Required Outputs Wizard

-

It's an old LabVIEW programmer's dream to be able to make VI outputs required, just as can be done with inputs. Some years ago I discovered a way of achieving it, through a deprecated scripting method. I checked with NI staff and they said it was clever but could cause unexpected problems, so I set it aside.

But the time goes by and the functionality is still not available, so here we go, the Required Outputs Wizard is yours. I've been using it on and off for a long time and no errors have arisen, even when applying it to connectors with modern data types, such as classes (OOP). But I guess the risk is still there, so be cautious and test it first with unimportant VIs.

Download (LLB for LabVIEW 2016)

The bowels of the code

So, how it works? Launch the top VI in the LLB, you can leave it there running. When a connected front panel indicator is selected, the "REQUIRED" button will be available. Just press it. Yeah, that's all, now your indicator connection is required. When you use it in another VI and leave it unwired, LabVIEW will launch an error, is quite funny:

Alright, but surely you're asking what's the trick? You can study the code by yourselves, it's pretty straightforward. The magic is in adapt vi.vi, where we get the connector type descriptor, manipulate it at bit level (cautiously, of course) and replicate it in a dummy VI. The we use the scripting SetConPane property to put it in the actual VI. Observe the red color in both connector-pane-by-typedesc functions, indicating they're deprecated.

Going deeper, in correct typdedesc.vi the essential bit is set to true:

Use in LabVIEW IDE

The standard way to add elements is well described here: Integrating into the LabVIEW Menus.

While this works good enough, now I'm thinking we could use the new shortcut menu plug-ins that became available with LabVIEW 2015 to make the process even smoother. I'll try it if I get some free time 😉.

Comentarios

Publicar un comentario

Entradas populares de este blog

SNMP library for LabVIEW

-
Imagen
SNMP (Simple Network Management Protocol) is a fairly common protocol for communicating with network equipment. It's fast, lightweight and standardized. Unfortunately it's not quite as simple as its name implies and LabVIEW doesn't support it natively. Some years ago I was in the necessity of using SNMP from a LabVIEW system to control some hardware. I started looking for already implemented solutions and found a library developed by Mark Yedinak (great work!). It was useful since it demonstrated it could be done and how, but I needed more control over the operations, so I had to read the protocol down to the low level bytes and implement what I need by myself. Yeah, pretty hard and with time constraints no less. Anyway, here it is. Download (Library in LLB file for LabVIEW 2016) See the examples folder to grasp the basic use. Probably you'll need no more than these sets of VIs to send and retrieve data and to get traps sent by your equipment. To integrate
Leer más

Base64 Encoding

-
Imagen
Long time no see! Today I'm here to talk about Base64 encoding and how to do it in LabVIEW. What is Base64 and what is used for? Base64 is a six-bit based encoding mechanism that uses only printable characters from the ASCII table (lower and upper case letters, numbers, and three more characters, usually "+/="). This means it can be represented in any textual environment, though obviously adds an overhead respect to the original code since two bits of every byte are unused. You will find B64 mainly in mail applications (to send attachments), but lately it's been popular in URLs and HTML too. The concept is to insert small chunks of data directly as B64 text to avoid recurrent callings for files through the web. For example, you can embed an image inside your HTML or CSS file. It's not my intention to delve too deep in this aspect, but for an image tag the resulting HTML code would look like this (let's assume a JPG file): <img src="data:imag
Leer más

Retrieve CPU temperature

-
Imagen
Lately I had to check the CPU temperature in a critical acquisition system, and I thought it could be a good thing to share here. I know there are several applications to do this and much more, but getting it from our code allows to react conveniently to any event. Now, IMPORTANT, the VI doesn't work on its own. First you must download the Open Hardware Monitor . Extract OpenHardwareMonitorLib.dll from the zip file and put it in the same folder the VI is located. The objects exposed in it use .NET Framework 2.0 and above, but that shouldn't be a problem in any modern machine. On the other hand, this works only for Windows , obviously. And remember, the application (either an .exe or the LabVIEW IDE) must run with administrator rights (otherwise you'll get error 1172 ). Download (VI for LabVIEW 2016) Now, if you haven't worked with .NET functions in LabVIEW, this can be a good opportunity to familiarize with them. Let's take a look at the code. First we
Leer más