Case Communications Mayze 24, Reference Manual, Page: 67 / 166

system. The characters used to signal XON/XOFF can be changed to
suit special requirements.
RTS/CTS flow control uses hardware signals in the modem/DTE
interface to signal the start-sending and stop-sending conditions. This
type of control is useful when the data being transmitted is not in ASCII
form, to avoid data bytes being misinterpreted as XON/XOFF
commands.
In the factory-configured setting, command
%K2
is activated. This enables
the modem to use CTS, to flow-control data coming from the DTE, so that
the DTE speed may be set at a higher rate than the telephone line speed.
The flow control ON character is held in register S39, and the flow control
OFF character is held in register S40.
The factory default for S39 is 11 hex (DC1, Ctrl-Q), and for S40 it is 13 hex
(DC3, Ctrl-S). These are the standard XON/XOFF characters which are
generally used for modem flow control.
User Flow Control
User flow control is required when the rate at which data is received from
the line is greater than the rate at which the DTE can process it.
In the following example, the modem is receiving data from the line at
2400 bps, but the DTE can only process data at a lower rate.
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
Flow Control
a a a a a a a a a a a a a
a a a a a a a a a a a a a
a a a a a a a a a a a a a
a a a a a a a a a a a a a
Modem
a a a a a a a a a a
a a a a a a a a a a
a a a a a a a a a a
a a a a a a a a a a
Buffer
a a a a a a a a a a a
a a a a a a a a a a a
a a a a a a a a a a a
a a a a a a a a a a a
a a a a a a a a a a a
a a a a a a a a a a a
a a a a a a a a a a a
a a a a a a a a a a a
DTE's
Buffer
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a
a a a a a a a a a a a a a
a a a a a a a a a a a a a
a a a a a a a a a a a a a
a a a a a a a a a a a a a
a a a a a a a a a a a a a
DTE
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
Data 2400 bps
a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a
2400 bps
With %U enabled, the DTE controls when it can accept characters from the
modem. However, note that there is no control over data being received by
the modem from the line, so if data is being received continuously at a
greater rate than can be accepted by the DTE, the modem's receive buffer
will fill, causing data to be lost.
X460-306851 Issue 1 5-7 Rev.0