Settings: PlcTaskName dropdown is empty for Standard PLC Project (v1.18.1)

[macenc87]

Bug summary

The PlcTaskName dropdown in TwinCAT → Settings is empty even when the PLC project has a properly configured PlcTask linked to a Standard PLC Project. The dropdown does not allow free-text entry either. Clicking OK overwrites the saved value in OC.Assistant.xml with an empty string, breaking subsequent Update Project operations.

Environment

• OC.Assistant v1.18.1
• TwinCAT 3.1.4026.22 (TcXaeShell based on Visual Studio 2022)
• Windows 11
• OC_TwinCAT_Core v1.3.1, TcUnit v1.3.1
• .NET Desktop Runtime 10.0.8
• Single Standard PLC Project named TestPlc with default PlcTask (CycleTime 10 ms, Priority 20)

Reproduction

1. Create a fresh TwinCAT XAE solution with one Standard PLC Project (TestPlc).
2. Install OC_Core + TcUnit libraries; reference them in the PLC project.
3. Build the solution, activate configuration (7-day trial license active, runtime in Config mode).
4. Close TcXaeShell.
5. Open the .sln in OC.Assistant via the open button.
6. TwinCAT → Settings: PlcName dropdown correctly shows TestPlc. PlcTaskName dropdown is empty with no entries to select and does not accept typed input.

Inspection of project state

The .tsproj has the PLC properly bound (AmsPort=851) with a <Context Name="PlcTask"> linking PLC task to system task. The _Boot\TwinCAT RT (x64)\Plc\Port_851.* files exist. Build succeeds with 0 errors / 0 warnings.

Workaround

Manually editing OC.Assistant.xml to add <PlcProjectName>TestPlc</PlcProjectName> and <PlcTaskName>PlcTask</PlcTaskName> under <Twincat><Settings> works — as long as the Settings dialog is never reopened (clicking OK after that wipes the value).

Source code reference

The actual task lookup at generation time uses a direct name-based GetItem call (see OC.Assistant.Twincat/Automation/TaskGenerator.cs around the tcSysManager.GetItem(...) call), so the XML value alone is sufficient. The bug is purely in the Settings UI population of the dropdown.

Suggested fixes

1. Make the PlcTaskName combo box editable so users can type the name as a fallback.
2. Populate the dropdown directly from the <Plc><Project><Instance><Contexts><Context><Name> entries in .tsproj, which is reliable across build/activation states.
3. If the dropdown can't enumerate, preserve the existing XML value rather than clearing it on OK.

[mika-engineering]

Have you added a Task with an Image? The DropDown only lists Tasks with Image. This is intentional (see GetTasks function)

When you create the TwinCAT project via Assistant, there should be a Task with Image by default.

Sidenote:
This setting is only used when generating and linking the PLC variables to a Task. It is optional and can be used when you have a lot of variables that can be communicated faster with a single ADS Read/Write command betwenn Unity and TwinCAT. The default communication uses the ADS sum function that directly reads and writes the PLC variables without the need of the Task variables.