Multiple Projects
You can open up to eight TIA Portal instances in parallel — across TIA Portal versions V15…V21; multiple instances of the same version are allowed, only the total of eight is capped. Each open instance runs its own isolated TIA Portal session, so a crash in one does not affect the others. One instance is active at a time; the Project Explorer and the rest of the workspace always reflect the active instance, and you switch the active instance from the Project Explorer header or the status bar.
Switching projects from the Project Explorer header
As soon as a project is open, the Project Explorer header shows the active project's name with a small arrow next to it. Click the name (or press Enter while it has keyboard focus) to open a list of every connected project — the active one is marked with a check. Pick a different project and the Project Explorer switches to it immediately. A project whose contents are still being read is marked (loading…) in the list — you can switch to it anyway; the Project Explorer then shows a loading indicator until its tree is ready.
Below the project list, Add Project… opens another project alongside the current ones. At the eight-project limit the entry is greyed out — close a project first.
With no project open, the header simply reads "Project Explorer" and clicking it folds the view as usual.
Switching instances from the status bar
The TIA entry at the left of the status bar (very bottom of the window) shows the active instance — the TIA Portal version and project name, with a trailing count such as (3) when more than one instance is open.
When more than one instance is open, click that status-bar entry to open the instance switcher — a picker that lists every open instance (the active one marked with a check) plus an Open / Attach New Instance entry. Selecting an instance makes it active and reloads the Project Explorer for that instance's project.
The Project Explorer always shows the active instance's project. Tree expansion, scroll position and selection are kept per instance — switching back to a previously-active instance restores the tree exactly as you left it.
Opening another instance
The most direct way is the plus button (+) in the Project Explorer view title — it appears as soon as a connection exists. Clicking it opens a menu right at the button with two entries: Attach to Running Instance… and Open TIA Project….
Alternatively, open another instance the same way you make the first connection — run Connect, then choose Attach to Running Instance or Open TIA Project. You can also click the Open / Attach New Instance entry in the status-bar instance switcher. All paths lead to the same choice:
| Choice | Action |
|---|---|
| Open TIA Project | File picker for an .ap15 … .ap21 project file. Opens a new TIA Portal session for that version. |
| Attach to Running Instance | Lists every running TIA Portal instance with an open project; pick one to attach without spawning a second TIA Portal. |
When eight instances are already open, opening or attaching another is refused with a message — close an instance first. The plus button is greyed out then; its tooltip explains that a project has to be closed first.
Switching projects
Pick a different project from the Project Explorer header dropdown or the status-bar switcher to change the active project. The Project Explorer swaps to the new project's PLCs and blocks, and views that follow the connected project reload for the newly active instance. While the new project's tree is being read, the Project Explorer shows a loading indicator. PLCSim, the Password Vault and other application-wide surfaces stay unchanged across the switch.
The Agents window offers the same switch from the top of its Project Explorer panel — the choice is shared, so switching in either window switches both.
Closing and saving an instance
| Command | Action |
|---|---|
| Disconnect | Closes only the active instance. The other open instances stay active. |
| Save Project | Saves the active instance's project (atomic — same behaviour as TIA Portal's Save action). |
Run these from the Command Palette (Ctrl+Shift+P); Save Project is also a button in the Project Explorer view title.
Same-version multi-instance
You can open and attach to several TIA Portal projects of the same major version in parallel — each its own isolated TIA Portal session. The total number of open instances is capped at eight, counted across all versions combined.
Connect will only refuse the action in two specific cases:
- The selected project file is already open in another instance — Connect reports that the project file is already open. Switch to the existing instance from the status bar instead.
- You picked an already-attached running TIA Portal instance from the Attach list — Connect reports that the TIA Portal instance is already attached. The same message also appears if you open a project from file (which starts a fresh TIA Portal) and then later select that same TIA Portal from the Attach list — both entry points share a single instance-per-session rule. Pick a different running instance, or switch to the existing one.
A closed or crashed TIA Portal
If the TIA Portal behind an open instance is closed or ends unexpectedly (window closed, crash, process kill, out-of-memory), Studio notices right away: the instance disappears, a notification names the disconnected project, and the status bar switches to the surviving active instance. Other open instances keep running normally — only the affected session is gone. Run Connect to reconnect at any time.