Download to the panel
Downloading is one button in the editor (the blue 
icon, or F5).
There is no separate application, you need neither Python nor PlatformIO,
and you do not have to know what happens underneath. This chapter is about
what happens underneath — because during commissioning it comes in useful
exactly once.
Two different things: the runtime and the program
| Runtime | Program (pack) | |
|---|---|---|
| what it is | the panel's firmware | your screens, tags and logic |
| when it is written | on a new board or a new ctrl32 version | on every project change |
| how | Flash runtime on the board page (over USB) | the button / F5 |
| takes | tens of seconds | seconds |
Changing a screen does not mean reflashing the panel. The visualization is data, not code — the panel reads it straight from flash.
Network upload and security
The network target uses the same web server the browser interface runs on — whoever can reach the panel over Ethernet or WiFi could replace the program. The WEBview settings page has Allow program upload over the network; switched off, the panel never registers the upload endpoint and only USB uploads work. The panel belongs on its own machine network in every case.
What happens when you press
- The editor builds the project into a binary pack. If the build fails, nothing else happens and a window opens with the whole output.
- The pack travels to the panel — the dialog offers two targets:
the USB cable (serial, 2 kB chunks, each acknowledged), or the
network address of the panel (an IP or
name.local, prefilled from the project's mDNS name). Both roads carry the same pack with the same guarantees. - It is written into the inactive slot — the panel has two (
visu_a,visu_b) and is currently running from one of them. - The panel verifies the whole pack: CRC, format, schema version and target board.
- Only then does it switch the active slot and restart.
A download cannot brick the panel
When anything is wrong — a broken cable, a bad pack, the wrong board — the switch simply does not happen. The old pack stays in the other slot and the panel keeps running. That is not luck; it is the point of having two slots.
Pick the port here
The port selector in both transfer dialogs starts empty and the action stays disabled until you choose one. Nothing is preselected on purpose: a port nobody picked reads as a setting, and the first sign that it was not would be bytes going to a device that is not there.
Why the panel refuses a pack
| Message | Cause |
|---|---|
ERR: size/slot |
the pack is larger than the partition (or the slot cannot be opened) |
ERR: crc |
the transfer was corrupted — try again, check the cable |
| invalid target | the project is for a different board than the one connected |
| old format version | the runtime is older than the pack → flash the runtime |
The target-board check is deliberately strict. A pack for a panel with a different display and different pins would load and run — and the machine would do something other than what you expect.
Transport: the cable, or the machine network
During commissioning the USB cable is the road that always works — and it is the only road for online monitoring, which therefore parks itself for the duration of a download and reconnects by itself after the panel restarts.
The network target carries the same pack with the same slot-and-verify guarantees, over the panel's own web server. Mind the security switch described above: a panel that accepts a program over the network belongs on its own machine network, never on one strangers can reach.
Download into a machine that is standing still
Writing to flash stalls cache access for both cores, so the logic does not run while it happens, even at the highest priority. The panel therefore allows a download only in STOP — the same reason big PLCs have a RUN/STOP switch.
Runtime
The firmware is written from a catalog of prebuilt binaries for the board
(runtimes/), not compiled on your PC. You need no toolchain installed
and you get exactly the binary we tested.
The editor flashes it itself — no esptool, no Python. The flash is read back and verified before the dialog says done, and the chip that answers on the port is compared with the one the runtime was built for: a wrong COM port is refused, not written. When the packaged runtime is older than the editor, the dialog prints its build date in orange — flash the runtime before you chase ghosts.
It runs on its own thread, so the editor keeps drawing meanwhile, and it does not touch the pack slots — your program stays in the panel after a runtime flash.
What is downloaded together with the program
The pack contains everything the panel needs, in one file:
- the header (magic, schema version, target board, CRC32),
- the tables of strings, tags, alarms and styles,
- assets (fonts, icons, images),
- screens,
- the compiled program and the ST source (used to prove identity when going online).
The panel parses nothing out of it — it maps it from flash and reads it directly. Loading a screen takes less than a millisecond.
Licence
Downloading into a real panel is a paid part. Drawing, programming and simulating work in DEMO too — see Licensing.