B&B Electronics 232MSS2 manual Smart Switch/Port Combiner Mode

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 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 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 to connect to the master port.

For example, port A is configured as a DTE port. In order to establish a connection to the master port, port A must set CTS high (assert). The 232MSS2 would recognize this as a prompt for connection to the master port. The connection would be dropped as soon as CTS on port A is brought low. Ports B-D may raise CTS 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 232MSS2 will be lost. The 232MSS2 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.

8Documentation Number 232MSS2-0108 Manual

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