# PS Module

All power supply (PS) modules have the following mandatory standard parameters:

| Parameter      | Meaning                                                                                                                                                                                                                                                                                                                           | Examples                                                       |
| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------- |
| Resource       | The connection information needed to connect to this device. Depending on the type of device this can be a COM port, a GPIB address, an IP address or something else. Most drivers are based on VISA, which brings its own syntax to provide a GPIB or IP address. The VISA resource names can usually be looked up in NI Max.    | <p>COM1<br>GPIB0::1::INSTR<br>TCPIP::192.168.222.50::INSTR</p> |
| NominalVoltage | The initial voltage which should be set during device initialization.                                                                                                                                                                                                                                                             | 12.0                                                           |
| MinVoltage     | The lower voltage limit in V. This value can be changed through the [LTT GUI](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/lttgui/dialogs/f10testparameterconfiguration). The GUI will stop all running tests if this limit will be violated.                                                                        | 0                                                              |
| MaxVoltage     | The upper voltage limit in V. This value can be changed through the [LTT GUI](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/lttgui/dialogs/f10testparameterconfiguration). The GUI will stop all running tests if this limit will be violated.                                                                        | 19.0                                                           |
| CurrentLimit   | The max. current the power supply will regulate to in current mode (CC). This value can be changed through the [LTT GUI](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/lttgui/dialogs/f10testparameterconfiguration). If the actual load is greater than this current the voltage will drop, leading to malfunctions. | 100                                                            |

Depending on the specific PS module, there might be additional parameters, which are described [here](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/configuration/moduleconfiguration/ps/ps-parameters).

Per default a power supply configured here is controlled by the underlying LTT software layer. This means the PS is **automatically initialized and configured to the provided parameters**. Nevertheless, in your [testplan](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/teststand) you can still change voltage and/or current during runtime, as well as access the latest values read from that PS (see [here](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/teststand/hardware-control)). But you have **no control** over when the PS is initialized/closed and when the output is turned on/off.

## TestStand-only control

There are situations in which you might need **more control over your power supply** from within TestStand. For such situations you can provide the `tsonly="true"` attribute to the `Module` node.

```xml
<Module name="PS1" tsonly="true">
...
</Module>
```

If you do so, **you are in charge** of initializing, setting and closing the power supply properly. [Read here to learn how to do](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/teststand/hardware-control).

{% hint style="info" %}
You can access the PS control panel through [GUI](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/lttgui/hwcontrol/ps-control-gui) and also via [TestStand](https://docs.irs.systems/ltt/documentation/ltt-gui-manual/teststand/hardware-control). However, the control panel is not available for self-controlled (`tsonly="true"`) power supplies.
{% endhint %}