6100 BSC Programming Manual

6100 BSC Concepts and Context
The value of BSCCONNECTTO<n> can range from 0 to 32767, and
expresses the timeout interval in 10-ms units. If the value is
0, BSC waits indefinitely for DSR. In general, if the line is
leased, the value can be quite small, because the modem keeps
DSR raised whenever power is on. In the case of a switched line
with the LIU on the receiving end, the value should reflect how
long it will take for a call to come in. If the LIU is on the
calling end with an operator dialing, the value should reflect
how long it takes for the operator to make the connection. The
default value is 3000 ms, or 30 seconds.
BSCDISCONNECTTO<n>. This parameter specifies how long the
protocol waits for DSR to drop after clearing DTR. It applies
only to switched lines. Because the purpose of clearing these
signals is to disconnect the line, this interval is sometimes
called the "disconnect timeout."
BSC clears DTR on either of two conditions: 1) the application
makes a CONTROL request to disconnect the line, or 2) the line is
closed by all applications. If DSR fails to drop within the
specified interval, BSC informs the application. A timeout
doesn't prevent the line from being disconnected, but it may
indicate a modem malfunction.
The value of BSCDISCONNECTTO<n> can range from 0 to 32767, and
expresses the timeout interval in 10-ms units. In general, a
very short interval is used. The default interval is 50 (half a
second).
NOTE
The definition of BSC includes a 20-second "disconnect
timeout." There is no relation between that timeout
and the one described here.
BSCFULL, BSCHALF. This parameter specifies whether the line is
full-duplex or half-duplex. By default, BSCHALF is in effect.
For half-duplex lines, BSC raises RTS before each transmission;
it waits for the modem to assert CTS, and then transmits the
data. For full-duplex lines, RTS is asserted whenever DTR is
present; still, CTS must be present for a transmission to
begin.
BSC does not permit two stations to transmit simultaneously. The
only advantage of full duplex lines is to reduce line-turnaround
delays.
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