User`s guide

Card Setup

OMG-ISO-COMM Page 4

Interrupt Mode Options

Header E5 selects the interrupt mode for each port. Each port must be set in the

correct mode to insure proper installation.

‘N’ indicates the (N)ormal, single interrupt per port mode. ‘S’ Indicates the

(S)hared interrupt mode, which allows more than one port to access a single IRQ.

Any two or more ports can share a common IRQ by placing the jumpers on the

same IRQ setting, and setting the appropriate selections at E5. Consult your

particular software for IRQ selection. If no interrupt is desired, remove the

jumper. ‘M’ indicates the inclusion of a 1K ohm pull-down resistor required on

one port when sharing interrupts.

Figure 4 - Header E5, Normal IRQ Mode

Set jumpers to ‘S’ for shared interrupt mode on all blocks sharing an IRQ except

one. Set that port block for ‘M’. This provides the pull-down resistor circuit that

makes sharing of IRQs possible. If you are using more than one OMG-ISO-

COMM or a compatible card in a bus you should only have one port set to ‘M’.

The following example shows all four ports sharing a single IRQ.

1 2

Figure 5 - Header E5, Shared IRQ Mode