Specifications

7193 Owner’s Guide Chapter 6: Commands
August 1998 71
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 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.
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.
Moving Data Through the Buffer
Applications should not let the buffer fill up with Real Time commands when the printer is
busy at the RS-232C interface. A busy condition at the RS-232C interface can be determined
by bit 3 of the response to GS ENQ or GS EOT 1 or DLE EOT 1. The reason for a
particular busy condition can be determined by other responses to GS EOT n or DLE
EOT n.
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.