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184 lines
6.6 KiB
Markdown
184 lines
6.6 KiB
Markdown
---
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title: Opening .sig files from B&K LDS shaker table machines in Python
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author: peter
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date: 2024-10-06 16:59:44 +0800
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categories: [Programming, Mechanical] # Blogging | Electronics | Programming | Mechanical | SelfHosting
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tags: [python, com, 32-bit, tip] # systems | embedded | rf | microwave | electronics | solidworks | automation | tip
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# image: assets/img/2024-10-06-Opening-sig-files-fr/preview.png
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---
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## Introduction
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Brüel & Kjær have a [line of electrodynamic shaker tables](https://www.hbkworld.com/en/products/vibration-testing/shaker-systems#!ref_bksv.com) that use their LDS Dactron signal analyzer which produce proprietary `.sig` files.
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Example of a `.sig` file's header:
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```bash
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$ xxd input1\(t\).sig | head -n 10
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00000000: 44f7 0000 0744 4143 5452 4f4e 5804 0000 D....DACTRONX...
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00000010: 0100 0000 0004 0000 0100 0000 0004 0000 ................
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00000020: 0100 0000 0100 0000 0004 0000 0969 6e70 .............inp
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00000030: 7574 3128 7429 0969 6e70 7574 3128 7429 ut1(t).input1(t)
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00000040: 0969 6e70 7574 3128 7429 0156 0156 0000 .input1(t).V.V..
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00000050: 1253 6570 7465 6d62 6572 2032 362c 2032 .September 26, 2
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00000060: 3030 3608 3130 3a35 373a 3338 0856 5055 006.10:57:38.VPU
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00000070: 2d32 3232 3200 0000 0000 0000 00a5 e2ec -2222...........
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00000080: c367 d805 3f00 0000 0000 0000 0000 0000 .g..?...........
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```
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As shown in the [user manual for their PC software](https://www.bksv.com/downloads/dactron/shakercontroller/manuals/shakercontroluserguide6.3.pdf), they provide an ActiveX Signal Reader which provides some functions to enable the `.sig` file to be opened in "Visual Basic, MATLAB, LabView, C++ and so on".
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## Tutorial on how to use in Python
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1. Download [Shaker Control](https://www.bksv.com/en/services/downloads/vibration-control-software/version-9). While a license key is required to use the software, we only need the `DactronSignal.dll` file.
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2. Install the software to a directory of your choosing, I think it installs in `C:\Program Files (x86)` by default but I am not sure since I chose to install it to `D:\Programs`. Annoyingly you do need to install the program, inspecting the installation files in 7-zip doesn't show this DLL specifically.
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3. Go to `Bruel and Kjaer\LASER and COMET Vibration Control\Shaker Control LaserUSB\bin` and copy `DactronSignal.dll` to a directory of your choosing.
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4. Create a command prompt and `cd` to the directory containing the DLL and register the DLL:
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```bat
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regsvr32 .\DactronSignal.dll
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```
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After copying the `DactronSignal.dll` file to another directory you may uninstall the program.
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The `Bruel and Kjaer\LASER and COMET Vibration Control\Signal Reader` directory contains examples for Visual C++ and MATLAB. There are also some sample `.sig` files.
