User`s guide

224 DC 900-1340I
BSC Programmer’s Guide
B.2 DSR/DCD Up/Down Reporting
If the data set ready (DSR) or the data carrier detect (DCD) modem signal (depending
on the setting of the modem control option, Section 6.15 on page 168) is lost while a
link is active, BSC 2780/3780 suspends line operations for that link and notifies the cli-
ent with the
DLI_PROT_RESP_ERROR error report containing the DLI_ICP_ERR_DSR_DOWN
error code. After reporting the DSR/DCD loss to the client, all message buffers that are
queued in memory for transmission remain in the queued state. If the signal is not
recovered, the BSC 2780/3780 software returns the queued message buffers to the client
when the client closes the session with
dlClose or issues a Flush Queue command
(Section 5.4.1.12 on page 130).
When the DSR/DCD signal returns, BSC sends the client the DLI_PROT_RESP_ERROR
error report containing the DLI_ICP_ERR_DSR_UP information code, and normal line oper-
ation resumes.
DSR/DCD up/down reporting is disabled when the modem control option is set to
HDX-2 or FDX-2.
B.3 Freeway/Line Interface
Freeway communicates to remote devices through serial connectors. The ports can be
connected to standard modem cables.
B.4 Modem Control Lines
Ta ble B –1 lists the EIA-232 modem control lines used by the BSC software.
B.5 Clock Signals
The BSC communication interface is designed to use either externally or internally gen-
erated clock signals. Clocking is selected through the clock source option (Section 6.2
on page 159). The BSC software always uses receive clocking provided by the receive