Dataplex DPX-213, User Manual

Page: 40 / 93

AT COMMAND SET
Section 4
4-18
Copyright (C) Dataplex Pty Ltd
AT&K DTE Flow Control
Parameters : 0 to 3
Default
: 1 (Select Xon/Xoff Flow Control)
This command selects the method of handshaking between the DTE and the modem during
error correction, data compression or whenever the Constant Speed Interface is set at a
different rate to the line speed.
NOTE: Xon/Xoff flow control should NOT be used when passing binary, command or
executable files since they may contain Xoff characters without matching Xon
characters. The modem may appear to 'lock up' and Xoff characters may be
introduced or lost, thus corrupting the file. Use hardware flow control (RTS/CTS)
for binary file transfers.
AT&K0 - Disable flow control. The DTE must be careful not to overflow the buffers or
data will be lost.
AT&K1 - Xon/Xoff ( ###
q
/ ###
s
) enabled. The modem can control the flow of
data by issuing an Xoff to the DTE. The Xon and Xoff characters can be altered
from their defaults and are stored in locations S33 and S32 respectively. Both
the modem and the DTE must halt whenever they receive an Xoff character and
not restart until they receive an Xon character.
AT&K2 - Enables RTS/CTS hardware flow control. When set, the modem drops Clear To
Send (CTS) whenever the buffers are almost full. The DTE may also flow
control the modem by dropping RTS.
AT&K3 - Enables both RTS/CTS and Xon/Xoff flow control. This is equivalent to
issuing the commands AT&K1 and AT&K2. Be sure to terminate RTS and CTS
correctly when using this command.
NOTE: Whenever AT&K2 or 3 are invoked, the RTS and CTS leads must be correctly
driven and not left floating in the interface cable.