diff --git a/satrs-core/src/device.rs b/satrs-core/src/device.rs
new file mode 100644
index 0000000..e69de29
diff --git a/satrs-core/src/power.rs b/satrs-core/src/power.rs
index cc00e2b..0901acd 100644
--- a/satrs-core/src/power.rs
+++ b/satrs-core/src/power.rs
@@ -1,7 +1,12 @@
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
 
+/// Generic trait for a device capable of switching itself on or off.
 pub trait PowerSwitch {
-    fn switch_on(&mut self);
-    fn switch_off(&mut self);
+    type Error;
+
+    fn switch_on(&mut self) -> Result<(), Self::Error>;
+    fn switch_off(&mut self) -> Result<(), Self::Error>;
 
     fn is_switch_on(&self) -> bool {
         self.switch_state() == SwitchState::On
@@ -10,19 +15,41 @@ pub trait PowerSwitch {
     fn switch_state(&self) -> SwitchState;
 }
 
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum SwitchState {
     Off = 0,
     On = 1,
-    Unknown = 2
+    Unknown = 2,
+    Faulty = 3
 }
 
+pub type SwitchId = u16;
+
+/// Generic trait for a device capable of turning on and off switches.
 pub trait PowerSwitcher {
-    fn send_switch_on_cmd(&mut self, switch_nr: u16);
-    fn send_switch_off_cmd(&mut self, switch_nr: u16);
+    type Error;
 
-    fn get_switch_state(&mut self, switch_nr: u16) -> SwitchState;
+    fn send_switch_on_cmd(&mut self, switch_id: SwitchId) -> Result<(), Self::Error>;
+    fn send_switch_off_cmd(&mut self, switch_id: SwitchId) -> Result<(), Self::Error>;
 
-    fn get_is_switch_on(&mut self) -> bool {
-        self.get_switch_state() == SwitchState::On
+    fn switch_on<T: PowerSwitch>(&mut self, switch: &mut T) -> Result<(), <T as PowerSwitch>::Error> {
+        switch.switch_on()
     }
+    fn switch_off<T: PowerSwitch>(&mut self, switch: &mut T) -> Result<(), <T as PowerSwitch>::Error> {
+        switch.switch_off()
+    }
+
+    /// Retrieve the switch state
+    fn get_switch_state(&mut self, switch_id: SwitchId) -> SwitchState;
+
+    fn get_is_switch_on(&mut self, switch_id: SwitchId) -> bool {
+        self.get_switch_state(switch_id) == SwitchState::On
+    }
+
+    /// The maximum delay it will take to change a switch.
+    ///
+    /// This may take into account the time to send a command, wait for it to be executed, and
+    /// see the switch changed.
+    fn switch_delay_ms(&self) -> u32;
 }
\ No newline at end of file