Figure 28 Xon/Xoff Serial Port Flow Control - TransAct Ithaca 90PLUS Series Programmer's Manual

Programmer's Guide
Figure 28 illustrates how the XON/XOFF protocol works.
Communications
Port
Serial
Data In
Data
Inquire
Serial
Commands
Data Out
Send
DTR
Send
Send
RTS
XON or XOFF
(Not Used For
Flow Control)
RTS Request To Send
DTR Data Terminal Ready

Figure 28 XON/XOFF serial port flow control

11/07/05
PcOS Series 90PLUS
ENQ
High
Proc.
Speed
Data
FIFO
ENQ Response
XOFF
Buffer Getting Full
Buffer Getting Empty
XON
Select Key
Software Printer
Data
Data
Print
Buffer
256 - 6K
Rev Q
Communications
Serial Port
Control
Page 139