ZyXEL Communications Omni 288S User Manual page 42

&H0 disables flow control
&H3 sets CTS/RTS flow control
&H4 sets XON/XOFF flow control
Hardware CTS/RTS
This is a bi-directional flow control where CTS and RTS are RS232 signals
which must be available on your computer. When the modem's transmission buffer
is almost full, the modem will drop CTS to signal the DTE that it cannot accept
any more data. Turn ON the CTS to notify the DTE that it can keep sending data to
the modem. On the computer software side, when the receiving buffer of the
software is almost full, it will drop RTS to signal the modem to stop sending data
to the DTE. Turn ON the RTS and the modem will start sending data again to the
DTE. In asynchronous full-duplex applications, the Omni 288S always responds
to the RTS signal as a flow control signal. The Omni 288S defaults automatically
to this hardware flow control setting and it is a better choice.
Software XON/XOFF
This is a bi-directional flow control. XON and XOFF character defaults are
decimals 17 and 19. These can be changed by modifying the S-Registers 31 and
32. Both the modem and the DTE will treat XOFF as a signal to stop transmitting
data, and will treat XON as a signal to restart sending data. Modems will not send
these characters received from the local DTE to the remote modem.
Chapter 4 - Advanced Data Communications
4-8