Drew Technologies DashDAQ XL, Instruction Manual, Page: 32 / 52

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The calculation is based on signals, so if you want to multiply/offset by a constant number you’ll need to create a signal with that
constant number. Fortunately this driver has two parameters that can generate signals with a constant value:
•
Constant Multiplier: Used to generate a signal called “Constant Multiplier”.
•
Constant Offset: Used to generate a signal called “Constant Offset”.
For example you could specify “3” as your Constant Multiplier value, pick Constant Multiplier as your Multiplier Signal, then your
calculation will multiply the incoming signal by 3. Finally, to keep things straight there are a few parameters to help you identify the
output signal:
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Name: Abbreviation to identify this signal. Used as a gauge label and displayed on the assign signals screen.
•
Units: Physical units for the calculation. Any automatic Imperial/Metric occurs afterward. For example, if a calculation results in
°C the number could be automatically converted to °F before display.
•
Precision: Number of decimal digits to display.
The calculated value will be available when you assign signals to a gauge (section 0).
EXAMPLE: DISPLAYING RPM AS 0-8 INSTEAD OF 0-8000
Some people prefer a tachometer that displays RPM x1000 because the gauge face has fewer unnecessary zeroes and looks less
cluttered. This calculation looks like:
Adjusted Tachometer = Engine RPM / 1000
To perform this calculation on the DashDAQ, try setting:
•
Input Signal: Engine RPM from GenericOBD2
•
Multiplier Signal:
Constant Multiplier from Rescale Signal
•
Multiplier Sign:
1 (Positive)
•
Constant Multiplier: 0.001. Represents the divide-by-1000
•
Offset Signal: Constant Multiplier from Rescale Signal
•
Constant Offset: 0 to add/subtract nothing
The calculated value will be available when you assign signals to a gauge (section 0).
EXAMPLE: CALCULATING BOOST
Many vehicles do not provide an enhanced signal for Turbo Boost but it’s pretty easy to calculate. We’ll assume that boost is the
additional manifold pressure above normal barometric pressure (~14.7psi). For example, MAP=19.7psi minus BARO=14.7psi implies that
the turbocharger is providing BOOST=5psi. This calculation looks like:
BOOST = MAP - BARO
To perform this calculation on the DashDAQ, try setting:
•
Input Signal:
Manifold Absolute Pressure from GenericOBD2
•
Multiplier Signal:
Constant Multiplier from Rescale Signal Calculator
•
Multiplier Sign: 1 (Positive)
•
Constant Multiplier: 1.0
•
Offset Signal: Barometric Pressure from GenericOBD2
•
Offset Sign: -1 (Subtract)
The calculated value will be available when you assign signals to a gauge (section 0).