Difference between Active and Passive Transducer

 

Feature	Active Transducers	Passive Transducers
Power Supply	Requires an external power source to operate	Does not require an external power source
Energy Conversion	Converts physical quantities directly into electrical signals	Converts physical quantities into a change in non-electrical form (e.g., resistance)
Output Signal	Direct electrical signal (voltage or current)	Change in resistance, capacitance, or inductance (needs external circuit to measure)
Signal Processing	Signal can be read directly, no need for complex circuitry	Requires external circuits (e.g., bridge circuits) to process the signal
Examples	Thermocouples, Piezoelectric sensors, Photovoltaic cells	Strain gauges, Thermistors, LVDTs

Absorptive and Reflective RF switches: Introduction and comparison

Understanding Absorptive and Reflective RF Switches: A Deep Dive into RF Switching Technology

In the world of Radio Frequency (RF) technology, switches play a crucial role in controlling signal flow between different circuits. RF switches are integral components in a wide range of applications, from wireless communication systems to radar and satellite systems. Among the various types of RF switches, absorptive and reflective RF switches are two of the most common, each with distinct characteristics and use cases.

In this blog, we’ll explore what absorptive and reflective RF switches are, how they work, and where each type is best suited.

What Are RF Switches?

An RF switch is a device used to route high-frequency signals from one transmission line to another. Essentially, it acts as a gatekeeper, controlling which path the RF signal will take in a circuit. This functionality is essential in applications where signals need to be selectively sent to different receivers, antennas, or testing equipment.

RF switches can be designed using different technologies such as PIN diodes, field-effect transistors (FETs), and micro-electromechanical systems (MEMS), depending on the specific needs of the application in terms of speed, power, and frequency.

The Difference Between Absorptive and Reflective RF Switches

The primary distinction between absorptive and reflective RF switches lies in how they handle the signal on the ports that are not selected (i.e., the "off" ports). Let’s take a closer look at each type.

Absorptive RF Switches

An absorptive RF switch (also called a terminated switch) is designed to present a matched impedance (typically 50 ohms) to all of its ports, regardless of whether the port is active (connected) or inactive (disconnected). When a signal is routed through one path, the other paths are terminated with matched loads to prevent signal reflection and standing waves.

How Absorptive Switches Work:

- When a port is not selected, the switch routes the signal to a termination (typically an internal 50-ohm resistor).

- This absorption of the signal into a matched load prevents any signal from being reflected back into the circuit.

- By terminating inactive paths, the switch ensures that there is minimal interference or signal distortion, making it ideal for sensitive RF systems.

Applications:

Absorptive RF switches are preferred in systems where signal integrity is critical, and reflections or standing waves could cause performance degradation. They are often used in:

- Test and measurement equipment

- Communication systems requiring high precision

- RF signal routing in sensitive environments like radar and satellite communications

Reflective RF Switches

A reflective RF switch, on the other hand, does not provide matched impedance on its inactive ports. Instead, when a port is not selected, the signal is reflected back into the circuit. The inactive ports are left open or short-circuited, which causes signal reflections rather than termination.

How Reflective Switches Work:

- When a port is not selected, it remains disconnected without any termination.

- The signal that hits the inactive port is reflected back into the circuit.

- These reflections can sometimes interfere with the active signal path, depending on the system design and the level of isolation between ports.

Applications:

Reflective RF switches are commonly used in applications where reflections are either acceptable or can be managed by the overall system design. They are particularly useful in:

- RF power switching where high levels of power are present

- Systems where cost and simplicity are more important than minimizing signal reflections

- Antenna selection switches, where reflections may not be critical

Key Differences Between Absorptive and Reflective Switches

Feature	Absorptive RF Switch	Reflective RF Switch
Impedance Matching	Provides matched impedance (usually 50 ohms) on all ports	Only the active path is impedance matched; inactive ports reflect signals
Signal Handling on Inactive Ports	Terminates signals to a matched load	Reflects signals back into the circuit
Performance Impact	Reduces reflections, minimizes interference, and maintains signal integrity	May cause signal reflections, potentially leading to interference
Typical Applications	Test and measurement equipment, precision communication systems, radar systems	High-power applications, antenna switching, systems where reflections are acceptable

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Choosing the Right Switch for Your Application

The decision to use an absorptive or reflective RF switch depends on the specific needs of the application. If your system is highly sensitive to signal reflections and requires precise signal integrity, an absorptive switch is likely the better choice. This is especially true in test environments and high-performance communication systems where even small amounts of signal distortion could lead to significant performance issues.

On the other hand, if your application involves switching high power RF signals or if reflections won’t have a significant impact on performance, a reflective switch may be more cost-effective and simpler to implement.

Conclusion

Absorptive and reflective RF switches offer different advantages depending on the nature of your RF system. Absorptive switches are designed to minimize reflections and maintain signal integrity, making them ideal for sensitive applications. Reflective switches, on the other hand, are simpler and better suited to high-power applications where reflections can be tolerated or managed.

