User`s manual

CYCOM 485 User's Guide
Interrupts
Set the interrupt with the interrupt level jumper (Figure 2) according to the following:
COM1 = IRQ 4
COM2 = IRQ 3
COM3 = IRQ 4 (or a unique IRQ if your PC's )
COM4 = IRQ 3 (BIOS requires one )
Figure 2. Jumper - Interrupt Levels for COM1/COM2
COM3 and COM4
In order to use COM3 or COM4 you will have to read your computer owner's manual and determine the method
of setting the interrupts for COM3 and COM4. There are different methods and the one employed by your
computer is dependent on the ROM BIOS installed in the computer.
For example, ZEOS computers require that you assign a unique IRQ number, such as IRQ5, to the COM3 or
COM4 port if you install one. The assignment is done in the BIOS setup.
With other computers, you use IRQ4 for COMs 1 and 3 and IRQ3 for COMs 2 and 4. The BIOS determines
which COM port to service even though the interrupt may have been generated by one of two COM ports.
The information for using COM3 and COM4 is in your computer’s owner's manual. It is not something we can
provide you with, nor guide you through.
Disabling Existing COM Ports
Your computer may have been supplied with a COM1 or COM2 port, or both. To use the CYCOM 485 at either
COM1 or COM2, you must disable or remove the COM hardware currently installed for that port number.
Some computers, especially older computers, have a board with one or more COM ports installed. Some
computers come with COM ports designed into the motherboard. Refer to your computer’s owner's manual to
determine which type you have.
If the COM ports in your computer are on a separate board you may be able to disable only that COM port
(COM1 or COM2) which would conflict with your choice for the C
YCOM 485. If you cannot disable the COM
port on the board, you could remove the board from the computer.
If the COM ports in your computer are built into the motherboard you will be able to disable one or both either
by switches and jumpers on the motherboard, or through ROM BIOS setup.
For example, the ZEOS Ambra computer comes equipped with two serial ports set for COM1 and COM2.
These can be disabled individually by jumper settings on the motherboard. Another of our computers allows
you to enable or disable the COM ports via the BIOS setup options which are available by pressing F2 while the
computer is booting up.
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