Variant to XML

-

Converting to XML format is a good way of exporting data in a standard, human-readable way. I have used it to pass and receive data from other languages, for example, or if you need to dump data to a log file.

As you may know, LabVIEW includes its own functions for converting to and from XML, called Flatten To XML and Unflatten From XML. Unfortunately, it's a raw conversion that just gives a node with the data type and two child nodes, name and value. So, to find a field you must recover first all the name nodes, locate the one you need and then find its value sibling. Too crude for a lot of scenarios:

So I developed my own library to do this conversion in a more convenient way. Check the differences in the next image:

As you can see the field names are now used as tag names, resulting in a shorter and cleaner XML text. The reverse conversion (from XML to LabVIEW data) is shown in the bottom of the image, and works the same.

In the block diagram, these functions are used directly, just transform the resulting variant to the specific data type, as shown:

Remember to be careful with field names, don't use strange characters or spaces as that can conflict with XML guides. I also added an URL encoded option, useful when transmitting data over the net.

Download Variant to XML (LLB for LabVIEW 2016)

Of course, I haven't covered all possible data types, just the ones I use, so maybe you'll need to edit my code and add your own; go ahead, it's easy. Currently the library accepts integers (all types), enums, float (single and double), string, path, waveforms, and arrays and clusters composed of those data types. Variant attributes are exported as tag attributes, a good way to include additional info on your XML.

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