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Input and Channel Configuration
Mx+B, Alarms, and Channel Options 3
3-29
Mx+B, Alarms, and Channel Options
The subsequent sections supply information and procedures on how to apply Mx+B
scaling, set up channel alarms, and configure additional channel options.
Mx+B Scaling
Mx+B is a calculation that can be applied to a channel to scale a measurement value. This
feature is useful in applications where an input measurement needs to be converted to a
different unit or value to simulate an output. Common scaling conversions are:
• Scaling of a milliamp output of a pressure transducer to the equivalent kPa or psi
value.
• Scaling of a temperature reading from degrees Celsius to kelvins.
• Conversion of shunt resistor voltage to current in amperes.
To calculate Mx+B, the "M" value is referred to as the “gain” and is used as a multiplier
of the actual reading. After the gain is calculated, the "B" value or the “offset” is added to
the resultant.
For example, if a channel measures a voltage of 3 volts and the gain was set to 3.3, the
measurement on the display would read 9.9 volts (3 V * 3.3 gain = 9.9 V). Now the offset
is added to the gain. If the offset was set to 11.0, it would be added to the 9.9 volts and
the display would read 20.9 volts (9.9 V + 11.0 offset = 20.9 V).
More examples:
(6.9 gain * 20 mA) + 16.0 offset = 154 kPa
(1.0 gain * 25.0 °C) + 273.15 offset = 298.15 K
(10.0 gain * 0.32 V) + 0.0 offset = 3.2 A
If necessary, the Mx+B menu lets the user designate a new unit to accurately represent
the scaled measurement. This unit shows on the display and in the recorded scan data as
long as Mx+B is set to ON. If the Mx+B is set to OFF, the unit reverts back to the
original unit. When a channel has Mx+B scaling applied, a [Mx+B] icon is shown above
the unit next to the measurement value.
Note
If the scaled value is too large, "OL" (overload) is displayed. Adjust the
gain or the offset and try again.
1.888.610.7664 sales@GlobalTestSupply.com
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