labview parameter ranges in teststand

[Guzz]

in teststand is it possible to have the parameters of a specified labview vi (setup in the "Edit LabVIEW VI Call" panel) to automatically use the ranges specified within the labview vi front panel at step generation rather than at step run time?

eg. a U32 parameter on the vi panel with a data range of 1 to 20 - automatically limiting the allowed range of values within the testset action step

also....i've assigned a help file (generated from the labwindows fp file) to the labview vi but am not able to access this via teststand (using the VI Help button on the "Edit LabVIEW VI Call" panel) - i get a popup saying help is not available, run setup to install it.

[JoseHdz]

Guzz,
It is not possible to use the ranges specified in a LabVIEW control. You will have to check for the range yourself in TestStand.

About the help file, can you open the help file from LabVIEW?

Regards,
Jose

[Guzz]

not possible????
that seems to be a bit of an ommission!! we were under the impression that labview was very closly tied to teststand (half eason we've not used the labwindows code directly) - to have the ability to setup the default values in teststand, as defined in labview, but not apply range checking seems a little odd.

as for the help file, yeep...not a problem in labview (help menu, "help for this vi") it finds the help straightaway

also i notice that teststand can display the "context help" for the vi as a whole but for each parameter (the context help was auto generated when building the LLB from the labwindows FP file) - is there any reason why individual parameters cannot have tips visible in teststand?

[Dennis_Knutson]

LabVIEW itself doesn't check the default values. There is nothing to prevent you from dropping your VI into another a VI and wiring a control or constant to the input and passing a value that is outside the range you specified. LabVIEW will coerce the input to the range you specified but you have no way of knowing that the coercion was done. The same is true when you write a function in CVI or other languages. Instead of defining the range of a control with the Data Range option, it is better to use the In Range and Coerce function on the Comparison palette. Then, when an invalid input is passed, you will know by the coerce output and generate an error.

[Guzz]

what exactly is the point of the data range option in the labview vi then?
having the input coerced or ignored isnt the most useful...what about error?????

adding extra functionality to all the VIs (wrappers to the real code in labwindows) to range check against hard coded ranges within a vi doesnt seem the most tidy way of doing things.

we are already performing range checks on input parameters when it gets all the way down to the real code in labwindows, we were rather hoping that the VI to teststand interface would afford us some level of edit time range checks instead of having to wait till runtime (to ensure the scripts are valid)

[Dennis_Knutson]

I agree that it isn't all that useful except when you are designing a GUI. Having an error option would be a great suggestion for a new feature in LabVIEW. The way that I write TestStand sequences is with custom step types for everything. They all have an edit step written in LabVIEW. This GUI then enforces the range of parameters that can be passed to the actual step. That way, the sequence doesn't even have to be run to generate an error. The user gets immediate feedback as soon as an invalid parameter is entered.