Emerson Process Management 3051N Sensor Temperature, Basic Setup, Set Process Variable Units

Rosemount 3051N

Reference Manual

00809-0100-4808, Rev CA June 2008

NOTE

Regardless of the range points, the Rosemount 3051N will measure and report all readings within the digital limits of the sensor. For example, if the

4 and 20 mA points are set to 0 and 10 in H2O on a range code 1 Rosemount 3051N, and the transmitter detects a pressure of 25 inH2O, it digitally outputs the 25 inH2O reading and a 250% of span reading. However, there may be up to ±5.0% error associated with output outside of the range points.

Sensor Temperature

HART Comm. 1, 1, 4

The Rosemount 3051N contains a temperature sensor just above its pressure sensor in the sensor module. When reading this temperature, keep in mind that this is not a process temperature reading.

BASIC SETUP

Set Process Variable Units

HART Comm. 1, 3, 2

Set Output

HART Comm. 1, 3, 5

The PV Unit command sets the process variable units to allow you to monitor your process using the appropriate units of measure. Select from the following engineering units:

•	inH2O	•	bar
•	inHg	•	mbar
•	ftH2O	•	g/cm2
•	mmH2O	•	kg/cm2
•	mmHg	•	Pa
•	psi	•	kPa
•	torr	•	atm
• inH2O at 4 °C		• mmH2O at 4 °C

Activate the transmitter square root output option to make the analog output proportional to flow. As the input approaches zero, the Rosemount 3051N automatically switches to a linear output in order to ensure a more smooth, stable output near zero. See Figure 2-5.

The transition from linear to square root is not adjustable. It occurs at 0.8% of ranged pressure input or 8.9% of full-scale flow output.

From 0 percent to 0.6 percent of the ranged pressure input, the slope of the curve is unity (y = x). This allows accurate calibration near zero. Greater slopes would cause large changes in output for small changes at input. From

0.6percent to 0.8 percent, the slope of the curve equals 42 (y = 42x) to achieve continuous transition from linear to square root at the transition point.

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