Judge text size on the running HMI panel, not the editor canvas. In the reported case, text that overflowed a rectangle and a caption hidden on a small pushbutton both came up smaller and fit after upload. Verify at the operator's distance and change only what the panel clips.
When the editor draws a caption outside its rectangle and the panel draws the same caption inside it, the panel wins. In the reported case, on editor version 1.21, build 06.18E, text that spilled past a rectangle in the design view came up smaller and fit after upload. A caption the editor hid on a small gray pushbutton appeared in full on the panel. Treat the running panel as the reference view. Upload it, stand where the operator stands, and change only what the panel clips. This page gives the checks, the editor settings that bring the two views closer, and the arithmetic for deciding whether panel text is large enough.
What each symptom points to
Both views show one project, and each disagreement points somewhere specific:
- Text outside its rectangle in the editor, inside it on the panel. The design view draws that font larger than the runtime does. The object is big enough at the panel's size, so judge it there.
- Caption missing on a small button in the editor, present in full on the panel. At the editor's larger drawn size the caption exceeded the button. At the panel's smaller size the same caption fit.
- Every other object in place in both views. The project data is sound. This is a rendering difference between two views of one file, and only the panel's view reaches the operator.
- Text that looks right in the editor and comes out wrong on the panel. That is the opposite fault, with its cause in panel resolution and scaling; fixing an HMI numeric keypad that comes out too small on a high-resolution panel covers that case.
Why the two views disagree
A point size is a physical size, 72 points to the inch. Both views draw it in dots, and the canvas and the panel sit on different dot grids. Desktop display scaling rescales whatever the editor draws, so a scaled desktop moves the canvas copy while the panel stays fixed. The disagreement has a documented range. One editor case had the design view draw text at twice the size the runtime simulation and the panel drew. The case reported here over-drew enough to spill a label and hide a caption. Your editor's exact factor sits in its documentation; the canvas will not tell you.
Bring the editor view closer
Do these four things before trusting the canvas:
- Set the editor zoom to 100 percent, so one project dot is one canvas dot.
- Confirm the project targets the panel's actual pixel count, 640 x 480 in the common small-panel case, so the canvas grid matches the panel grid.
- Run the editor with the desktop's display scaling at 100 percent. If the editor shows objects but no text at all, HMI editor shows objects but no text: check Windows DPI is the first check.
- Look for a runtime setting that adapts fonts to the device. One documented editor family ships exactly that: "Adjust font size in style", under Runtime settings > General > Screen. Switch it on if your software has the equivalent.
Use the editor's runtime simulation as the middle check when it exists. In the documented double-size case, the simulation already drew the true smaller size while the design view stayed at twice. Sign off on the panel either way.
Judge the panel at the operator's distance
Upload the project and read the affected screen from where the operator works, about 3 ft for a panel at arm's length on a machine. Check the longest caption the object can display, and every state that changes the text. A short test label passes where the longest string fails.
For size, use the signage planning figures: 30 ft of viewing distance per inch of capital height (FHWA), tightened to 20 ft per inch when the reader must read fast, with line spacing at 1.7 times the capital height.
| Viewing distance | Planning minimum, 1 in per 30 ft | Fast reading, 1 in per 20 ft |
|---|---|---|
| 3 ft | 0.10 in | 0.15 in |
| 6 ft | 0.20 in | 0.30 in |
| 10 ft | 0.33 in | 0.50 in |
| 20 ft | 0.67 in | 1.00 in |
Keep alarm and interlock text above the fast-reading column. An operator squinting at a fault message is already behind the event. The same distance-to-size arithmetic decides what size digital signage screen you need once the audience sits farther from the glass.
If the panel clips or hides text, fix one object at a time. Raise the font or the object until the longest caption fits, upload, and verify on the panel before touching the next object. Save a copy of the known-good project first so you can go back.
