contact inputs, timing and order of event sequences. If a fault condition is detected, output contacts operate to trip the associated circuit breaker(s). Parameter setting The logic is user-configurable and can vary from simply changing front panel switches or moving of circuit board jumpers to accessing the relay's internal parameter setting webpage via communications link on another computer hundreds of kilometers away. The relay may have an extensive collection of settings, beyond what can be entered via front panel knobs and dials, and these settings are transferred to the relay via an interface with a PC (personal computer), and this same PC interface may be used to collect event reports from the relay. Event recording In some relays, a short history of the entire sampled data is kept for oscillographic records. The event recording would include some means for the user to see the timing of key logic decisions, relay I/O (input/output) changes, and see, in an oscillographic fashion, at least the fundamental component of the incoming analogue parameters. Data display Digital/numerical relays provide a front panel display, or display on a terminal through a communication interface. This is used to display relay settings and real-time current/voltage values, etc. More complex digital relays will have metering and communication protocol ports, allowing the relay to become an element in a SCADA system. Communication ports may include RS-232/RS-485 or Ethernet (copper or fibre-optic). Communication languages may include Modbus, DNP3 or IEC61850 protocols. Comparison with other types By contrast, an electromechanical protective relay converts the voltages and currents to magnetic and electric forces and torques that press against spring tensions in the relay. The tension of the spring and taps on the electromagnetic coils in the relay are the main processes by which a user sets such a relay. In a solid-state relay, the incoming voltage and current wave-forms are monitored by analog circuits, not recorded or digitized. The analog values are compared to settings made by the user via potentiometers in the relay, and in some case, taps on transformers. In some solid-state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple. For instance, in some time overcurrent solid state relays, the incoming AC current is first converted into a small signal AC value, then the AC is fed into a rectifier and filter that converts the AC to a DC value proportionate to