National Instruments AT-MIO-64F-5, User Manual

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Chapter 2 Configuration and Installation
© National Instruments Corporation 2-3 AT-MIO-64F-5 User Manual
AT Bus Interface
Operation of the AT-MIO-64F-5 multifunction I/O board is controlled through accesses to
registers within the board register set. Some of the registers in the register set retain data written
to them to determine board operation. Other registers in the register set contain important status
information necessary for the proper sequencing of events. Still other registers perform
functions by accessing them either by reading from or writing to their location. However, these
registers do not retain pertinent data when written to, nor do they provide pertinent status
information when read.
The PC defines accesses to plug-in boards to be I/O mapped accesses within the I/O space of the
computer. Locations are either written to or read from as bytes or words. Each register in the
register set is mapped to a certain offset from the base address selection of the board as read or
write, and as a word or byte location as defined by the decode circuitry.
Base I/O Address Selection
The AT-MIO-64F-5 is configured at the factory to a base I/O address of 220 hex. This base
address setting is suitable for most systems. However, if your system has other hardware at this
base I/O address, you must change either the AT-MIO-64F-5 base address DIP switch or the
other hardware base address to avoid a conflict. Figure 2-2 shows a graphical representation of
the base address selection DIP switch, and also shows how to reconfigure the selected base
address.
A. Switches Set to Base I/O Address of Hex 000
Switch down for 0
Switch up for 1
B. Switches Set to Base I/O Address of Hex 220 (Factory Setting)
F
O
F
O
N
1 2 3 4 5
U104
Switch down for 0
Switch up for 1
F
O
F
O
N
1 2 3 4 5
U104
A6 A8 A9 A5 A7
A6 A8 A9 A5
A7
Figure 2-2. Example Base I/O Address Switch Settings