2.4
Base Address
The DAQ-16 uses 16 consecutive I/O address locations in the range 0 to 0FFFFH. Two
six-position switches (SW1 and SW2) are used to select the base address. SW1 controls
address lines A15 - A10, and SW2 controls A9 - A4. Address lines A3 - A0 are used
internally by the DAQ-16 to select which register to access.
When selecting a base address for the DAQ-16, an address selection switch in the "OFF"
position corresponds to an address bit of "1" while a switch in the "ON" position corresponds
to an address bit of "0". The base address of the DAQ-16 must be set on a 16 byte boundary,
meaning A3 - A0 are "0". The address of the DAQ-16 as shipped from the factory is 0300H.
This setting and other examples are shown in the Figure 2-5.
O
N
1
2
3
4
5
6
O
N
1
2
3
4
5
6
0 0 0 0 0
1 1
0
0 0 0
0
3
0
0
Example1: Base I/O Address = 0300H
Bit=0 Bit=1
SW1
xxxx Hex
0000 : 0
0001 : 1
0010 : 2
0011 : 3
0100 : 4
0101 : 5
0110 : 6
0111 : 7
1000 : 8
1001 : 9
1010 : A
1011 : B
1100 : C
1101 : D
1110 : E
1111 : F
x x x x x
0000
O
N
1
2
3
4
5
6
O
N
1
2
3
4
5
6
SW2
x x x x x x
O
N
1
2
3
4
5
6
O
N
1
2
3
4
5
6
Example 2: Base I/O Address = 6AD0H
6
A
D
0
1 1 0 1 0
1 0
1
1 1 0
A A A A A A A A A A A
A
15 14 13 12 11 10 9 8 7 6 5 4
x
0
0
Figure 2-5. I/O Base Address Selection
DAQ-16 Users Manual 16
