Why Are Some Serial Port Values Displaying as Question Marks?

Your serial port code initializes the port and sets up event handlers for data reception and error handling. It also includes a data transmission method. The appearance of question marks in the output suggests a problem with data interpretation or transmission.

Here's a breakdown of troubleshooting steps to resolve the question mark issue:

1. Verify Serial Port Configuration: Double-check that your code's serial port settings (baud rate, data bits, parity, stop bits) precisely match the device's configuration. Even a minor mismatch will lead to garbled data.

2. Inspect Physical Connections: Carefully examine all physical connections between your computer's serial port and the device. Ensure cables are securely connected at both ends, and that the device is properly powered on.

3. Test with Alternate Ports and Cables: Try using a different serial port on your computer and a different USB cable (if applicable). This helps isolate potential hardware issues.

4. Update Serial Port Drivers: Outdated or corrupted drivers can cause communication problems. Update your serial port drivers to the latest versions available from the manufacturer.

5. Test on Another Computer: Connect the device to a different computer to rule out any problems specific to your current system.

6. Investigate Power Supply (if applicable): If you're using a USB-to-serial converter, insufficient power might be the culprit. As seen in a similar Stack Overflow thread (link provided), using a powered USB hub can resolve this.

If these steps don't solve the problem, the device's serial port itself may be faulty.

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