USB PRTR and NHPI Real-time Command

For USB PRTR and NHPI interface, Real-time commands are immediately processed regardless of the condition of the receiving buffer and the printer status as soon as it is received.

PRTR

PRTR supports two types of data transfer endpoints, which are control transfer and BULK transfer. The Real-time command is sent through control transfer, while print data are sent through BULK transfer. Since the Real-time command is sent through control transfer, which is different endpoint from print data, the printer can process command and provide response immediately.

For Windows application, it is suggested to use deviceiocontrol for sending Real-time commands. For more information, refer to the following Microsoft webpage: https://learn.microsoft.com/en-us/windows/win32/devio/calling-deviceiocontrol.

NHPI

NHPI is a type of Human Interrupt Device (HID) interface. It has similar characteristics with PRTR, which uses Real-time command and print data for different transfer endpoints. The Real-time command is sent through HID feature set transfer, while print data are sent through Interrupt OUT transfer.

For Windows application, it is suggested to use HidD_SetFeature for sending Real‑time commands. For more information, refer to the following Microsoft webpage: https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/hidsdi/nf-hidsdi-hidd_setfeature