VersaLogic STD32 VL-1225, Справочное руководство

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VL-1225/6 Analog Input/Output Board
4-11
Output Offset Binary Format
Offset binary format is used with the bipolar ±5 or ±10V output ranges. It divides the full bipolar analog
output range into 256 steps. The code 00H produces a negative full scale output, and the largest code (FFH)
produces a positive full scale output.
The formulas for calculating analog or offset binary digital values are given by:

Span

Digital =

———————

Analog = Step
×
( Digital – 1) – Span

Step

Where:
Analog = Applied voltage
Digital = D/A Conversion Data
Span = 9.921875 (±10V Range)
4.9609375 (±5V Range)
Step = 0.078125 (±10V Range)
0.0390625 (±5V Range)
Sample values are shown in the table below:
±5V Output ±10V Output Data Data
Voltage Voltage (Hex) (Decimal) Comment
+5.0000 +10.0000 — — Out of range
+4.9609 +9.9219 FF 255 Maximum positive voltage
+2.5000 +5.0000 C0 192 Positive half scale
+1.2500 +2.5000 A0 160 Positive quarter scale
+0.03906 +0.07813 81 129 Positive 1 LSB
0.0000 +0.0000 80 128 Zero Volts
– 0.03906 – 0.07813 7F 127 Negative 1 LSB
– 1.2500 – 2.5000 60 96 Negative quarter scale
– 2.5000 – 5.0000 40 64 Negative half scale
– 5.0000 – 10.0000 00 0 Maximum negative voltage
Figure 4-9. Offset Binary Format
Registers – Analog Output Registers