Handling Hexadecimal Characters in Serial Communication with Python

What will you learn?

In this tutorial, you will learn how to effectively manage hexadecimal characters during serial communication in Python. You’ll understand the significance of handling hex characters when interacting with devices over serial ports and developing hardware interfaces.

Introduction to the Problem and Solution

Serial communication serves as a fundamental method for data exchange between computers and peripherals. It often involves transmitting data that includes hexadecimal (hex) characters representing binary data in a readable format. To handle these hex characters accurately, one must comprehend the workings of Python’s serial library and adhere to best practices for encoding and decoding hex strings.

Our objective is to present a comprehensive solution for managing hex characters within serial.Serial operations in Python. We’ll initiate a connection to a serial port, send hex-encoded data efficiently, and ensure seamless reception of such data. This approach guarantees the preservation of binary data integrity throughout the transmission process while leveraging Python’s capabilities to enhance code efficiency and readability.


import serial

# Establishing connection to the serial port
ser = serial.Serial('COM3', 9600) # Replace 'COM3' with your actual port name

# Sending hexadecimal data
hex_data_to_send = "ABCD"  # Example hexadecimal string
bytes_to_send = bytes.fromhex(hex_data_to_send)

# Receiving hexadecimal data 
incoming_bytes = ser.read(size=4)  # Adjust 'size' based on expected response length
received_hex_data = incoming_bytes.hex().upper()
print(f"Received Hex Data: {received_hex_data}")

# Closing the connection 

# Copyright PHD


The provided code snippet demonstrates how to send and receive hexadecimal data using Python’s serial library:

  • Establishing Connection: Create an instance of serial.Serial, specifying the port name (‘COM3’) and baud rate (9600).
  • Sending Hex Data: Convert the hex string (“ABCD”) into bytes using bytes.fromhex() before sending.
  • Receiving Hex Data: Read incoming bytes from the serial port, convert them back into a hex string for readability.
  • Closing Connection: Properly close the connection after completing communications.

This method ensures accurate handling of hex characters during both transmission and reception processes.

  1. How do I install the PySerial library?

  2. To install PySerial, use pip install pyserial.

  3. What does .fromhex() do?

  4. .fromhex() converts a string of hexadecimal digits into its corresponding byte representation.

  5. How do I choose the correct COM port?

  6. Identify the correct COM port by checking your system’s device manager or equivalent settings panel where connected devices are listed.

  7. Can I use this approach for any baud rate?

  8. Yes, but ensure it aligns with your device’s communication speed requirements.

  9. How can I read until an end-of-line character instead of fixed-size?

  10. Use ser.readline() if expecting line-oriented input terminated with newline characters instead of specifying a fixed size.

  11. Is there error handling in case no device is connected?

  12. Implement try-except blocks around operations that may fail due to no device being connected or incorrect configurations.

  13. Can I communicate with multiple devices simultaneously?

  14. Yes, by creating multiple instances of serial.Serial, each configured for different ports/devices.

  15. What about converting integers directly into hex before sending?

  16. You can utilize {value:x} format syntax or functions like format(value,’x’).

  17. Do received messages need processing besides conversion from bytes?

  18. Depending on protocol/application requirements, additional parsing/interpretation based on known structure/format might be necessary.

  19. What other methods exist within PySerial worth exploring?

  20. Methods like .flushInput(), .flushOutput(), .in_waiting, etc., offer additional control over buffering & flow management.


Efficiently managing hexadecimal characters in serial communications enhances interactions between software applications developed in Python and external hardware devices. Mastering encoding before transmission and precise decoding upon reception enables reliable systems capable of intricate hardware-software interactions.

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