Hot Plug

PCI Express supports native hot-plug though hot-plug support in a device is not mandatory. Some of the elements found in a PCI Express hot plug system are:

• Indicators which show the power and attention state of the slot.

• Manually-operated Retention Latch (MRL) that holds add-in cards in place.

• MRL Sensor that allow the port and system software to detect the MRL being opened.

• Electromechanical Interlock which prevents removal of add-in cards while slot is powered.

• Attention Button that allows user to request hot-plug operations.

• Software User Interface that allows user to request hot-plug operations.

• Slot Numbering for visual identification of slots.

When a port has no connection or a removal event occurs, the port transmitter moves to the electrical high impedance detect state. The receiver remains in the electrical low impedance state.