## PV Connectivity

### Connect to PV

You have to configure your CSS to connect to your EPICS system before BOY can connect to a real EPICS PV. This is configured in the preference page `CSS->Preferences->CSS Core->EPICS`. For more details, please see here

You can also use local or simulated PV which are created in CSS. See here

In BOY, just specify the PV Name property of a PV widget will make the widget connect to the PV automatically in run mode.

### Disconnected Status

There is a common look for all the disconnected PV widgets. It will show this disconnection border if any one of the PVs on the widget is disconnected. The information about the disconnected PVs will show in the tooltip.

### Null value border

If any one of the PVs on the widget has null value, it will show a dotted invalid border as below. The information about the null value PVs will show in the tooltip. If the null value PV is the main PV of the widget, the value displayed in the widget is meaningless.

### PV Security

If the main PV (specified by `PV Name` property) of the widget is not allowed to write, the control widgets will be disabled.