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2.7.2 - Converting Binary Readings to Voltages

This information is only needed when using low-level functions and other ways of getting binary readings. Readings in volts already have the calibration constants applied. The UD driver, for example, normally returns voltage readings unless binary readings are specifically requested.

Following are the nominal input voltage ranges for the analog inputs.

Table 2.7.2-1. Nominal analog input voltage ranges

  Gain Max V Min V
Unipolar 1 5.07 -0.01
Unipolar 2 2.53 -0.01
Unipolar 4 1.26 -0.01
Unipolar 8 0.62 -0.01
Bipolar 1 5.07 -5.18

The high-resolution converter on the UE9-Pro only supports the 0-5 and +/-5 volt ranges.

The readings returned by the analog inputs are raw binary values (low level functions). An approximate voltage conversion can be performed as:

Volts(uncalibrated) = (Bits/65536)*Span

Where span is the maximum voltage minus the minimum voltage from the table above. For a proper voltage conversion, though, use the calibration values (Slope and Offset) stored in the internal flash on the Control processor.

Volts = (Slope * Bits) + Offset

In both cases, “Bits” is always aligned to 16-bits, so if the raw binary value is 24-bit data it must be divided by 256 before converting to voltage. Binary readings are always unsigned integers.

Since the UE9 uses multiplexers, all channels (except 129-135 and 137-143) have the same calibration for a given input range.

See Section 5.6 for details about the location of the UE9 calibration constants