TH320/TH420
Programmers Guide
71
Real-time commands
The real time commands provide an application interface to the printer even when the printer is not
handling other commands:
Real-time status transmission: GS (Hex 1D) sequence and DLE (Hex 10) sequence
Real-time request to printer: GS (Hex 1D) sequence and DLE (Hex 10) sequence
Real-time printer status transmission
The batch mode printer status commands are placed in the printer’s data buffer as they are received and
handled by the firmware in the order in which they were received. If the paper exhausts while printing data
that was in the buffer ahead of the status command, the printer goes busy at the RS-232c interface and
suspends processing the data in the buffer until paper is reloaded. This is true for all error conditions: knife
home error, thermal print head overheat, etc. In addition, there is no way to restart the printer after a paper
jam or to cancel a slip waiting condition when using the wait for slip command.
The real-time commands are implemented in two ways in order to overcome the limitations of batch
mode status commands. Both implementations offer the same functionality; which one you choose
depends on the current usage of your application.
Preferred implementation
For a new application the GS (1D) sequences are recommended to avoid possible misinterpretation of a
DLE (0x10) sequence as a clear printer (0x10 0, ASCII DLE NUL) command.
An application using these GS (1D) sequences, does not need to distinguish for the printer between the
new real time commands and the clear printer command. This implementation is ideal for an existing A756
application that already uses the clear printer command or for a new application being developed.
Alternate implementation
The alternate implementation uses the DLE (0x10) sequences as implemented on other printers. An
application using these DLE (0x10) sequences and the original A756 clear printer command (0x10) must
distinguish for the printer between the new real time commands and the clear printer command by adding a
NUL (0x00) to the clear printer command.
An application using these DLE (0x10) sequences must also send the second byte of the sequence within
100 milliseconds of the first, to prevent the first byte being mistaken for a clear printer command.
Rules for using real-time commands
Three situations must be understood when using real time commands.
First, the printer executes the real time command within a few m sec of detecting it in the input buffer and
will transmit status regardless of the condition of the DSR signal.
Second, the printer transmits status whenever it recognizes a real time status transmission command
sequence, even if that sequence happens to occur naturally within the data of another command, such as
graphics data.
In this case the sequence will also be handled correctly as the graphics data it is intended to be when the
graphics command is executed from the buffer.
Third, care must be taken not to insert a real time command into the data sequence of another command
that consists of two or more bytes.
In this case the printer will use the real time command sequence bytes instead of the other
command’s parameter bytes when finally executing that other command from the buffer; the other
command will NOT be executed correctly.
These three situations generally preclude use of standard DOS drivers for the serial communication ports
when using real time commands.
Содержание TH320
Страница 1: ...TH320 TH420 Two Color Thermal Impact Hybrid Printer Programmers Guide ...
Страница 75: ...TH320 TH420 Programmers Guide 67 ...
Страница 121: ...TH320 TH420 Programmers Guide 113 Character Sets Character code 437 USA Standard Europe ...
Страница 122: ...Programmers Guide TH320 420 114 Codepage 737 Greek ...
Страница 123: ...TH320 TH420 Programmers Guide 115 Codepage 850 Multilingual ...
Страница 124: ...Programmers Guide TH320 420 116 Codepage 852 Slavic ...
Страница 125: ...TH320 TH420 Programmers Guide 117 Codepage 857 Turkish ...
Страница 126: ...Programmers Guide TH320 420 118 Codepage 858 with Euro symbol ...
Страница 127: ...TH320 TH420 Programmers Guide 119 Codepage 860 Portuguese ...
Страница 128: ...Programmers Guide TH320 420 120 Codepage 862 Hebrew ...
Страница 129: ...TH320 TH420 Programmers Guide 121 Codepage 863 French Canadian ...
Страница 130: ...Programmers Guide TH320 420 122 Codepage 865 Nordic ...
Страница 131: ...TH320 TH420 Programmers Guide 123 Codepage 866 Cyrillic ...
Страница 132: ...Programmers Guide TH320 420 124 Codepage 1252 Windows Latin 1 ...
Страница 134: ...Programmers Guide TH320 420 126 Codepage 1255 Hebrew ...
Страница 142: ...Programmers Guide TH320 420 134 TH420 Additional Features ...
Страница 156: ......
Страница 157: ...TH320 TH420 Programmers Guide Wincor Nixdorf International GmbH D 33094 Paderborn ...