232XSSD43800 Manual
17
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
time the command control string is sent. Note also, that if your
communication configuration is set for 7 data bits you cannot use the
eighth position of SW2. For a list of the ASCII character codes and
their decimal values refer to Appendix A.
Smart Switch/Port Combiner Mode
This mode allows the CTS lines of ports A - H of the 232XSSD4
to select the Master port. It also allows selection from the Master
port via the command control string described in the Smart Switch
Mode section. Position 6 of DIP switch 1 (SW1) must be in the ON
position to enable this mode. Refer to Figure 2. When all ports are
off and the CTS line (pin 5) goes high on any of the eight ports, a
connection is established from that port to the Master port. This
works on a first-come-first-serve basis and only for RS-232
configured ports. At power up in this mode there is no port selected.
For example, if port A of the 232XSSD4 wanted to established a
connection to the Master port, port A would raise its CTS line (pin 5)
high. The 232XSSD4 would recognize this as a prompt for
connection to the Master port. The connection would be dropped as
soon as the CTS line on port A was lowered. At that time any of the
other RS-232 ports on the 232XSSD4 can raise their CTS line to
establish connection. If port A is connected to the Master port and
any of the other RS-232 ports on the 232XSSD4 raises their CTS
line, the data sent to the 232XSSD4 from those ports would be lost.
The 232XSSD4 does not have buffering.
Note that when a port is selected via the Master port, the CTS
lines will be ignored until the Smart Switch receives the turn off
command from the Master port. When a CTS line selects the
Master port, all commands will be ignored until CTS goes low.
A typical application would be to tie CTS & RTS together on the
Master port. So when CTS on a port is raised, RTS on that port also
goes high establishing a connection for your hardware. Note that
RTS will be low until connection to the Master port has been
completed. The other ports will be held off because TD, RTS, and
DTR will be low. After CTS goes low, the 232XSSD4 will scan the
CTS lines starting with the next port. When there are no ports
selected Port A will have first priority, port B second and so on.
NOTE: The port combiner function is not available on the Port
Expander units.
