ZyXEL Communications U-336R/RE Default Modem Settings for PC’s, ZyXEL Serial/Parallel I/O Card

your software supports it, replace the 16450 UART with a 16550 model. This newer chip has an internal buffer and generates an interrupt for up to every 16 characters (several trigger levels are available). With this UART installed, you may drive your serial port at 57600 bps and above.

While data is written from the transfer-buffer to your hard-disk, characters may be lost at the serial port. This is due to the fact that disk-access interrupts have a higher priority than serial port interrupts. If you are running at a high serial speed, e.g. 230.4Kbps or 460.8Kbps, on your PC, be sure to enable the disk cache by including SMARTDRV execution in your AUTOEXEC batch file.

Default Modem Settings for PC’s

Your modem’s factory settings are configured for operation with PC type computers and communication software. In most cases, no additional settings will be required. The following are some of the default settings that are used for operation with PC computers and software.

AT Command	Description
E1	Echoes command characters.
&C1	Carrier detect follows remote carrier.
&D2	Modem disconnects on DTR on-to-off transition.
&K4	Use both V.42 and MNP 4 error correction, and
	use both V.42bis and MNP 5 data compression.
&N0	Modem negotiates highest possible connection
	speed.

ZyXEL Serial/Parallel I/O Card

For high-speed PC to modem communication, ZyXEL produces a special I/O adapter card. This card includes a serial port and a parallel port, each with special features, particularly when working with a ZyXEL modem, for example:

Basic Modem Operation 25