User manual

APOS Premium Printer Series User Manual Page 92 /136 Reference: FDE 3107312 Issue A

OVING DATA THROUGH THE BUFFER

Applications should not let the buffer fill up with Real Time commands when the printer is busy at the

communication interface. A busy condition can be determined by bit 3 of the response to GS ENQ or GS

EOT 1 or DLE EOT 1. Other responses to GS EOT n or DLE EOT n can determine the reason for a

particular busy condition.

Although the printer responds to Real Time commands when it is busy, it will place them into the buffer

behind any other data there, and flush them out in the order in which they were received.

When the printer is busy due simply to buffer full (that is, it can’t print data as fast as it can receive it), then

data continues to be processed out of the buffer at approximately print speed and the Real Time commands

will eventually get flushed out.

When the printer is busy due to an error condition, then data stops being processed of the buffer until the

condition clears one way or another. In either case, but more quickly in the case of an error condition, the

buffer can fill with Real Time commands.

When the DLE sequences are being used, the last byte stored when the buffer fills up could be the DLE

code, with no room for the subsequent EOT or ENQ. When this lone DLE byte is finally processed out of

the buffer it will be interpreted as a Clear Printer command.

Similarly, when the GS sequences are being used, the last byte stored when the buffer fills up could be the

GS code, with no room for the subsequent EOT or ETX or ENQ. When this lone GS byte is finally

processed out of the buffer it will use the next byte, whatever it is, as the second byte in its GS sequence.

To guard against this situation, the application must determine the cause of a busy condition and take

appropriate action or pace the Real Time commands to avoid filling the buffer. There is a minimum of 256

bytes available in the printer’s buffer when it goes busy.

USY LINE AND FAULT CONDITIONS

If the printer is in error condition (cover is open, paper is exhausted…), the printer will still accept data,

respond to the batch mode status commands (ESC v and ESC u) and not go busy until it actually tries to

execute a print command. Then it will stay busy and stop processing data out of the receive buffer until the

condition clears. It will respond to the Real Time commands as described below.

EAL TIME RECOVERY FROM FAULT

This command will select the recovery mode when the printer detects a fault condition. Any fault condition

that prevents the printer from any printing function requires one of these commands to allow printing to

resume.

DLE Sequence

ASCII

DLE ENQ n

Hexadecimal 10 05 n

Decimal

16 5 n

Operand

n = recovery mode

Limit

Decimal:

1 ≤ n ≤ 2

Hex:

01 ≤ n ≤ 02

“DLE ENQ” OPERAND DEFINITION