This diagram illustrates a complete RTD interfacing circuit using the ADuC7060/1 which replaces the components in the circuit discussed in the previous slides. Note the added R/C filtering and also that there are now four wires connected to the RTD. This four-wire connection is the best way to minimize errors caused by lead resistance which can otherwise be significant. Off-the-shelf RTDs are typically available in 2-wire, 3-wire, or 4-wire configurations. The interface circuit is no different for 2 and 3 wire RTDs except that the excitation and sense signals must share a single wire, and so errors will be worse, especially with significant lead length. As with the bridge transducer implementation previously looked at, just add a power supply and some sort of serial connection to the outside world (and possibly over-voltage protection diodes on the four terminal block nodes) then this diagram represents a complete system. Once again the benefits of integration can be seen here.