INSYS ISDN TA 4.0
Functions
9.4.2
Software Data Flow Control with XON/XOFF
When the input buffer of the INSYS ISDN TA 4.0 exceeds a certain fill state, the
INSYS ISDN TA 4.0 will insert an XOFF character into the data stream to the
application. This character will cause the application to send no more data. It
depends on the according application software if the XON/XOFF data flow control
is supported.
After the input buffer of the INSYS ISDN TA 4.0 is emptied sufficiently that data
can be received again, the INSYS ISDN TA 4.0 will send an XON character to the
application. This character will cause the application to send data to the INSYS
ISDN TA 4.0 again. Analogously, the application can insert XON/XOFF characters
into the data stream to switch the data flow on and off. The XON/XOFF data flow
control is only available when the transmitted data do not contain the characters
XON or XOFF, which usually appear only in actual ASCII texts (7 bit). When binary
data (programs, etc.) are transmitted, or in the XMODEM transmission protocol, for
example, occasionally appearing XON or XOFF characters would disturb the
operation.
Configuration with HSComm
The software controlled data flow control is configured on the "ISDN" tab
in the "Handshake" panel (Figure 7, page 35, position 23).
Configuration with AT commands
Enable the software data flow control
XON/XOFF with the command
AT&K=4
Disable the data flow control with the
command
AT&K=0
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