Compaq GS80, GS160, GS320 manual Through Mode, Local Mode

Through Mode

Through mode is the default operating mode. The SCM routes every character of data between the internal system COM1 port and the active external port, either the local port or the modem port. If a modem is connected, the data goes to the modem. The SCM filters the data for a specific escape sequence. If it detects the default escape sequence, “<Esc><Esc>scm”, it enters the SCM CLI.

Figure 8–2 illustrates the data flow in through mode. The internal system COM1 port is connected to one port of the DUART chip, and the other port is connected to an external modem port, providing full modem controls. The DUART is controlled by the SCM microprocessor, which moves characters between the two UART ports. The local port is always connected to the internal UART of the microprocessor. The escape sequence signals the SCM to enter the CLI. Data issued from the CLI is transmitted between the SCM microprocessor and the active port that enters the SCM.

NOTE: The internal system COM1 port should not be confused with the external COM1 serial port on the standard I/O module. The internal COM1 port is used by the system software to send data either to the COM1 port on the system or to the SCM modem port if a modem is connected.

Local Mode

You can set a local mode in which only the local channel can communicate with the system COM1 port. In local mode the modem is prevented from sending characters to the system COM1 port, but you can still enter the SCM from the modem.

Using the System Control Manager 8-7