Axiohm 7156 Especificações descarregar pdf (Página 119)

7156 Owner’s Guide Commands

October 1995 111

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 out 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, an application should determine the cause of a

busy condition and take appropriate action or pace further real time commands

to avoid filling the buffer. There are a minimum of 256 bytes available in the

printer’s buffer when it goes busy.

Real Time Status Transmission

Transmits the selected one byte printer status specified by n in real time

according to the following parameters.

GS Sequence

Hex Decimal ASCII Value of n

1D 04 n 29 4 n GS EOT n

1 = Transmit printer status

2 = Transmit RS-232C busy status

3 = Transmit error status

4 = Transmit receipt paper status

5 = Transmit slip paper status

The command is ignored if n is out of range.

DLE Sequence

1 2 ... 114 115 116 117 118 119 120 121 122 123 124 ... 189 190

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