Chapter 2: Operation; Front Panel Vs. Block Diagram; Visa Session In And Out - ILX Lightwave FPM-8220 User Manual

This chapter is an introduction to the LabVIEW software and the FPM-8220 Fiber Optic Power
Meter LabVIEW Instrument Driver. This chapter also includes:

Common Instrument Driver Features

FPM-8220 Sub-VI Descriptions

FPM-8220 VI Descriptions

Front Panel vs. Block Diagram

The Front Panel appears when a sub-VI is opened. The Front Panel for every sub-VI includes
VISA session IN and OUT ports, as well as error IN and OUT ports. Additionally, there are
inputs and outputs relating to the specific operation the VI.
To open the Block Diagram of the sub-VI, select Window in the toolbar of the Front Panel and
choose Show Block Diagram. The Block Diagram displays the code that communicates with
the instrument. The information required by the code appears as a labeled icon in the Block
Diagram and is input by the user on the Front Panel. The information output by the code also
appears as a labeled icon and is displayed on the Front Panel. The Front Panel and the Block
Diagram of a sub-VI are two different views of the same code.

VISA Session IN and OUT

The VISA Session box on the Front Panel provides a drop down menu of the remote addresses
available. The VISA Session OUT outputs the VISA Session address that was input to the sub-
VI. Although this seems redundant inside of the sub-VI, it creates flow between sub-VIs. See
the example below.
Figure 1: Three sub-VIs without VISA Session IN/OUT are controlling the same instrument.
Figure 2: Three sub-VIs with VISA Session IN/OUT are controlling the same instrument. The VISA Sessions OUT
July 2011
make it possible to input the address once and reduce the clutter.
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Chapter 2:
Operation
FPM-8220 LabVIEW Manual