Instruction Manual

Card Setup
Sealevel Systems COMM+2/EX Page 4
Interrupt Modes
Headers E9 and E10 select the interrupt modes for each port. Each port must be set in the correct mode to insure
proper installation. E10 sets Port 1 and E9 sets Port 2
‘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 E1. 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.
E
1
0
E
9
N S M
N S M
Figure 4 - Headers E9 and E10, Normal IRQ Mode
Set the 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
COMM+2/EX or a compatible adapter in a bus you should only have one port set to ‘M’. The following example
shows both ports sharing a single IRQ.
E
1
0
E
9
N S M
N S M
Figure 5 - Headers E9 and E10, Shared IRQ Mode