Switch User Manual

232SS21600 Manual
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone]
8
Smart Switch/Port Combiner Mode
This mode allow Ports A-D to select the master port using a
handshake line. It also allows selection from the master port via the
preamble code described in the Smart Switch Only Mode section.
Position 7 of “SW1” must be ON to be in port combiner mode. When
a handshake line goes high on any of the four ports, it will establish
a connection from that port to the master port. This works on first-
come-first-serve basis. If multiple ports have their handshake lines
high, the port that has been waiting the longest will be next to be
connected to the master port. For example, (Initial conditions -- no
slave ports with handshake lines asserted.) in chronological order,
Port C asserts its handshake line, Port A asserts its handshake line,
Port D asserts its handshake line and then Port C disasserts its
handshake line. When Port C asserts its handshake line, a
connection will be made between the master port and Port C. When
Port C disasserts its handshake line, Port C will be disconnected
and Port A will be connected to the master port. When Port A
disasserts its handshake, Port A will be disconnected and Port D will
be connected to the master port.
The handshake line that is used to connect to the master port
depends on the configuration of the master port (which in turn
determines the configuration of the slave ports). If the master port is
configured as a DTE port, then the slave ports are configured as
DCE, and RTS must be raised by the device (which is DTE) to
connect to the master port. If the master port is configured as a DCE
port, then the slave ports are configured as DTE and CTS must be
raised by the device (which is DCE) to connect to the master port.
For example, port A is configured as a DCE port (slave device is
DTE), in order to establish a connection to the master port, the
device must set RTS high (assert). The 232SS2 would recognize
this as a prompt for connection to the master port. The connection
would be dropped as soon as RTS from the device is lowered. The
devices on ports B-D may raise RTS at any time to request a
connection. However, if port A is connected to the master port, any
data sent from the devices on ports B-D to the 232SS2 will be lost.
The 232SS2 does not have any buffering.
NOTE:
When a port is selected via the Master Port, the
handshake lines will be ignored until the Master Port sends
the turn off code. When the Master Port is selected by a
handshake line, all preamble codes will be ignored.