Instruction manual

A758 Owner’s Guide Chapter 6: Communiction Interface
September 1999 93
XON/XOFF Protocol
The XON/XOFF characters coordinate the information transfer between the
printer and the host computer. The printer sends an XON character when it is
ready to receive data and it sends an XOFF character when it cannot accept any
more data. The software on the host computer must monitor the communication
link as shown in the following flowchart in order to send data at the appropriate
times.
If XON/XOFF has been selected, the printer also toggles the DTR signal, as
described in the next section, but it does not look at the DSR signal to transmit
data.
Host Flow Control Diagram
XON character = hexadecimal 11.
XOFF character = hexadecimal 13.
DTR/DSR Protocol
The DTR signal is used to control data transmission to and from the printer. It is
driven low when the printer is ready to receive data and driven high when it
cannot accept any more data. Data is transmitted from the printer after it
confirms that the DSR signal is low.