Gnu Octave to Labview Pipes Interface
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README.md

README.md

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Gnu Octave to Labview Pipes Interface

Try GNU Octave in LabVIEW with a new shiny interface!

LabVIEW can do some very limited mathematics. Therefore one has to use an external software. LabVIEW provides easy connection to e.g. Matlab, however Matlab is not free, so if you want to make a measurement program and use it on many computers, you need multiple licences or expensive server licence.

Or you can use GNU Octave - open source and free software with almost the same syntax as Matlab, and similar capabilities and speed. Unfortunately GNU Octave is not directly supported by LabVIEW. In Linux, you can use comfortable pipes to interface GNU Octave. For unknown reasons Windows pipes are still missing in LabVIEW. Some old pipes implementation exist but not really working in new LabVIEW versions. So GOLPI (Gnu Octave to Labview Pipes Interace) was created.

GOLPI works as a device. You initialize it, sends values or commands into, reads variables or outputs, repeat as you like, when you finished you quit it.

Features:

  • Pipes (stdin and stdout) are used for communication to and from GNU Octave.
  • Polymorphic VI for reading a value of a variable (by means of stdout or temporary file for large amount of data).
  • Polymorphic VI for seting a value to a variable (by means of stdout or temporary file for large amount of data).
  • Reading and setting works also for structures (GNU Octave) from/to clusters (LabVIEW) (requires golpi package for GNU Octave).
  • Can check if GNU Octave is still running.
  • Debug mode can store all communication going through pipes.
  • Debug console can be shown to view ongoing communication.
  • 4 examples included.
  • Tested on several versions of GNU Octave in Windows.
  • 3 different methods to transfer data form/to GNU Octave: normal method use using stdin/stdout, temporary file method use file with mat4 format, bitstream method using optimized stdin/stdout. For comparisons see examples.
  • From version 0.7, GOLPI can also communicate with Matlab (based on popular request of our partners)

Four components:

  • lv_process: C++ library which handles pipes.
  • LV Process: LabVIEW interface for lv_process
  • GOLPI: starts GNU Octave, send commands, read commands etc.
  • golpi: GNU Octave package with utilities for fast data transfer GNU Octave <-> LabVIEW and for transfer of GNU Octave structures from/to LabVIEW clusters (optional).

1, lv_process

Dynamic-link library. This library was developed for pipe communication with console application. It is basically just a wrapper for nasty WINAPIs dedicated for pipe handling and process execution. The wrapper simplifies the whole operation to just a several functions with simple data types. The lv_process.dll has to be present for use of LV Process and GOLPI in LabVIEW.

2, LV Process

LabVIEW library. Yet another implementation of pipes in LabVIEW for Windows operating system. (OpenG implementation seems to be abandoned). VIs call lv_process.dll to start a process, send and receive data through stdin and stdout, closes process. Pipe is in fact cluster containing handlers and setting. User can change the cluster values as required (be careful). All traffic can be logged if debug mode is started. Debug console can be shown on the background.

It can be simply used as standalone (without GOLPI).

3, GOLPI

LabVIEW library. GOLPI use LV Process and lv_process.dll to start/quit GNU Octave, send and receive data to/from it and send commands.

4, golpi

GNU Octave package. It contains two functions:

  • golpi_data2bits - used for Bitstream transfer mode in GOLPI.
  • golpi_conv_struct - used for structure to cluster transfer in GOLPI.

GOLPI Examples

Block diagram of the VI Tree:

GOLPI VI Tree

Block diagram of very simple demonstration:

GOLPI block diagram

Download

Installation & use

Download packed library or all source codes. Copy into your LabVIEW project. Put lv_proc.dll into the root directory of your project.

License

GOLPI, LV Process and LV Process dll is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 3.

GOLPI, LV Process and LV Process dll is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with GOLPI, LV Process and LV Process dll. If not, see http://www.gnu.org/licenses/.