
7156 Owner’s Guide
Chapter 6: Commands
September 1997
91
The Real Time commands are implemented in two ways to correct these problems. Both
implementations offer the same functionality; which one you choose depends on the
current usage of your application.
First Implementation
For a new application the GS (Hex 1D) sequences of the first implementation are
recommended to avoid possible misinterpretation of a DLE (Hex 10) sequence as a Clear
Printer (Hex 10 0, ASCII DLE NUL)
command.
The first implementation builds upon the GS ENQ sequence as implemented on Epson’s
TM-930II™, TM-950™ and TM-U950™ by defining two new GS (Hex 1D) sequences to
provide the same functions as the DLE (Hex 10) sequences above, and to provide complete
backward compatibility to the original 7156 Clear Printer command.
An application using these GS (Hex 1D) sequences does not need to distinguish for the
printer between the new real time commands and the old Clear Printer command. This
implementation is ideal for an existing 7156 application which already uses the Clear
Printer command or for a new application being developed.
Alternate Implementation
The alternate implementation uses the DLE (Hex 10) sequences as implemented on Epson’s
TM-T85™ and TM-U950™. An application using these DLE (Hex 10) sequences and the
original 7156 Clear Printer command (0x10) must distinguish for the printer between the
new real time commands and the old Clear Printer command by adding a NUL (Hex 00) to
the Clear Printer command.
An application using these DLE (Hex 10) 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. This implementation is useful for an existing TM-T85™ or TM-
U950™ application which is being migrated to a 7156. This application would not be using
the 7156 Clear Printer command at all since it is not recognized by the Epson printers.
Note:
The DLE (Hex 10) sequences as implemented on Epson’s TM-T85™ and TM-U950™
are not exactly the same as those implemented on Epson’s TM-950™.
Both implementations also provide the original GS ENQ real time sequence in addition to
the newer real time sequences.
Rules for Using Real Time Commands
Three situations must be understood when using real time commands.
1. First, the printer executes the real time command upon receiving it and will transmit
status regardless of the condition of the DSR signal.
2. 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.
3. 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.
Содержание 7156
Страница 1: ...BD20 1436 A Issue B September 1997 NCR 7156 Thermal Receipt and Impact Slip RS232 Owner s Guide...
Страница 6: ...Contents 7156 Owner s Guide September 1997 iv...
Страница 31: ...7156 Owner s Guide Chapter 2 Setting Up and Using the Printer September 1997 25 Sample Print Test...
Страница 38: ...Chapter 3 Solving Problems 7156 Owner s Guide September 1997 32...
Страница 118: ...Chapter 6 Commands 7156 Owner s Guide September 1997 112...
Страница 122: ...Appendix A Specifications 7156 Owner s Guide September 1997 116...
Страница 129: ...7156 Owner s Guide Appendix B Print Characteristics September 1997 123...
Страница 130: ...Appendix B Print Characteristics 7156 Owner s Guide September 1997 124...
Страница 136: ...Index 7156 Owner s Guide September 1997 6...