Recommendation: keep the project as uploaded whenever the running panel shows every caption in full and its capitals clear the fast-reading column, 0.15 in at 3 ft. Resize a font or an object only when the panel itself clips or hides the longest caption. Verify the change on the panel, and note the panel-side result in the project so the next edit is judged there too.
Example: a 24 pt caption on a 10.4-inch, 640 x 480 panel from 3 ft
Inputs: a 24 pt caption, typical for labels and pushbuttons in this class of editor; a 10.4-inch, 640 x 480 panel, a common size for that generation, standing in because the reported case names no panel; a 3 ft operator distance; and the planning rule of 30 ft per inch of capital height, 20 ft for fast reading.
Rule in words: draw the caption both ways, editor and panel, in dots. Convert the panel's dots to inches of type. Compare the capital height against the distance rule.
The panel grid first: a 4:3, 10.4-inch panel is 10.4 x 0.8 = 8.32 in wide, so 640 dots over 8.32 in is 77 dots per inch. Now draw the caption two legitimate ways. At the canvas convention of 96 dots per inch, 24 pt is 0.33 in of type and draws as 0.33 x 96 = 32 dots. At physical size, 0.33 in of type gives 0.33 x 77 = 26 dots on the panel. Twenty-six dots against 32 is about 20 percent less type on the same 640-dot screen. That is the difference between spilling past a rectangle and fitting inside it.
On the panel, 26 dots at 77 dots per inch is 0.34 in of type. Capitals run about 0.7 of type height in most fonts, so 0.34 x 0.7 = 0.24 in of capitals. At 3 ft the rule needs 3 / 30 = 0.10 in planning and 3 / 20 = 0.15 in fast reading. So 0.24 in clears the fast-reading minimum by 60 percent.
Decision: keep the 24 pt caption and the object as they are. The editor's spill is a drawing artifact at these numbers, and the panel delivers legible text with margin. Move the same panel to 10 ft across a cell and the rule needs 10 / 30 = 0.33 in planning and 10 / 20 = 0.50 in fast reading. At 0.24 in it fails both, so that viewer needs larger type or shorter text, changed in the project and judged on the panel.
When the audience is the whole floor
A 10.4-inch panel serves one operator at arm's length and stops serving at distance. At 20 ft the fast-reading rule needs 20 / 20 = 1.00 in of capitals, and a 0.24 in caption is a quarter of that. When the floor needs counts or status from across the aisle, put up a screen sized for the distance. The shop-floor display boards section covers that job, and the HMI stays with the operator who touches it.
Questions
Why does my HMI editor draw text larger than the panel does?
The design canvas and the runtime draw one point size onto different dot grids. The desktop's display scaling can move the canvas copy as well. A documented editor case showed the design view at twice the runtime size. The case reported here came out about 20 percent smaller on the panel. The panel is the delivery view, so judge there.
Should I shrink the font because the text overflows in the editor?
No. In the reported case the panel drew the text smaller and inside the rectangle. Shrinking the programmed size would only cut the capital height the operator gets. Change the font only when the panel itself clips the longest caption. Then re-upload and read that caption on the panel.
How large should HMI text be for the viewing distance?
Work from 1 in of capital height per 30 ft of distance, or 1 in per 20 ft for fast reading. At 6 ft that means 0.20 in planning and 0.30 in fast reading. A 24 pt caption on a 77-dot-per-inch panel gives about 0.24 in, enough for planning but short of fast reading.
Is there a setting that makes the editor match the panel?
Some editors ship one. A documented editor family offers "Adjust font size in style" under Runtime settings > General > Screen, which adapts the design font to the device. Set the editor zoom to 100 percent. Set the desktop display scaling the editor runs under to 100 percent as well.
The button caption is missing in the editor. Is the button too small?
Check the panel before enlarging anything. The reported case had a caption invisible on a small gray pushbutton in the editor that displayed in full after upload. Enlarge the button only if the panel also hides or clips the caption. Test with the longest caption that button can show.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.