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Chapter 3 Example Applications
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National Instruments Corporation 3-7 FieldPoint FP-3000 User Manual
Wire the thermocouple to channel zero of the FP-TC-120 module, paying
attention to the polarity of the thermocouple wires. Channel zero is between
terminals 1 and 2 of the FP-TC-120. Next, wire the heating element (say, a
small light bulb or even a resistor) to channel zero of the FP-AO-200
module, which is between terminals 1 and 2 of the FP-AO-200.
You also need to connect a power supply to the V and C terminals of the
FP-AO-200 module to source power on the output channel. Refer to the
FP-AO-200 Installation Guide for more information.
Taking Temperature Readings
Create an FP-TC-120 Block
Once the hardware for control loop has been installed, you need to
instantiate, or create, an I/O block for the thermocouple input channel.
Since the thermocouple for this block is connected to a thermocouple input
module, you must create a block. To instantiate an I/O block, follow these
steps:
1. Right-click on FP-3000 in the configurator.
2. Select Instantiate New Block. This causes a dialog box to appear that
lists all of the blocks supported by the FP-3000 and allows them to be
instantiated.
3. Select FP TC 120 Block from the list, then click on the OK button.
Assign a Tag to the New Block
By default, new blocks are created without a tag. To assign a tag, follow
these steps:
1. Right-click on the new block, then select Set Tag.
2. Enter the tag you choose in the dialog box. The tag can be up to
32 characters in length and should not contain the dot (“.”) character.
3. Click on OK.
Select the Module and Channel
Determine the FieldPoint module number by counting each module in the
order it is attached to the FP-3000, beginning with one. In this example,
assume that the FP-TC-120 is the first module connected to the FP-3000.
Therefore, set the value of
FIELDPOINT_MODULE to 1. Since the
thermocouple is wired to the terminals associated with channel zero on
the module, set the
FIELDPOINT_CHANNEL parameter to 0.