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3 INTEGRATING THE MAS-1

MAS-1

the current transmitted though the MAS-1. The red wire (see Fig-

ure 2) of the MAS-1 is connected to a voltage output terminal that

is able to supply 12 to 32 VDC. The black wire is connected to an

input terminal that accepts a current input ranging from 4 mA to

20 mA. For the MAS-1 to function properly, the voltage drop from

the red to the black lead must be 12 V or greater.

Figure 2: Typical Wiring Connection

Non-Conventional

When using a device, such as a data logger, that does not have

an input capable of measuring current a pickoﬀ resistor can be used

as shown in ﬁgure 3. Assuming that the single ended input has an

input impedance, or resistance, much larger that of R

, then all

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of the current in the 4-20 mA loop passes through R

. If the data

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logger can measure the voltage drop over the R

, then the current

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can be calculated as:

measured

I =

(1)

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where I (mA) is the 4-20 mA current, R

(ohms) is the resistance

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of the pickoﬀ resistor, and V

(mV) is the voltage drop over

measured

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