Specifying Testing Limits in TestStand

Specifying Testing Limits in TestStand

When a NI VMS step has executed the measurements performed can be evaluated for step pass/fail result. This can be configured using the NI VMS Limit Editor.

Right clicking on a NI VMS Analyser step brings up the dropdown menu shown below.

Selecting Edit Limits will open the NI VMS TestStand Limit Editor that based on the NI VMS setup of the step, contains the video parameters that will be measured when the step is executed. The limit editor panel is shown below, when the video measurement is Differential Gain and Phase (DGDP).

Pass/fail limits can be specified each of these parameters and these are written to Step.Result[x].Limits.LowLimit and Step.Result[x].Limits.HighLimit. Incl enables/disables report entry for the parameter.

Limits can be read dynamically, during runtime, from a text file. Pressing Save Dynamic File will make a text based limit file, which can be used as a skeleton to assign limits for all Measurement Results. The limit file is then being loaded dynamically at runtime, hence making it possible to test against different limits for instance, by copying the correct limit file to the name defined in Dynamic Limit File, in steps before NI VMS steps.

The measurement name, test element and results are listed in the table. A scroll bar will appear if number of results are larger than 7. For each result a minimum and maximum limit can be specified as well as an evaluation symbol can be chosen. Example:

-12.34 < Measurement <= 22.12

If no evaluation is chosen either limit values will disappear. Example:

Measurement < 22.66, same as -inf < Measurement < 22.66.

Setting lower Eval to empty (top of the list), means that no minimum limit exists.

The limit setup can be either imported or exported to file for convenience. Exporting causes a LabVIEW data log file to be created containing the limit setup as well as a header with the Measurement Name and Test Element. Upon import, the measurement name and test element has to match the current setup, otherwise an error message will pop up stating that Measurement Name and Test Element in the limit file does not match the actual setup.

Additional version information will be added to the limit file so future versions of NI VMS for NI TestStand limit handling interface can convert older limit files automatically.