Line graph axis labels missing on a small HMI panel

What each symptom points to

• Grid draws, labels and division numbers missing. The object's bounds are smaller than the screen. On the 3-inch panel this exact combination appeared, and full-screen size removed it.
• Labels missing even at full screen. Check that the screen you edited is the one transferred and running, and that the X and Y label fields in the object's properties are filled. In this case the fields were configured, which is why size came first.
• Grid missing too, or the whole object blank. A different fault. Check the data source, the object's visibility condition and the screen selection before touching geometry.
• Editor preview shows labels, panel does not. Transfer and judge on the panel. The editor's rendering is not the test; the panel's is.

Set the graph to full screen first

1. Open the screen with the graph in the project editor. Write down the object's current position and size in pixels so you can put it back.
2. Size the object to the full screen, edge to edge.
3. Transfer the project to the panel the way you normally do and open that screen on the device.
4. Check both axes on the panel: X and Y labels, division numbers, grid.
5. If the labels return, size was the fault. Leave the graph full screen unless the screen needs other objects.

A visible grid means part of the object is drawing; it is not proof the label area fits. If the labels stay missing at full-screen size, stop resizing and go to the property checks below. Changing several settings in one pass buries the cause.

One safety note: if the graph carries alarm or limit values that operators act on, keep the screen out of service until the labels show. An unlabeled scale invites a wrong reading.

Example: a 3-inch panel one pixel smaller than the screen

The inputs, with where each comes from:

• Panel: a 3-inch HMI display. The case this article works from.
• Object: a line graph with X and Y axis labels configured in its properties.
• Size A, full screen: the object spans the editor's canvas edge to edge. Result on the panel: grid, labels and division numbers all show.
• Size B: 1 pixel smaller than the screen. Result on the panel: grid only. Labels and division numbers gone.

The rule in words: a line graph draws its labels and division numbers inside its own bounds. On this panel, the bounds have to equal the canvas for that label area to fit.

The arithmetic: Size A passes at full screen. Size B fails at full screen minus 1 pixel. Call the canvas width or height W pixels; the test brackets the threshold into a band from W down to W − 1, and that band is 1 pixel wide. No size smaller than the canvas passed on this panel, so the smallest size that passed is the full canvas.

The decision, with its threshold: publish the graph at full-screen size. Do not carve pixels off it for other objects, because the first pixel off already fails on this panel. If the screen needs more content, that content moves to a second screen or a separate board. On a different panel the band can sit somewhere else; the same bracket test finds it. The one-pixel result belongs to this panel and this project.

Object geometry is stored in pixels, which is why a one-pixel change is a real change and not a rounding artifact; the same pixel arithmetic is what lets two HMI panel sizes share one layout in pixels.

Step the size down one change at a time

When the graph has to share the screen, find your own threshold instead of guessing:

1. Start from the full-screen layout that passed on the panel.
2. Cut one dimension by ten pixels, transfer, and check the panel. On the 3-inch panel above, the first one-pixel step already fails, so the test ends there and the graph stays full screen.
3. Keep cutting in ten-pixel steps until the labels vanish. Note the failing size.
4. Return to the last size that showed the labels and close in with one-pixel steps if you need the space.
5. With the size fixed, test position on its own: keep width and height, move the object, check the panel again.
6. Record the final size and position with the project.

Change one thing per test. A resize, a property edit and a new transfer in the same pass cannot tell you which change moved the result. If translations are in play, leave spare room around the labels: process-HMI style guides tell you to reserve space because translated label text runs longer than the original.

Check the axis properties last

In this case the X and Y label fields were configured and the labels appeared once the size was right, so geometry came first. At a size that shows labels, open the object's properties and confirm both label fields carry the text you want. Change one property at a time, transfer, and recheck on the panel. If one axis shows labels and the other never does at the same size, work on that axis alone.

If the label fields themselves are missing from the properties, that is a different fault: adding trend plot axis labels when widget controls are missing covers that case.

When the graph cannot keep the screen

A full-screen graph leaves no room for anything else, and that is a layout decision, not a dead end:

• Move the other content to a second HMI screen and reach it with change-screen buttons. Setting up HMI screen navigation with change-screen buttons shows how that navigation goes together.
• Put the numbers operators read from a distance on a board of their own. We build shop-floor screens for that job: text sized on the FHWA planning figure of 30 ft of viewing distance per inch of capital letter height reads from across the floor, and 20 ft per inch is the safer figure when people read while walking. Start at the shop-floor screens category.
• If the labels never show even at full screen, stop changing settings and take the project to the panel vendor's support, with the details listed in the question above about what to send.
• If the layout genuinely needs a smaller graph and no tested size on this panel shows the labels, the panel is too small for the job. Choosing an HMI panel: test startup and runtime first covers what to check before you replace it.

What to do on your panel

Recommendation: Set the line graph object to full-screen size, transfer, and confirm the labels and division numbers on the panel before you touch any axis property. If the screen must carry other objects, step the size down one change at a time and keep the last size that still shows labels on both axes; if that size turns out to be full screen, as it did on the 3-inch panel here, move the other content to a second screen or a separate board instead of shrinking a graph that fails on its first pixel.

Questions