A frozen number, an unresponsive button and a dark operator panel require different investigations. Paper cup machine HMI and PLC communication troubleshooting starts by identifying which information or function has stopped, rather than treating every panel symptom as a lost network connection.
Keep the first alarm and operating context before an authorized reset. Use this guide to prepare a fault report for the installed control system; addresses, software changes and recovery actions require the actual machine documentation and qualified automation personnel.
Separate the display from the data connection
Record whether the panel is dark, still starting its application, responsive locally, or displaying a named communication alarm. A locally responsive page shows that part of the panel application is working. It does not prove that the values on that page are current controller data.
Identify the affected scope. Are all controller values stale, only one connected device unavailable, or just one number unchanged? Record the screen name, tag description where available, displayed unit and the time of observation. For example, if a cup counter updates while a displayed heater value stays fixed, establish whether those values come from the same device before assigning a common connection fault. A stable process value may correctly remain unchanged; choose a documented reference that is expected to update during the permitted operating state.
| Observed scope | Evidence for the specialist | Conclusion to avoid |
|---|---|---|
| Panel dark or unable to start its application | Panel identity, startup behavior and authorized power/status checks | A network cable must be faulty |
| All values from one controller stop updating | Named connection, exact alarm, controller mode and available connection diagnostics | A responsive panel proves communication is healthy |
| One value remains unchanged while related data updates | Tag reference, data-quality indication if supported, project revision and expected process change | The whole network has failed |
| Values update but a command is rejected | User access, machine mode, displayed inhibit and command/event record | The command must have reached the controller |
These branches organize the investigation. They are not diagnoses or instructions to force a value, trigger motion or disconnect equipment.
Establish a common event timeline
Capture the alarm text, affected connection or device, last successful operation and recent changes. Note each record's source: panel alarm history, controller diagnostic buffer, drive message or operator observation. If device clocks disagree, record that discrepancy; sorting uncorrected timestamps can produce a false first-event sequence.
An indicator marked RUN, a network link light and a successful exchange of the required application data are different observations. Ask the specialist to explain which evidence establishes each layer. Preserve logs before restarting where the approved procedure permits; a restart that clears the symptom does not identify its cause.
Ask for diagnostics for the installed system
Use the technical documentation checklist to identify the panel, controller, communication interface and approved project revisions. Do not assume the connection is Ethernet or that every machine uses the same address scheme.
Siemens' WinCC documentation distinguishes device status from connection information, including the configured communication partners and interface. That is an example of evidence available in the specified engineering environment, not proof that a HANNAI machine uses Siemens equipment or provides those screens.
For the actual system, request the equivalent supported diagnostic record. Physical access inside the cabinet, live measurements, address changes and software transfers belong to qualified personnel working under the supplied procedure. Keep the approved backup and replacement history available before any authorized change; a project from a similar machine is not a validated recovery file.
Verify data recovery and machine readiness separately
After authorized work, verify that the intended data updates from the intended controller and that the affected function behaves correctly under the approved test. Record what changed and what evidence improved. A repaired connection may reveal a legitimate process inhibit that was previously hidden by stale information.
Follow the sensor and interlock guide for the separate input-function question. Communication recovery does not validate protective functions. Never bridge a contact, force an input or issue a motion command merely to prove a screen is live.
Before production release, complete the applicable protective and process checks, confirm the approved project revision and inspect trial output where the interruption could affect cup quality. For configuration discussions, identify the exact paper cup machine rather than assuming a control architecture from its model name. Send HANNAI the fault record with device identities, alarms, event timing and the affected data or command.
Frequently asked questions
Does one frozen number prove a communication failure?
No. Compare its expected behavior, tag reference and supported quality information with other data on the same connection before assigning the fault.
Does a network link light prove that controller values are current?
No. It is physical-link evidence, not proof that the intended application data is being exchanged correctly.
Why can a button remain unavailable after communication returns?
The machine may still have a valid mode, access or sequence restriction. Identify that condition through the documented system instead of bypassing it.
Is a restart that restores the screen a completed repair?
Not by itself. Retain the original record, document the authorized action and verify the affected function under the agreed recovery conditions.