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  • Author Author: mvalencia32
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Wilcoxon PC420V vibration sensor with a Raspberry Pi 5

mvalencia32
Wilcoxon PC420V vibration sensor with a Raspberry Pi 5

Vibration analysis is important for any industrial process, as it provides us with a lot of information about the mechanical state of the machines we use. It also allows us to use their signals as interlocks in PLC programming, etc. Therefore, one of my motivations for creating this small blog was to use a Wilcoxon sensor and adapt it to a Raspberry Pi with the idea of being able to view RMS measurements on the screen and log them in a .csv file.

Table of specifications:

Parameter Specification
Sensitivity 100 mV/g
Measurement Range 0 to 0.5 ips (inches per second)
Frequency Response 2.5 to 15,000 Hz (±3 dB)
Resonance Frequency >25 kHz
Transverse Sensitivity <5%
Power Requirement 18-30 VDC
Output Signal 4-20 mA
Operating Temperature -40 to 85 °C
Case Material Stainless Steel
Weight 145 grams (5.1 oz)
Mounting 1/4-28 UNF
Connector 2-pin MIL-C-5015

Pics:

Image 1; 

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Project Comments:

  1. The Raspberry Pi 5 does not have an ADC, so I had to adapt an ADS1115 (I2C), which has a 16-bit ADC. (Image 2)
  2. The Wilcoxon sensor operates at 12 volts and has a current output of 4 to 20mA. Its datasheet provides a diagram of how to integrate it with a PLC, and using that idea, it is possible to integrate it with the Raspberry Pi 5. (Image 3)

Image 2

image

Image 3

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Before processing the vibration signal, calibration tests were conducted between the ADS1115 and a reliable multimeter.

imageimage

Example Code to Anaconda Rsbaerry pi5:

import time
import math
import csv
import Adafruit_ADS1x15
import tkinter as tk
from matplotlib.figure import Figure
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

adc = Adafruit_ADS1x15.ADS1115(address=0x48, busnum=1)
GAIN = 1
DATA_RATE = 860
V_REF = 4.096
MAX_ADC_VALUE = 32767
RESISTANCE = 120

root = tk.Tk()
root.title("Lectura del ADC ADS1115")
root.geometry("800x600")
root.attributes('-fullscreen', True)

speed_label = tk.Label(root, text="Velocidad (mm/s):", font=('Helvetica', 16))
speed_label.pack(pady=10)

fig = Figure(figsize=(8, 6), dpi=100)
ax = fig.add_subplot(111)
ax.set_title("Tendencia de la Velocidad")
ax.set_xlabel("Tiempo (s)")
ax.set_ylabel("Velocidad (mm/s)")
ax.set_ylim(0, 12)
line, = ax.plot([], [], 'b-')

canvas = FigureCanvasTkAgg(fig, master=root)
canvas.get_tk_widget().pack(fill=tk.BOTH, expand=True)

speed_values = []
time_values = []

start_time = time.time()

csv_file = open('vibration_data.csv', 'w', newline='')
csv_writer = csv.writer(csv_file, delimiter=';')
csv_writer.writerow(['Timestamp', 'Speed (mm/s)'])

def calculate_rms(voltage_values):
square_sum = sum(v ** 2 for v in voltage_values)
rms = math.sqrt(square_sum / len(voltage_values))
return rms

def current_to_speed(current_ma):
if current_ma < 4:
return 0
elif current_ma > 20:
return 12
else:
return ((current_ma - 4) / 16) * 12

def update_values():
voltage_samples = []

for _ in range(86):
adc_value = adc.read_adc(0, gain=GAIN, data_rate=DATA_RATE)
voltage = (adc_value / MAX_ADC_VALUE) * V_REF
voltage_samples.append(voltage)
time.sleep(1 / DATA_RATE)

rms_voltage = calculate_rms(voltage_samples)

current_ma = (rms_voltage / RESISTANCE) * 1000

speed_mm_sec = current_to_speed(current_ma)

speed_label.config(text=f"Velocidad (mm/s): {speed_mm_sec:.6f}")

current_time = time.time() - start_time
speed_values.append(speed_mm_sec)
time_values.append(current_time)

csv_writer.writerow([current_time, speed_mm_sec])

if len(speed_values) > 100:
speed_values.pop(0)
time_values.pop(0)

line.set_data(time_values, speed_values)
ax.set_xlim(min(time_values), max(time_values))
canvas.draw()

root.after(100, update_values)

update_values()
root.mainloop()
csv_file.close()

Results:

Image 2

image

Rasberry Pi Screen:

image

I hope you found this blog entertaining.

Regards

Martin