Definition
What is ESC/POS (Epson Standard Code for Printers)?
Epson Standard Code for Printers
The command language thermal receipt and kitchen printers speak. Instead of handing over a formatted page, a system opens a connection to the printer and writes a stream of bytes for text, line feeds, bold, a paper cut and a cash-drawer kick, which the printer carries out as they arrive.
In a Bangladeshi restaurant
A Dhaka restaurant puts an 80mm thermal printer on the kitchen shelf, gives it a fixed address on the restaurant's wifi such as 192.168.0.51, and leaves it listening on TCP port 9100. When the counter confirms an order, the billing system opens a socket to that address and writes the ticket as ESC/POS bytes; the paper moves and the printer cuts it by itself, with nobody pressing print. The receipt printer at the counter works the same way on its own address.
Common mistake
Assuming any printer will do. A USB-only or Bluetooth printer cannot be reached over the network at all, so nothing in another room can send it a ticket, and a printer with no Bengali font prints Bengali item names as blank space or boxes. Buy a network ESC/POS printer with an ethernet or wifi port, reserve a fixed IP so the address survives a router restart, and print one real Bengali menu item on that exact model before ordering the rest.
Not to be confused with
Not an office or laser printer driver: there the operating system hands over a laid-out page and the driver decides how it is drawn, while ESC/POS is the restaurant's system talking to the printer directly in the printer's own commands. It is also not the same as making a PDF receipt and letting the Windows spooler print it, because that route depends on a driver, a print queue and somebody's desktop staying awake.
Where it lives in Rosuii
Rosuii has automatic station jobs for configured network ESC/POS printers or supported Windows desktop printer mappings. Confirm the installed app, printer driver and Bangla output before service. Each kitchen gets its printer address in Settings → Kitchens, and something at the venue has to be running to reach it, either the Rosuii Windows or Android app or the Rosuii print agent, because a browser cannot open a printer socket.
See the feature in detail