Yes: set the panel's built-in inactivity return to 10 minutes with the home screen as the destination. If the panel has no built-in timer, run a 600-second PLC timer on a touch-activity bit and write the home screen number to the panel's documented screen-change register. Verify with a 9-minute no-touch test and a touch-just-before-timeout test.
An operator opens a setup screen, gets pulled off the machine, and the next shift finds a menu full of values nobody should change by accident. The fix is standard panel behavior: after a fixed idle time the panel goes back to its home screen on its own. Many HMI projects do this with one documented setting. The rest do it with a timer in the PLC and a screen-number write across the panel link that already exists. This article gives you both routes, the definition of operator activity that keeps the timer honest, and the tests that tell a working return from one that fires early or never fires.
The short answer
Set the built-in inactivity return to 10 minutes, with the home screen as the destination and a reset on any touch. Open the panel project in its editing software and look through the panel settings, screen settings and navigation options for an entry named inactivity, idle, logout or screen saver that includes a return-to-screen action. Your installed help file names that entry for your model and firmware.
Real platforms document the feature. One runtime logs an inactive operator off automatically after a time-out you set. One pairs its logout with a Return to graphic on logout checkbox on the Project Settings Runtime tab, and the logout loads the home graphic. One programming manual walks through reverting to the home screen after 60 seconds. At least one major panel family documents the opposite, with no built-in inactivity timer and no activity tag, so the search in step 1 comes before any PLC logic.
A screen saver that only dims the backlight is a different feature; it changes nothing on screen. If you want the lamp to sleep too, set it separately as covered in Set the HMI backlight saver timeout on a PLC panel.
What counts as operator activity
Decide the reset event before you build anything. The rule that works on a live floor: every touch on any screen resets the idle clock. If only two buttons reset it, an operator editing values three screens away gets bounced to home mid-entry, and the feature will be switched off within a week.
On the built-in route, read what resets the timer: some implementations count any touch, others count listed events only. Configure it so normal use of every screen counts.
On the PLC route the activity signal is yours to build. Give every interactive object a touch event that pulses one activity bit to the PLC for a single scan. If the panel raises events only on the objects you wire, wire the ones operators actually touch, and write the list into the project notes so the next engineer knows exactly which touches count. Keep the source on touch events. A tag that follows machine production tracks the machine's cycle, so it will reset the clock while nobody stands at the panel and miss the resets while someone does.
What you need
- The panel project file, open in its editing software, with a backup copy saved before you change anything
- Access to the PLC program and a documented download procedure for both projects
- The panel and runtime manuals for the installed versions, for the exact setting and register names
- A stopwatch for the 9-minute and 10-minute tests
Steps
- Search for a built-in return. In the editing software, check the panel settings, screen settings and navigation options for an inactivity, idle or screen-saver entry with a return-to-screen action. If it exists, set the time to 10 minutes, choose the home screen as the destination, note what resets it, then go to step 5.
- Confirm the screen-change write. The PLC route commands the panel through the link you already have. Many platforms expose the current screen number to the controller and accept a written screen number over the same link; on one major platform the manual calls the shared setting a global area pointer, and it reports screen and object changes too. Write the home screen number once from the PLC and watch the panel change screens. Test writes on an operator panel link before you depend on them; Operator panel PLC link setup: test writes before motion covers the procedure. Reading the current screen number back uses the same link, and Run PLC logic only on the HMI current screen number tag shows the tag-level detail.
- Build the activity bit. On every screen operators use, tie a touch event to one PLC bit, pulsed for one scan per touch.
- Add the idle timer and the return. Count seconds from the last qualifying touch with a 600-second preset, reset the timer to 0 on every activity pulse, and keep it non-retentive so a power cycle starts it fresh. When the timer finishes, write the home screen number into the panel's screen-change register, then clear the request the way the manual's handshake describes; a request left set will keep pulling the panel home. How panels move between screens is covered in Set up HMI screen navigation with change screen buttons.
- Download both projects through their documented procedures, and keep the previous working versions for rollback.
- Watch one full cycle. While you commission, put the timer's remaining value on the panel; Display a PLC countdown timer on an HMI panel shows the object. Remove it or keep it as a status line once the tests below pass.
Scenario: a milling cell returns home after 10 idle minutes
The cell panel runs screens 1 to 6. Screen 1 is home and screen 4 is tool offsets. The platform has no built-in return, so the PLC carries the logic: one activity bit, one 600-second non-retentive timer, one screen-change register.
At 07:31:00 the operator opens screen 4 and walks off. The last touch pulsed the activity bit, the timer reset to 0, and the count starts. At 07:40:00 the count stands at 540 seconds, 60 short of the preset, and the panel must still show screen 4. That is the 9-minute mark the first test below checks. At 07:41:00 the count reaches 600: 07:31:00 + 600 s = 07:41:00. The done bit fires, the PLC writes 1 into the screen-change register, and the panel lands on the home screen.
Second case, a touch just before the timeout. The operator comes back at 07:40:50, 570 seconds into the window, and edits one offset. The touch pulses the activity bit, the timer resets to 0, and the next return moves to 07:40:50 + 600 s = 07:50:50. The edit finishes undisturbed, which is the reason every touch feeds the reset.
For a second worked walkthrough of the same job on another platform, see a step-by-step guide to automatic home page return after an inactivity timeout.
How to check it worked
Run the tests with the machine in a safe state, and keep the previous project versions on hand so a bad download costs minutes.
- No early return. Open a setup screen, touch nothing, and check at 9 minutes (540 s) that the panel is still on it. At 10 minutes the home screen must be showing.
- Touch just before the timeout. At 9 minutes 50 seconds, touch any object the activity definition covers. The timer restarts and the return moves to a full 10 minutes from that touch.
- Every activity source. Press each kind of object your definition covers, numeric entry, list selection, navigation button, and confirm each one resets the clock.
- No loop after the return. When the panel lands on home, select another screen immediately and confirm it stays there. If the PLC request was never cleared, the panel snaps back within a scan or two; fix the handshake and repeat this test.
Recommendation: Use the panel's built-in inactivity return whenever its manual offers one: 10 minutes, home screen as the destination, reset on any touch. Build the PLC route only when the built-in return is absent, and only once the panel gives you a touch-activity bit and accepts a documented screen-number write. If the panel offers neither, rework the project so every screen pulses the activity bit, or ask the panel vendor which documented feature covers the job. Then hand the line back only after the 9-minute no-touch test and the touch-just-before-timeout test pass.
Questions
Should the idle return and the backlight saver use the same timeout?
They do different jobs. The backlight saver dims the lamp; the idle return changes screens. If you use both, put the saver after the return: a 15-minute saver against a 10-minute return means an operator who walks back always finds the home screen lit, and nobody presses a dark panel wondering whether it is off.
What happens to the idle timer after a power cut?
A standard non-retentive timer restarts at 0 when power returns, so the panel boots to its home screen with the idle clock fresh. Keep it that way: a retentive timer that carries 540 of 600 seconds across a power cut could push the panel home seconds after an operator starts working.
Does the PLC route work on a standalone panel with no controller?
A standalone panel can still have a built-in return, so check for it first. The PLC fallback needs the panel link, so with neither a built-in return nor a controller link there is no idle return to configure on that panel; moving between screens needs an interface the panel documents.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.