Modes; Time-Based Switching - W&T Electronics RS232 Handbuch

W&T
RS232(/422/485) Universal Serial T-Switch

Modes

The RS232 Universal Serial T-Switch model 85643 offers
various operating modes, which are divided into the groups

. Time-based switching

. Switching with control sequences
and which are described in the following.
Time-based switching
Time-based switching mode is always useful when multiple
computers need to share a peripheral device and switching
needs to be automatic and without intervention by the user.
The principle is simple: when the T-switch while in its base state
r e c e i v e s a c h a r a c t e r o n P o r t A , a b i - d i r e c t i o n a l
connection is immediately opened between Ports A and C.
As long as there is data traffic on this connection, no
connection from B to C can be switched. Only if during
a settable time there is no longer any data traffic detected on
the active connection does the T-switch resume its base state.
Now if it receives a character on Port B, the connection between
B and C is switched and the connection from A to C blocked.
If the T-switch receives a character on Port C, no switching
takes place.
A character-activated path between Port A and C or Port B and
C supports bi-directional data transfer between the
respective connected ports. The return direction from Port C to
A or Port C to B is however not enabled until the data
sender on Port A or B has provided for opening of the
channel. If neither of the two paths is activated, any data
arriving at Port C are rejected.
In all time-based operating modes two LEDs on the front
panel of the T-switch are used to indicate which of the two avai-
lable data paths is currently active.
15
Subject to error and alteration