Interrupt Level Selection - National Instruments VXI-AT2023 Getting Started

Hardware Configuration and Installation
Table 2-2. Possible Base I/O Address Settings for the AT-MXI (continued)
Switch Setting
A9 A8 A7 A6 A5
1 1 0 1 1
1 1 1 0 0
1 1 1 0 1
1 1 1 1 0
1 1 1 1 1

Interrupt Level Selection

The AT-MXI interface board can use either one or two of the eleven interrupt levels of the PC AT
I/O channel. Setting up an interrupt level for operation involves two steps. First you select the
interrupt level by arranging the jumpers on an array of pins. Next you enable the interrupt level in
the system software.
Note: You must enable the interrupt levels in the system software before they can function. If
you do not enable the interrupt level, that level will not be driven and can be used by
other devices, regardless of the positions of the jumpers.
Interrupt levels are selected by the position of two jumpers on the 3 by 11 array of pins labeled W3,
located above the I/O card-edge connector on the AT-MXI (refer to Figure 2-1). Use the jumper
farther from the card-edge connector to select the PC AT interrupt level that will convey board
status and error information. Remember to enable this level, or board interrupt, in the system
software for the AT-MXI to function properly. The factory default setting is level 12 and is enabled
on this level by the default configuration software.
Use the jumper on the W3 pin array closer to the I/O card-edge connector to select which PC AT
interrupt level corresponds to the MXIbus interrupt signal IRQ*. Because the MXIbus interrupt is
also one of the conditions covered by the other jumper, you normally do not need to use a separate
interrupt level for the MXIbus IRQ* signal; it is useful only if you want a different interrupt vector
or priority for MXIbus interrupts. This jumper is set at the factory to a default level of 10.
Note: The AT-MXI does not have the ability to share interrupt levels with other devices. If
you select an interrupt level by placing a jumper on a particular level and enable that
level in software, no other device in the system can use that level. Make sure that no
other devices in your system use the interrupt level(s) selected and enabled for use by
the AT-MXI. If they do, change the interrupt level(s) of either the AT-MXI or the other
devices. If you change an AT-MXI interrupt level, make a corresponding change to the
AT-MXI configuration software as described in the Configuring the NI-VXI Software
section of Chapter 3.
VXI-AT2023/NI-VXI ISC 386/ix Getting Started
Base I/O Address
(hex)
360
380
3A0
3C0
3E0
2-6
I/O Ports Used
(hex)
360 - 37F
380 - 39F
3A0 - 3BF
3C0 - 3DF
3E0 - 3FF
© National Instruments Corporation
Chapter 2