Impulse 3420 - Manual (Page 8)

Card Setup
Sealevel Systems COMM+8 Page 5
Interrupt Mode Options
The COMM+8 will allow each port to have an independent interrupt level
or share an interrupt with another port on the adapter. The COMM+8 will
even share interrupts with a compatible port that is located on another
adapter. The COMM+8 can operate in three interrupt modes. Header E9
determines the interrupt mode for Ports 1-4 and header E10 determines the
interrupt mode for ports 5-8.
“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-E8. 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.
1
2 3
4
5
6 7
8
N S M N S M
E9
E10
Figure 4 - Header E9 and E10, 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 IRQ sharing possible. If you are using more than
one COMM+8 or a compatible adapter in a bus you should only have one
port set to “M”. The following example shows all eight ports sharing a
single IRQ.
1
2 3
4
5
6 7
8
N S M N S M
E9
E10
Figure 5 - Header E9 and E10, Shared IRQ Mode