AnalogIn calculation principle:

When Analogue input channels are configured to measure: 0-20mA / 4-20mA / 0-100mV, all analogue measurements are internally scaled into a floating-point value between 0 and 1.

The lowest transmitter signal equals 0 and the maximum transmitter signal equals 1.

Minimum transmitter signal is: 0mA or 4mA or 0V

Maximum transmitter signal is: 20mA or 100mV

If the transmitter signal is below the measurement range the value is negative.

If the transmitter signal is above the measurement range the value is greater than 1.

The calculation of AnalogIn is based on 2 constants per channel:

ZeroPoint: Process value for the minimum signal from the source transmitter

Span: Process value for the source transmitter’s measurement range.
(Maximum process value = ZeroPoint + Span)

AnalogIn is calculated using this formula:

AnalogIn := (Value * Span) + ZeroPoint.

(See also: AnalogIn, Span, ZeroPoint)

Example of converting a 4-20mA signal to a measurement value (AnalogIn) of 2 to 5 Bar:

AnalogIn calculation principle:

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