National Instruments FieldPoint FP-1600 User Manual page 39

Network module

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Do not put more than one FP Advise VI in a loop. All VIs in a loop execute only

Note

once each time a loop runs, and FP Advise VIs only complete at their advise rate. If you

had more than one FP Advise VI in the loop, the loop (and therefore all of the FP Advise

VIs in the loop) would only execute at the slowest rate of the Advises. The loop might not

execute at all if any of the advises is set to complete "On Data Change", and the data of the

corresponding I/O Item never changed.

Note

This example reads the value of an I/O Item value from the FieldPoint device. To

write to an Output Item, use FP Write instead of FP Advise (or FP Read).

A simple FieldPoint application to read an I/O Item might only need to use

four of the VIs. To create an example of such an application, complete the

following steps and refer to Figure 3-9. This application reads the inputs

from the I/O Item named All, shown in Figure 3-3.

Use FP Open to open the server. By default, the server opens with the

configuration file you last saved with FieldPoint Explorer.

Use FP Create Tag to create a handle to an I/O Item that you defined

in FieldPoint Explorer. You provide three string names to this VI to

indicate which I/O Item you want access to. These three strings are

the names given to the communications resource, the device, and the

I/O Item. Figure 3-9 shows default names as they appear when you use

the Find Devices button in FieldPoint Explorer.

Use FP Advise to continuously monitor the I/O Item at the rate

specified in FieldPoint Explorer. (You can also set a new rate with this

VI.) In this example, the while loop executes at this advise rate. If you

used FP Read VI here instead of FP Advise, the loop would free-run at

the fastest rate it could sustain, reading the I/O Item over the serial port

each time the loop ran.

Use FP Close to close the server. This action also stops all pending

advise operations.

Chapter 3

3-17

Hardware and Software Configuration

FieldPoint FP-1600 User Manual

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