6100 BSC Programming Manual

Writing Applications that Use 6100 BSC
Shutting Down the Link
When all applications have closed the line, CP6100 disconnects
it, unless the parameter NOAUTOSTOP has been defined for the
line. A disconnect implies that if the line is switched, the
station sends the sequence DLE EOT and "hangs up the telephone"
by dropping DTR. The line state changes to DISCONNECTED, whether
the line is switched or leased. If the line is switched, BSC
also waits for DSR to drop, and reports an error if the signal
fails to drop within the disconnect timeout interval.
To disconnect the line, the application makes a CONTROL request
with the DISCONNECT option. Either station can make this request
in the course of any protocol transaction.
Closing the Line
When an application has finished its use of the line, or when
it does not expect to use the line for some period of time,
it makes a CLOSE call to correspond to every one of its OPEN
calls. When the line has been closed by all users, CP6100
makes a STOP request unless the NOAUTOSTOP parameter has been
defined for the line.
If the line is downloaded during error recovery, CP6100 closes
all opens if the AUTOCLOSE parameter has been defined for the
line.
3-19