M-S Cash Drawer 7193 - Manual (Page 91)

Commands 7193 Owner’s Guide
May 1996 88
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 7193 Clear Printer command 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 7193.
This application would not be using the 7193 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™.
This implementation also provides 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 receives the Real Time status
transmission command sequence, even if that sequence happens to occur
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 send a Real Time command within 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 bytes when finally executing that other
command from the buffer or 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.