Programming

A practical example of compiler optimization side effects: when the volatile keyword becomes essential

Second post about LabVIEW and Rust. This time we will pass native LabVIEW array into DLL written in Rust and resize inside.

Finally wrote command line script to build open62541 library automatically (more or less).

For some reason, I need a fast method for string search. The LabVIEW Search/Split String function is relatively slow, I’ve done this using String Zilla, and achieved around a 20x boost with AVX2/AVX512.

I just encountered slow string performance in LabVIEW when a large string is passed to a DLL as a C string pointer. It is always better to pass it as ‘Adapt to Type’ instead of a pointer.

By default its limited, but can be manually increased in LabVIEW.ini

ParallelLoop.MaxNumLoopInstances=256

B&R PLC could be programmed with C and C++. But you can also use Assembly. Below short instruction how to do that.

B&R PLC could be programmed with C++. State Machine is common used pattern. There are lot of examples of how to implement State Machines in C++. One of the example was taken and turned to B&R State Machine

It is a very funny fact that the NI’S Web Site doesn’t support NI’s Snippets properly, especially on NI Forum, where the Snippets used actively to exchange the small pieces of the LabVIEW code. Here how you can get code from such snippets.

In some cases we need to measure a very short intervals (hundreds of the CPU Tacts) directly in Assembler. We can perform measurement by using cpuid/rdtsc combination.

Collection of useful small Snippets

A very simple and basic TCP communication example for Python and LabVIEW

Interesting question was raised on NI Forum. “I have created an app that works without issue… As a DLL called by Python, 1 of the functions work… the other just freezes.”. The reason is — the Execution System was set “same as caller” (which is default), but Python is not LabVIEW.

In this “weekend” experiment I’ll write large file (16 GB in my case), then read it back with different buffer size and threads and check the performance.

Nowadays development on pure Assembler is not very popular, because modern compilers can generate “good” code. On the other hand this is a very good exercise, which helps to understand a calling conventions and how it work in very low details.