Chapter 3 Example Applications
FieldPoint FP-3000 User Manual 3-2
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National Instruments Corporation
Example 1: Converting a 4–20 mA Pressure Sensor to Fieldbus Using FP-3000
One common application of the FP-3000 is interfacing to a conventional
device, such as a 4-20mA pressure sensor or a 4-20 mA temperature
transmitter. This example helps you configure the FP-3000 to interface to
a 4-20mA pressure sensor. This example shows you how to instantiate an
AI function block, assign a tag to the block, set up scaling parameters and
range for the I/O channel, schedule the function block, and download the
configuration to the FP-3000.

Getting Started

Example 1 requires the following materials:
• 4–20mA sensor, such as a pressure sensor
• FP-AI-100, FP-AI-110, or FP-AI-111 module (this example assumes
you are using the FP-AI-110 module)
• FP-3000 network module
• Host configuration system capable of instantiating function blocks on
devices (such as National Instruments NI-FBUS Configurator)
Wire the 4–20mA current loop into the current source input FP-AI-110
terminals. For channel zero, use terminals 1 and 17, as indicated on the
wiring diagram on the front of the FP-AI-110 module. Make sure your
current loop is powered and the sensor is operating normally.

Convert the Pressure Sensor Reading

Configure the software to perform the translation from the 4–20 mA sensor
signal to the engineering units used on the Fieldbus.

Create Function Block

You must create a block for the FP-AI-110 since the pressure sensor is
connected to a channel on the FP-AI-110 input module. To create a block
for the FP-AI-110, follow these steps:
1. Right-click on the FP-3000 entry in your configurator.
2. Select Instantiate New Block. This causes a dialog box listing all the
blocks supported by the FP-3000 to appear and allows them to be
instantiated.