VersaLogic STD32 VL-1225, Справочное руководство

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4-6
VL-1225/6 Analog Input/Output Board
Input Offset Binary Format (10-Bit Resolution)
Offset binary format is used with the bipolar ±5 or ±10V input ranges. 10-bit offset binary format divides
the full bipolar analog input range into 1024 steps. The code 0000H is associated with the most negative
voltage, i.e. –10 Volts. The largest code (03FFH) describes the most positive voltage, i.e., +9.9805 Volts.
An analog input of 0 Volts (ground) will read as 0200H. The upper six bits of the Data High register are
all zeros.
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 = A/D Conversion Data
Span = 9.98046875 (±10V Range)
4.99023437 (±5V Range)
Step = 0.01953125 (±10V Range)
0.00976563 (±5V Range)
Sample values are shown in the table below:
±5V Input ±10V Input Data Data
Voltage Voltage (Hex) (Decimal) Comment
+5.0000 +10.0000 — — Out of range
+4.9902 +9.9805 03FF 1023 Maximum positive voltage
+2.5000 +5.0000 0300 768 Positive half scale
+1.2500 +2.5000 0280 640 Positive quarter scale
+0.00977 +0.01953 0201 513 Positive 1 LSB
0.0000 0.0000 0200 512 Zero (ground input)
–0.00997 –0.01953 01FF 511 Negative 1 LSB
–1.2500 –2.5000 0180 384 Negative quarter scale
–2.5000 –5.0000 0100 256 Negative half scale
–5.0000 –10.0000 0000 0 Maximum negative voltage
Figure 4-4. Offset Binary Data Format (10-Bit Resolution)
Registers – Analog Input Registers