# Station Control

URL: https://irs.systems/en/docs/ltt/documentation/ltt-gui-manual/lttgui/stationcontrol

A valid test station can be

* started
* stopped
* terminated
* aborted

A test station is valid if it has a completely configured [test order](Dialogs/F11testconfiguration/).

You can choose to start the currently selected test station (F1) or all valid test stations at once (F7).

You can issue a **stop request** for the currently selected test station (F1) or all running test stations at once (F8).

> By issuing a **stop request**, it depends on the TestStand sequence file if, when and how the test actually stops. This is determined by the use of the [Check For Stop](/en/docs/ltt/documentation/ltt-gui-manual/teststand/customsteptypes/checkstop) step inside of your TestStand sequence file. See [stop conditions](/en/docs/ltt/documentation/ltt-gui-manual/teststand/processmodel/orderofexecution#stop-conditions) for more informations.

It may happen, that a test station refuses to stop. This can have several reasons:

* no proper usage of the [Check For Stop](/en/docs/ltt/documentation/ltt-gui-manual/teststand/customsteptypes/checkstop) step (infinite loop)
* a blocking call to an external code module (LabView, .NET)
* long time to reach the next [Check For Stop](/en/docs/ltt/documentation/ltt-gui-manual/teststand/customsteptypes/checkstop) step

In such cases you can **terminate** a test station (Shift+F9). A termination request will end the execution of the selected test station, no matter where the execution currently is and whether a [Check For Stop](/en/docs/ltt/documentation/ltt-gui-manual/teststand/customsteptypes/checkstop) step is used or not!

> Terminating test stations still perform all cleanup steps defined in the TestStand sequence file.

The termination will **not work** however if the test station execution has a (infinite?) **blocking call** to an external code module. If that is the case you can press Shift+F9 again. This will change the termination request to an abort request.

> Aborting test stations **do not** perform any cleanup steps defined in the TestStand sequence file. This may lead to leaving the system in a dangerous state, possibly causing harm to the device under test!