^JU
Configuration UpdatePreview: not drawnSaves the printer's current settings so they survive a power cycle — or throws them away and starts from the defaults.
Syntax
^JUaParameters
| Parameter | Description and accepted values | If omitted |
|---|---|---|
| a | Save, load factory defaults, recall the last saved set, or load network defaults.S save current settings, F load factory defaults, R recall last saved, N load network defaults | None — the parameter is required |
How it works
^JU decides what happens to the settings a format has changed. Darkness, print mode, media type and the rest live in volatile memory until something commits them, and ^JUS is that commitment.
Without it, a printer configured by a ZPL file goes back to its previous settings the next time it is switched off and on — which is why a printer that 'forgets' its configuration overnight is almost always missing a ^JUS at the end of the file that set it up.
The other values go the other way: F loads the factory defaults, R recalls the last saved set, and N loads the network defaults. They are how you get a printer back to a known state before configuring it.
Example
^XA
^JUS
^FO50,50^A0N,40^FDSettings saved^FS
^XZRendering…
How the preview on this site handles it
Not drawn. ^JU writes to a printer's non-volatile memory, which a preview does not have. The format around it previews normally.
Common mistakes
- Configuring a printer and never saving. Everything reverts at the next power cycle.
- Saving on every label. ^JUS writes to flash, and flash has a finite number of writes — put it in the configuration file, not the template.
- Sending ^JUF in a template. Loading factory defaults mid-run resets everything the fleet was configured with.