Black Box MiniStat-Four, Руководство пользователя

Страница: 37 / 71

36
MINISTAT-FOUR
Procedure:
To change the status of software flow control, type the appropriate code number.
The new selection appears in the CURRENT STATE line.
Type
Q
to return to the SUB-CHANNEL CONFIGURATION screen.
12. END-TO-END SOFTWARE FLOW CONTROL Screen
Purpose: View the current status of end-to-end software flow control used on this
sub-channel and select, if desired, a new status.
Description:
In addition to the MiniStat-Four-to-DTE control function (subsection 11), the
MiniStat-Four provides a DTE-to-DTE (or “end-to-end”) flow-control function. This
function allows a receiving DTE that temporarily cannot accept new data to
command the remote transmitting DTE to interrupt data flow, and then send a
request to continue data flow.
By selecting the ON option on this screen, the MiniStat-Four is configured to
recognize the two special characters (selected by means of the screens presented in
subsections 3 and 4): X-OFF, which conveys the local DTE’s “stop flow” command,
and X-ON, which conveys the local DTE’s “restart flow” command.
The detected X-ON/X-OFF commands are sent to the remote MiniStat-Four,
which converts them to flow-control commands for the remote DTE connected to
it. When an X-OFF command is received from the local DTE, the local MiniStat-
Four immediately interrupts the transfer of received data to the local DTE. The
additional data sent by the remote DTE during the time it takes to transfer the
X-OFF command accumulates in mux buffers. Similarly, when an X-ON command
is received from the local DTE, the local mux immediately starts the transfer of any
accumulated received data.
The flow-control commands supplied to the remote DTE depend on the MiniStat-
Four-to-DTE flow control mode selected at the remote DTE: the same X-ON/
X-OFF characters, or use of CTS line (see subsection 11).
When the local MiniStat-Four does not have software flow-control capability, the
MiniStat-Four “end-to-end software flow control” must be configured as OFF, to
prevent the MiniStat-Four from responding to the X-ON and X-OFF characters.
In this case, see also subsection 13.