Ampro Corporation 486E Serial Ports J11, J13, RS-232C Serial Ports, RS-485 Serial Port, Addresses

Product Reference

Serial Ports (J11, J13)

Four RS-232C serial ports are included on the Little Board/486e CPU. Serial port 2 provides an optional RS-485 serial interface. Both serial ports support software selectable standard baud rates up to 115.2K baud, 5-8 data bits, and 1, 1.5, or 2 stop bits. The IEEE RS232C specification limits the serial port to 19.2K baud on cables up to 50 feet in length. The serial ports are based on a 16550 UART-compatible controller. This is an advanced UART that has a 16-byte FIFO buffer to improve throughput.

RS-232C Serial Ports

The Little Board/486e CPU can use 5BC sometimes as an alternate computer. Microprocessor system provides four standard RS-232C serial ports at J11 and J13 for use with:

!Printers

!Modems

!Terminals

!Remote hosts

!Touch input devices

!Any RS-232C serial device

Many devices require handshaking in one or both directions. Consult the documentation for any device(s) used for information about handshaking, cabling, and other interface considerations. Information about serial port configuration using SETUP, is provided in this chapter.

RS-485 Serial Port

An RS-485 option is available for Serial Port 2 at J11. Use of the RS-485 option offers a low cost, easy-to-use communications and networking multidrop interface that is ideally suited to a wide variety of embedded applications requiring low-to-medium-speed data transfer between two or more systems.

I/O Addresses

Serial port addresses are fixed and can not be changed. Each serial port, however, can be independently disabled using the SETUP function, freeing its I/O addresses for use by other devices installed on the PC/104 expansion bus. Port addresses are shown in Table 2–7.

Table 2–7. Serial Port I/O Addresses and Interrupts

Port	I/O Address	Interrupt
Serial 1	3F8h - 3FFh	4
Serial 2	2F8h - 2FFh	3
Serial 3	3E8h – 3EFh	7 or 11
Serial 4	2E8h – 2EFh	5 or 10

2–11