Unsolicited Status Update Validation

Non ION USB PRTR mode doesn’t support USU function. Because USB device cannot communicate with the host unless the host specifically requests communication. PRTR mode uses Printer Class, it doesn’t have any specially requests from host as trigger to reply USU status.

The Host uses this command to determine if the device supports USU.

ASCII	GS a x
Hexadecimal	1D 61 x
Decimal	29 97 x
Value of x	0–FF

Response To Host (Hex)

1A, 9F, 1F

If the printer responds to the Unsolicited Status Update Validation message with this 3-byte response message, then the printer firmware supports the Unsolicited Status Update messages. If there is no response or the printer responds with some other sequence of bytes, then the printer does not support the Unsolicited Status Updates messages.

Note:  This command is ignored in Non ION USB PRTR mode.