NI VMS for NI TestStand Adjustment Loop Controller Utility

NI VMS for NI TestStand Adjustment Loop Controller Utility

Introduction

This document describes how to use the NI TestStand Post Scale Corrections custom step type.

This custom step type is used to perform a calibration of individual NI VMS measurement parameters based on readings from a known signal source.

The calibration is performed by applying an external video signal generator with known video parameters. A calibration is first performed against this known signal source and scaling information is stored in an external text file. After this, NI VMS readings are scaled using these calibration coefficients.

Additionally an editor is included to make or modify the calibration coefficients file.

Related and required software

NI VMS for NI TestStand

How to use the NI TestStand Adjustment Loop Controller Step Type

The NI TestStand Sequence Control Step Type components have to be used correctly in order to get the right functionality. The NI TestStand sequence is jumping to the step name stored in a runtime created local variable called Locals.Destination. This variable contains at start the first enabled NI VMS step but is being changed if either Continue or Abort on the Adjustment Loop Controller panel is pressed. When a button is pressed Locals.Destination is either set to the step after the Adjustment Loop Controller step or the first step in the CleanUp Step Group hence breaking the Adjustment Loop.

Therefore it is important that the wanted NI VMS steps are included in the NI TestStand sequence prior to adding and configuring the Adjustment Loop Controller. So first you will create a sequence file with the necessary NI VMS steps with configured pass fail limits for parameters and after this add the Adjustment Loop Controller step after the last NI VMS step that must be included in the Adjustment Loop, (see Figure 1).

Important usage information

Due to the way the Adjustment Loop Controller panel works it is important NOT to break execution when the Adjustment Loop Controller panel is popped up. This LabVIEW is a modal LabVIEW dialog with respect to NI TestStand; therefore the user has lost NI TestStand user interface control while the Adjustment Loop Controller panel is open.

User Interface

There are two setup panels included with this step type. Each of these is discussed in detail in the following chapters:

• Adjustment Loop Controller Panel
• Configure Adjustment Loop Controller

Adjustment Loop Controller Panel

The Adjustment Loop Controller panel (see Figure 2) will pop up during NI TestStand execution when reaching the Adjustment Loop controller step and stay up until either Continue or Abort is pressed.

The number of visible parameters is limited to 7, but if more than 7 are included a scrollbar will appear and enable the user to scroll through the enabled parameters during sequence execution.

Figure 2: Adjustment Loop Controller panel

Adjustment Loop Controller Panel controls

Table 1: Horizontal Bars Display Setup controls

User interface control

Relations of values between dependant controls on the user interface:

Table 2: User interface control

Configure Adjustment Loop Controller

Setup panel is used to configure the Adjustment Loop Controller. All the prior NI VMS steps in the given step group relative to the Adjustment Loop Controller step is listed in the left tree control. Each of the parameters can be either included or excluded from the runtime Adjustment Loop Controller panel by double clicking on it (see Figure 3).

Figure 3: Configure Adjustment Loop Controller Panel

Selecting a parameter in the left tree control allows the user to see the Measurement, Parameter, Low Limit, last measured Parameter Value, High Limit and Unit. The low and high scale values can be configured by hand or automatically calculated as +/- 10% of the limit span. Default when inserting a new NI VMS step the scale values are calculated as +/- 10% of the limit span.

Double-clicking on a parameter in the NI VMS Steps tree control will toggle inclusion as well as selecting the NI VMS step.

This step type is used to configure the runtime sequence control panel. Enabled buttons available, their look, key navigation, the NI VMS step that will be executed and finally the position of the control panel on the screen, are configured through this interface.

Controls available on front panel

The following controls are available on the Configure Adjustment Loop Controller panel

Table 3: Configure Adjustment Loop Controller controls

User interface control

Relations of values between dependant controls on the user interface:

Table 4: Configure Adjustment Loop Controller user interface control

Returned values to NI TestStand

No results are being passed back to NI TestStand by the Adjustment Loop Controller types except the normal Result container. Refer to the NI VMS for NI TestStand Interface section for the NI VMS results returned.

Error handling

Warnings

Warnings and system errors that occurs during configuration (setup) mode are shown in a pop up message. From this message the user can select to stay in configuration mode or exit. In Run mode the pop-up messages is never shown.

System errors

System errors are always returned in the error container except in setup mode (see previous section).

Examples

Refer to the NI Video Measurement Suite Readme for the location of TestStand sequence example(s) for this utility.

• AdjustmentLoopController Demo1.seq demonstrates a single adjustment loop in one sequence.
• AdjustmentLoopController Demo2.seq demonstrates two cascaded adjustment loops in one sequence. One has the popup panel free, the next popup panel is in a locked screen position.
• Multiple Cascaded Adjustment Loops Demo1.seq calls the two examples as subsequence calls.