ZyXEL Elite 2864 User Guide - Page 51

Chapter 4 MODEM OPERATION Parallel or Serial Port Operation The 2864 models provide both a parallel port and a serial port for DTE connection, but only one out of three connection modes may be active at any time. The available modes are: • SP: Serial port mode; • PRP: Printer parallel port mode; • PCP: PC parallel port mode. Only when a port is actively driven and/or terminated externally may that port be active, i.e., the connected device must be turned on and must drive the port. An exception to this is the serial port. The modem defaults to the serial port if no active parallel port device is connected whether an active serial DTE is connected or not. The modem makes its port selection based on the serial port DTR signal. If it is ON, the modem defaults to serial port (SP) mode; if it is OFF, the modem seeks for an active parallel port device. If an active PC parallel port is connected, the modem will operate in PCP mode; if an active printer is connected, the modem will operate in PRP mode. If no active parallel port device is connected, the modem will default to SP mode. If both the modem's serial and parallel ports are actively connected and the parallel port is connected to a PC parallel port, the modem makes the port selection based on the serial port DTR signal. The serial port DTE can control the modem's active port through its DTR signal. If both the modem's serial port and parallel port are actively connected and the parallel port is connected to a printer, the modem also makes its port selection based on the serial port DTR signal. If the serial port DTR signal is OFF, the modem operates in PRP mode; if the serial port DTR signal is ON, the modem operates in SP mode. In Class Z mode operation for fax receiving and printing(explained in chapter 15), the modem will temporarily switch to PRP mode to print incoming faxes. If you use a serial port DTE that does not provide a DTR signal, make sure that no parallel port device is connected to the modem and that the modem defaults to serial port mode. You also need to set the modem DTR setting permanently to ON (&D0). 4-1