Functions
INSYS ISDN TA 4.0
9.4
Data Flow Control
The data flow control ensures that the data transfer is interrupted as soon as the
buffer of the INSYS ISDN TA 4.0 exceeds a certain level. Two data flow control
options are available: Via the control lines RTS and CTS, or via the control
characters XON/XOFF which are inserted into the data stream.
9.4.1
Hardware Data Flow Control (RTS/CTS)
The hardware data flow control works in two directions. When the critical buffer
level is exceeded, the INSYS ISDN TA 4.0 will set the CTS line to "low" and will
thus indicate to the application to interrupt the data flow. When the buffer is
emptied sufficiently for the INSYS ISDN TA 4.0 to be able to receive data again, the
CTS line is set to "high". Reversely, the application can also indicate to the INSYS
ISDN TA 4.0 to interrupt the data flow. This is done via the RTS line. If it is set to
"low", the INSYS ISDN TA 4.0 will interrupt the data flow to the application. The
application will set it to "high" to request data from the INSYS ISDN TA 4.0.
Data flow control is set to hardware as default setting.
Configuration with HSComm
The hardware 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 hardware data flow control
(RTS/CTS) with the command
AT&K=3
Disable the data flow control with the
command
AT&K=0
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