Arduino Opta cannot connect in PLC IDE after Manual Sketch Download (COM4 Server v12.1.0.42)

Development Tools PLC IDE
1

Environment

- Arduino Opta

- Arduino PLC IDE 1.0.8.0

- Windows 11

- Target: Opta 1.3

Issue

I cannot establish a connection between Arduino PLC IDE and Arduino Opta.

I followed the official setup and license activation guide for Opta. The Manual Sketch Download completes successfully, but PLC IDE always shows ERROR when I try to connect. Opta remains in "Please connect to the target" state and never becomes connected. Opta products are pre-licensed, so I believe the issue occurs before license activation. [1](PLC IDE and Arduino OPTA - cannot connect)[2](Opta sill not connecting to plc ide)

Steps Performed

1. Installed Arduino PLC IDE 1.0.8.0.

2. Created a completely new project.

3. Selected target "Opta 1.3".

4. Opened Opta Configuration.

5. Selected COM4.

6. Performed "Manual Sketch Download".

7. Download completed successfully.

8. Tried On-Line -> Connect.

Result

- PLC IDE status becomes ERROR.

- Opta Configuration still displays:

"Please connect to the target".

- No connection is established.

Current Modbus Configuration

- Port: COM4

- Baudrate: 38400

- Frame: N,8,1

- Address: 247

I also tested:

- Address = 1

- Baudrate = 38400

No difference.

Additional Information

- Arduino IDE 2.x can upload sketches successfully.

- Opta appears correctly as:

USB Serial Device (COM4)

- Manual Sketch Download completes successfully.

- PLC IDE runtime download appears to complete successfully.

- Cache folder was deleted:

C:\Users\\AppData\Local\T

- PLC IDE was reinstalled.

- PC was rebooted.

- A completely new PLC IDE project was created.

- The problem is still reproducible.

COM4 Server Behavior

After running Manual Sketch Download, a window appears:

COM4 Server v12.1.0.42

with:

- Users connected = 1

The unusual behavior is:

- Pressing OK does not close the COM4 Server window.

- Sometimes PLC IDE freezes when opening On-Line communication settings.

- The COM4 Server process often needs to be terminated from Task Manager.

Diagnostics

COM4 Server diagnostics show:

- TX Bytes = 0

- RX Bytes = 0

Questions

1. Is this a known issue with PLC IDE 1.0.8.0?

2. Is COM4 the correct communication port for Opta after Manual Sketch Download?

3. Is there any additional runtime installation or initialization step required?

4. Has anyone experienced a non-closing COM4 Server window together with Connect -> ERROR?

2

Solved.

The issue was not related to the COM port, PLC IDE installation, or Manual Sketch Download itself.

I followed the Arduino Help Center article:

"Reset the flash memory on STM32H747-based devices"

and ran the QSPIFormat sketch from Arduino IDE.

Steps:

1. Upload QSPIFormat.ino to the Opta.

2. Open Serial Monitor.

3. Answer Y to all prompts.

4. Wait until:

"QSPI Flash formatted!"

5. Reboot the Opta.

6. Run Manual Sketch Download again from PLC IDE.

7. Configure COM4 in Modbus communication settings.

8. Connect.

After reformatting the QSPI flash and reinstalling the PLC runtime, PLC IDE successfully connected and the status changed to CONNECTED.

Before the fix I had:

- Manual Sketch Download succeeded

- Arduino IDE uploads worked

- Connect always failed

- "Please connect to the target"

- COM4 Server issues

- TX=0 RX=0

After the QSPIFormat procedure the problem was resolved.