Ampro Corporation 486E - Manual (Page 27)

Product Reference
2–11
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