Python串口发送文件至电能表遇XMODEM报错求助

Hey there! Let's break down what's going wrong here and fix it step by step.

The Root Cause #

That error AttributeError: 'str' object has no attribute 'read' is happening because your ser variable is just a string containing the port name (like "COM3"), not an actual opened serial port object. When you call ser.read() in your getc function, Python tries to run a read() method on a string, which doesn't exist—hence the error.

The Fix #

You need to initialize a proper serial port connection using serial.Serial() from the pyserial library first, instead of just storing the port name as a string. Here's the corrected code with explanations:

import serial
from xmodem import XMODEM

# Extract the port name from your combobox (this part was okay)
port_name = serialPortCombobox.get().split(" ")[0]

# Initialize the serial port with parameters matching your electricity meter
# Adjust baudrate, parity, etc. to match your device's specs!
ser = serial.Serial(
    port=port_name,
    baudrate=9600,  # Replace with your meter's actual baud rate
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS,
    timeout=1
)

def getc(size, timeout=1):
    ser.timeout = timeout
    # Now ser is a real serial object, so read() works as expected
    return ser.read(size) or None

def putc(data, timeout=1):
    ser.timeout = timeout
    return ser.write(data)

modem = XMODEM(getc, putc)

# Use try/finally to ensure we clean up resources even if an error occurs
try:
    # Use 'with' to auto-close the file after transfer completes
    with open('105.8k', 'rb') as f:
        status = modem.send(f, retry=3)
        print(f"XMODEM transfer status: {status}")
finally:
    # Always close the serial port to avoid resource leaks
    ser.close()
    # stream.close()  # Remove this line if 'stream' isn't defined in your code

Key Notes to Remember #

• Match Serial Parameters: Double-check that baudrate, parity, stopbits, and bytesize exactly match the specifications of your electricity meter. If these are incorrect, the transfer will fail even after fixing the initial error.
• Resource Management: Using with for the file and try/finally for the serial port ensures you don't leave files or ports open accidentally if something goes wrong mid-transfer.
• Check Dependencies: Make sure you have pyserial installed (pip install pyserial) since it's required for serial communication.

内容的提问来源于stack exchange，提问作者Shay Avitapl