloned operating-system card also carries a usable license or project configuration.
How do you verify the recovery?
Verify the whole startup chain, not just the screen. A successful boot should progress from stable measured controller supplies, through visible startup/operating-system activity, to the PLC runtime and project. Then confirm the outputs at the controller and at the connected field devices; a display returning does not prove the output path works.
- Record stable measured values for
VUSandVUPduring startup. - Confirm the BIOS image appears and note whether the operating system loads from the installed card.
- Confirm the TwinCAT light and runtime state return to the expected operating condition for the machine.
- Check project status, then test each affected output at the controller and verify the corresponding field device responds.
- Save the working CFast image and license/service details with the machine’s recovery records.
Frequently asked questions
How do I tell whether a CX5130 has a CFast problem?
First check whether BIOS appears. BIOS with an operating-system boot failure points toward the card or image; no image at all requires supply, display-path, and hardware checks before blaming CFast.
How do I check VUS and VUP on a CX5130?
Measure both at their documented supply terminals with the controller powered and record the values during startup. The case raised whether each was close to 24 VDC; confirm acceptable limits in the controller documentation.
How do I reflash or clone the CFast card?
Power down, remove the original card, and make a complete image before writing to another card. Restore or clone to a compatible replacement, then test the BIOS, operating-system boot, runtime, and project; confirm the card and imaging method with the service provider.
Can I move TwinCAT licenses to a replacement controller?
TwinCAT licenses were reported as transferable by contacting Beckhoff support. Check whether this installation uses a license terminal or USB dongle, and coordinate with the responsible OEM or integrator before replacement.
How do I verify the PLC is fixed after replacing CFast?
Confirm stable VUS and VUP, BIOS and operating-system startup, TwinCAT runtime/project status, and output response at both the controller and field device; record those final test results.