Show a moving logo on an HMI during idle time

What the screen saver delay actually does

The setting lives in the panel setup of the programming software. On panel families that use the common layout it is under Setup → Panel Manager → General, as a project-level setting next to the backlight saver timer. The value is minutes: 0 disables the screen saver, and 1 to 1500 minutes is the working range. When the delay expires the panel turns the backlight off, and a touch wakes it again.

The name oversells it. This screen saver saves the backlight and nothing else. Backlight life ratings count lit hours, and 50,000 hours to half brightness is a common rating for a color LCD panel, so every hour the backlight is off is free and every hour it is lit is spent. There is no logo, image or screen-select field behind the delay, so the panel draws nothing during it. The moving logo has to be a screen in your project, and the trigger for it has to be a timer you own.

The timeout itself is covered step by step in set the HMI backlight saver timeout on a PLC panel, and the wake-by-touch behavior in turn an idle HMI screen off after 30 seconds and wake it by touch.

What you need

• The panel project and the PLC program open in your programming software, on the bench copies.
• The logo as a short sequence of bitmap frames, all one pixel size, or as a single bitmap repositioned by a numeric tag.
• One spare screen number in the panel project.
• In the PLC: one on-delay timer run as an inactivity timer, one integer register for the stored screen number, and an activity signal that changes whenever an operator acts.

The inactivity logic is the same pattern used to return an HMI screen to its home screen after 10 minutes idle: a timer that resets every time the operator does something.

Build the logo screen and the PLC idle timer

1. Make the logo screen. New screen, plain dark background, animated bitmap object centered on it, nothing else on the screen. Note its number; the example below uses screen 40.
2. Pick the activity signal. Use a tag that changes on every operator action: the panel's current screen number read by the PLC, a bit pulsed by operator-written objects, or keypad writes. Every screen an operator works on must reach this signal, or someone mid-task gets bumped to the logo.
3. Run the idle timer. Reset it on every change of the activity signal so it times out only on true inactivity, and preset it to the logo delay. Start at 5 minutes, which is a 300 s preset.
4. Store, then switch. On timer done, latch the panel's current screen number into the stored-screen register on the transition edge, then write the logo screen number to the panel's screen-change register. The edge store matters: if the PLC copies the current screen number every scan, the stored value becomes screen 40 and the operator returns to the logo forever.
5. Give the touch a job and no other. On the logo screen, add a full-screen invisible touch region. Its action writes the stored screen number back to the screen-change register and resets the idle timer. Put no live buttons on this screen; the touch that wakes the panel must not also start anything.
6. Override for alarms. In the alarm logic, write the alarm banner screen number straight to the screen-change register whenever an alarm or interlock bit sets. If the backlight is already blank at that moment, the PLC can also drive the wake described in wake an HMI panel's backlight from a PLC event. A logo hiding a fault banner is a production and safety problem, so this step ships with the logo screen.
7. Set the screen saver delay longer. Panel manager delay above the logo timer, on purpose, with both values written on the panel drawing. With a 5-minute logo timer, a 15-minute screen saver delay gives the logo a 10-minute run before the backlight blanks.

Example: packaging line panel, logo after 5 minutes

Operators use this panel in bursts and then leave it for the line. Settings: logo timer preset 300 s (5 min), screen saver delay 900 s (15 min), logo built as 10 frames at 200 ms per frame.

Last operator touch at t = 0. The idle timer reaches 300 s, its done bit fires, and the PLC stores the current screen and writes screen 40. The animated logo now runs from 300 s to 900 s. One animation loop takes 10 × 200 ms = 2000 ms = 2 s, so the 600 s window holds 600 ÷ 2 = 300 loops. At 900 s the panel manager delay expires, the backlight goes off, and the lit-hours clock stops with the logo hidden.

An operator touches the blank panel at 20 min. The backlight returns, the invisible touch region writes the stored screen number back, and the idle timer resets. If nobody comes back, the logo returns at 25 min. The 15-minute idle stretch used 10 minutes of lit logo and 5 minutes of blank panel, and it interrupted nobody.

Check it worked

• Hold a stopwatch against the panel: the logo screen appears 5 minutes after the last touch, give or take a PLC scan.
• Confirm the bitmap animates and that touch response on the logo screen stays brisk. Sluggish touches mean the frame sequence is too heavy: cut frames or lengthen the frame time before touching anything else.
• Touch the logo screen: the panel returns to the screen you left, and nothing on that screen operates.
• Force a test alarm with the logo up: the alarm banner replaces the logo immediately.
• Let the idle run past the screen saver delay: the backlight blanks.
• Power-cycle the panel and the PLC, with the stored-screen register initialized to the home screen number at PLC start, so a cold boot cannot send the panel to screen 40 or to an out-of-range number.

The decision for each case

• Branding between jobs, operators nearby: build the logo screen as above, logo timer at 5 minutes, screen saver delay at 15 minutes.
• Backlight life first: skip the logo screen and shorten the screen saver delay to about 5 minutes. If the panel must show something at shift start, the PLC schedule that wakes an HMI screen from screen saver on a schedule brings it back at a time you choose.
• Unattended readability: set the screen saver to 0, accept the lit hours, and keep the alarm banner on the base screen so faults stay visible with nobody at the panel.

If the real goal is idle-time branding or a notice board, a separate small shop-floor screen playing logo and notice files from a memory card or USB stick does that job without touching the PLC program; that is the job we build the displays in our factory floor screens category for.

Recommendation: Run the logo timer at 5 minutes and the panel manager screen saver at 15 minutes on any panel operators touch in bursts, and keep the screen saver delay at least 5 minutes longer than the logo timer so the logo gets a real run. Set the screen saver to 0 only where the panel must stay readable with nobody near it, and put the alarm override in before the logo screen ships.

Questions