4-10
VL-12CT96/7 Analog & Digital I/O Card
Analog Output Registers
Analog Output Data Low Register
Channel 0 (DAC0LO) — 030CH
Channel 1 (DAC1LO) — 030EH
7
6
5
4
3
2
1
0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
Figure 4-14. D/A Data Low Register
The DAC0LO and DAC1LO registers are write registers which receive the lower 8 bits of data used for
D/A conversion. One register is assigned for each output channel. The registers are used in conjunction
with the DAC0HI and DAC1HI registers to provide the complete 12-bit data word.
The DACxLO register should be written to first, followed by the DACxHI register. A word-wide output
instruction to the DACxLO register (out ax,dx) will write data to both registers in the proper sequence.
This is true for both 8-bit and 16-bit modes as determined by jumper V8[1-2].
Data may be written to these registers as fast as desired, since the D/A conversion is virtually
instantaneous.
D7-D0 — D/A Output Data (Least Significant Byte).
The data written to these bits forms data bits D7
through D0 of the 12-bit digital value to be converted to an analog output voltage. See the D/A Data
Representation section on page 4-11 for a discussion of data format.
Analog Output Data High Register
Channel 0 (DAC0HI) — 030DH
Channel 1 (DAC1HI) — 030FH
7
6
5
4
3
2
1
0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
Figure 4-15. D/A Data High Register
The DAC0HI and DAC1HI registers are write registers which receive the upper 4 bits of data used for
D/A conversion. One register is assigned for each output channel. The registers are used in conjunction
with the DAC0LO and DAC1LO registers to provide the complete 12-bit data word.
When writing data, the DACxLO register should be written to first, followed by the DACxHI register.
The analog output value changes when DACxHI is updated. See the D/A Data Low Register section
for further information on register access.
D7-D4 — Not Used.
These bits have no function on the VL-12CT96/7.
D3-D0 — D/A Output Data (Most Significant Nibble).
The data written to these bits forms data bits D11
through D8 of the 12-bit digital value to be converted to an analog output voltage. See the D/A Data
Representation section on page 4-11 for a discussion of data format.
Registers — Analog Output Registers
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