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Impulse 3055 User Manual

Page 6

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Card

Setup

Sealevel Systems ULTRA-485 Page

3

IRQ Selection

Header E1 selects the interrupt request for each serial port. If COM1: is selected,
the corresponding jumper must be on the IRQ4 setting. If COM2: is selected, the
corresponding jumper must be on IRQ3.

Note: Most communications software applications default COM3: to IRQ4 and

COM4: to IRQ3. This requires the sharing of interrupts between COM1:
and COM3:, and between COM2: and COM4:. While this is the default, it
is not always the preferred setting. Check your software configuration
instructions to determine the most appropriate IRQ selection.

2 3 4 5 7 10 11 12 15

E1

Figure 1 - Header E1, IRQ Selection

Any two or more ports can share a common IRQ by placing the jumpers on the
same IRQ setting at header E1 and setting the appropriate selections at E2.
Consult your particular software for IRQ selection. If no interrupt is desired,
remove the jumper.