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5. Create a **32-bit** Python virtual environment and activate the virtual environment OR use a **32-bit** Python installation. It must be 32-bit since the DLL is 32-bit, if you use 64-bit it will not find the class, and you will get this error:
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```powershell
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PS C:\<path>\signal_reader> python
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Python 3.9.6 (tags/v3.9.6:db3ff76, Jun 28 2021, 15:26:21) [MSC v.1929 64 bit (AMD64)] on win32
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--- ✂
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PS C:\<path>\signal_reader> python .\test.py
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--- ✂
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pywintypes.com_error: (-2147221021, 'Operation unavailable', None, None)
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During handling of the above exception, another exception occurred:
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--- ✂
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pywintypes.com_error: (-2147221164, 'Class not registered', None, None)
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PS C:\<path>\signal_reader>
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```
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6. Install `pywin32` (and `numpy` and `matplotlib` for plotting)
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```powershell
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python -m pip install pywin32
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python -m pip install numpy matplotlib
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```
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7. Create a script to see if loading the DLL works. Use the provided `FFT1(f).sig` file for testing:
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[⬇ Download `FFT1(f).sig` for testing this script](</assets/lib/2024-10-06-Opening-sig-files-fr/FFT1(f).sig>)
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```python
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import win32com.client
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import numpy as np
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import matplotlib.pyplot as plt
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dac_signal = win32com.client.Dispatch("SignalReader.DacSignal.1")
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success = dac_signal.LoadSignal("FFT1(f).sig")
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if success:
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print("Signal loaded successfully")
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else:
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print("Error loading signal")
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exit(1)
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```
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[⬇ Additional file: `G1,1(f).sig`](</assets/lib/2024-10-06-Opening-sig-files-fr/G1,1(f).sig>)\
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[⬇ Additional file: `input1(t).sig`](</assets/lib/2024-10-06-Opening-sig-files-fr/input1(t).sig>)
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8. If it loaded successfully, you may try the following script which was adapted to Python from the example MATLAB script given in the documentation `Recall_and_plot_G11.m`. This should provide the following plot:
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```python
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import win32com.client
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import numpy as np
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import matplotlib.pyplot as plt
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dac_signal = win32com.client.Dispatch("SignalReader.DacSignal.1")
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success = dac_signal.LoadSignal("FFT1(f).sig")
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if success:
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print("Signal loaded successfully")
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else:
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print("Error loading signal")
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exit(1)
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# Get slice number of the signal, for G1,1(f) signal, the value is 1.
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nSliceNum = dac_signal.NumofSlice
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# Get number of samples.
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nNumofSamples = dac_signal.NumOfSamples
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# slice index is 0 based
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indexSlice = 0
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# Sample index is 0 based
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indexFirstSmp = 0
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# Get X Begin
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xBegin = dac_signal.XaxisBegin
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# Get X Delta
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xDelta = dac_signal.XaxisDelta
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xSpacingEven = dac_signal.XaxisSpacingEven
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varX = np.zeros(nNumofSamples)
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if xSpacingEven == 1:
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# When X-axis is evenly spaced, generate values with X(i+1) = X(i) + XDelta
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varX = np.arange(xBegin, xBegin + xDelta * nNumofSamples, xDelta)
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else:
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# When X-axis is unevenly spaced, generate values with X(i+1) = X(i) * XDelta
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for i in range(nNumofSamples):
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varX[i] = xBegin * (xDelta**i)
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# Get Y data (first slice)
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varY = dac_signal.GetData(indexSlice, indexFirstSmp, nNumofSamples - 1)
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# Convert varY from a COM array to a numpy array
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varY = np.array(varY)
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# Get data type (1: real, 2: complex)
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DataType = dac_signal.DataType
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# Plot the data based on the data type
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if DataType == 1: # Real data
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plt.figure()
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plt.loglog(varX, varY)
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plt.title("Real")
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plt.xlabel("X")
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plt.ylabel("Y")
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plt.grid(True)
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plt.show()
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else: # Complex data
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varRealY = varY[::2] # Real part
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varImgY = varY[1::2] # Imaginary part
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plt.figure()
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plt.subplot(2, 1, 1)
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plt.semilogy(varX, varRealY)
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plt.title("Complex - Real Part")
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plt.xlabel("X")
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plt.ylabel("Real Part")
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plt.grid(True)
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plt.subplot(2, 1, 2)
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plt.semilogy(varX, varImgY)
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plt.title("Complex - Imaginary Part")
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plt.xlabel("X")
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plt.ylabel("Imaginary Part")
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plt.grid(True)
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plt.tight_layout()
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plt.show()
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```
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9. You may unregister the DLL after use like so if you don't trust an old dll lying around on your system.
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```bat
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regsvr32 /u .\DactronSignal.dll
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```
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