VersaLogic STD32 VL-1225, Справочное руководство

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4-10
VL-1225/6 Analog Input/Output Board
Analog Output Registers
Output Data Registers
Channel 0 (OD0) — FF0EH
Channel 1 (OD1) — FF0FH
7 6 5 4 3 2 1 0
DA7 DA6 DA5 DA4 DA3 DA2 DA1 DA0
Figure 4-11. Output Data Registers
The Output Data registers are write only registers used for D/A conversion. One register is assigned for
each output channel. Data may be written to these registers as fast as desired, since the D/A conversion
is virtually instantaneous.
DA7-DA0 — D/A Data.
The 8-bit data value written to these bits is converted to an analog output voltage.
See the Output Data Representation section for a discussion of output data formats.
Output Data Representation
The format of the data written to the Data Output registers depends on the output range and the output
data format that is selected. Each of the data formats is discussed below.
Output Binary Format
Binary format is used only with the unipolar 0 to +10V output range. Binary format divides the full 10
Volt analog output range into 256 steps of 39.06 mV each. The code 00H produces an analog output of 0
Volts. The largest code (FFH) produces a full scale analog output of +9.9609 Volts. All codes are considered
positive.
The formulas for calculating analog or binary digital values are given by:

Analog

Digital =

————

Analog = Step
×
Digital

Step

Where:
Analog = Output voltage
Digital = D/A Conversion Data
Step = 0.0390625
Output Data Data
Voltage (Hex) (Decimal) Comment
+10.0000 — — Out of range
+9.9951 FF 255 Maximum voltage
+5.0000 80 128 Half scale
+2.5000 40 64 Quarter scale
+1.2500 20 32 Eighth scale
+0.03906 01 1 1 LSB
0.0000 00 0 Zero
Figure 4-8. Binary Format
Registers – Analog Output Registers