When selecting the right RF switch for your system, consider factors like signal integrity, power levels, cost, and system complexity. Understanding the differences between these two types of RF switches can help you make the best decision for your specific needs and ensure optimal performance of your RF circuits.

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Whether you're designing a high-precision communication system or working on a robust power-switching solution, knowing how absorptive and reflective RF switches function will give you the edge in optimizing your RF system's performance.

Multi Channel Analog data display on Python based GUI from Arduino Serial port

To create a Python Tkinter GUI that fetches many comma-separated values from a serial port and displays them we can use the pyserial library to handle the serial communication. Below is a simple example demonstrating how to achieve this. Make sure you have both tkinter and pyserial installed. You can install pyserial using pip if you haven't done so already:

The arduino code is simple modified version of available AnalogReadSerial example. In the code 4 AI channels are read and one DI channel is read. Their values are transmitted over Serial port. Note the COM port number of device and change accordingly in the code.

// the setup routine runs once when you press reset: void setup() {  // initialize serial communication at 9600 bits per second:  Serial.begin(9600); } // the loop routine runs over and over again forever: void loop() {  // read the input on analog pin 0:  int Val1 = analogRead(A0);  int Val2 = analogRead(A1);  int Val3 = analogRead(A2);  int Val4 = analogRead(A3);  bool state = digitalRead(8);  // print out the value you read:  Serial.print(Val1);  Serial.print(Val2);  Serial.print(Val3);  Serial.print(Val4);  Serial.println(state);  delay(500);        // delay in between reads for stability }

Below is the Python script.

      
import tkinter as tk
import serial

# Serial port configuration
SERIAL_PORT = 'COM3'  # Change this to your serial port
BAUD_RATE = 9600

class SerialApp:
    def __init__(self, master):
        self.master = master
        self.master.title("Serial Data Display")
        
        # Create labels for each value
        self.labels = ['Val1:', 'Val2:', 'Val3:', 'Val4:']
        self.value_labels = []

        # Configure font
        label_font = ("Helvetica", 30, "bold")
        
        # Create and place labels in grid
        for i, label in enumerate(self.labels):
            lbl = tk.Label(master, text=label, font=label_font)
            lbl.grid(row=i, column=0, padx=20, pady=10)
            value_lbl = tk.Label(master, text="", font=("Helvetica", 30))
            value_lbl.grid(row=i, column=1, padx=20, pady=10)
            self.value_labels.append(value_lbl)

        # Open serial port
        self.serial_port = serial.Serial(SERIAL_PORT, BAUD_RATE, timeout=1)

        # Update the GUI
        self.update()

    def update(self):
        try:
            # Read data from serial port
            line = self.serial_port.readline().decode('utf-8').strip()
            values = line.split(',')

            # Ensure we have four values
            if len(values) == 4:
                for value_lbl, value in zip(self.value_labels, values):
                    value_lbl.config(text=value)

        except Exception as e:
            print(f"Error: {e}")

        # Schedule the next update
        self.master.after(1000, self.update)

    def on_closing(self):
        self.serial_port.close()
        self.master.destroy()

if __name__ == "__main__":
    root = tk.Tk()
    app = SerialApp(root)

    # Handle window close event
    root.protocol("WM_DELETE_WINDOW", app.on_closing)

    root.mainloop()

The GUI will look as below

https://github.com/arihant122/Python-Tkinter-based-GUI-by-fetching-Serial-port-data-from-Arduino-

Getting Started with Codesys v3.5 and Wago PFC200 (750-8212)

 

 

Step 1: Search for Codesys v3.5 in any search engine.

Step 2: When you click on the link, it redirects you to following page. Click on the download button. It will redirect you to a new webpage with Codesys v 3.5 descriptions.

 

 

Step 3: Click on Open Page link, which open a new webpage.

Step 4: User can download the software along with dependencies as a bundle download or selecting individual dependency as per his/her requirement.

Step 5: Click on Codesys 3.5 setup file to initiate installation.

Once installation is complete, launch the Codesys to check if installation is correct.

After this, you have to install Wago Licensing, Wago Solution Builder, Wago codesys Download Server, Wago Device and Libraries which are downloaded in Step 4 as a bundle.

Step 6: Again Launch Codesys 3. Create a New Project from Basic Operations.

Create a standard project and then choose suitable Name and Location where you want to save the project file.

Once done, you have to select the Device and Programming Language from drop down menu.

          

I have selected 750-8212 as my PLC device and Ladder Logic Diagram as my programming language. You will see the device list only if Wago Device and Libraries are properly installed.

 

Selected target system is different from the connected device

Once you connect a Wago PFC 750-8212 device with PC and develop a ladder program, you will have to download the program into the PLC.

In some cases, it may display “selected target system is different from the connected device” error message. This happens due to firmware incompatibility between the codesys wago device library and PLC firmware. The user will have to update the firmware of the device in that case.

 

 

PLC Firmware update

In the softwares downloaded in Step-1, you will find Firmware also which needs to be uploaded to the PLC. The firmware can be uploaded using Wagoupload. WAGOupload is a stand-alone PC software for transferring, backing up and restoring PLC applications on WAGO 750 Series controllers.