Data Acquisition

Figure 8.9SCPI instrument modelThe functional components of the SCPI instrument model are described in the followingsections:The measurement function component is used to convert a signal into a preprocessedform. It is divided into three distinct parts:INPutPerforms signal conditioning, such as filtering, biasingand attenuation on the raw incoming signal.SENseConverts the conditioned input signal into a data formatthat can be manipulated by the user. This functioncontrols parameters such as range, resolution, gate time,and normal mode rejection.CALCulateConverts the data into a format that is more useful for aparticular application, such as converting the data toengineering units.The measurement function described by the three functions above is specified by thesignal parameters, and not by the instrument’s functionality. This usually provides thehighest level of compatibility by allowing different instruments that make the samemeasurements to be interchanged without changing the SCPI command.The signal generation function converts internal data to real-world signals. It is alsodivided into three distinct parts:OUTputThis signal block conditions the output signal byfiltering, attenuation and biasing.SOURce Generates a signal based on specific characteristics andinternal data, specifying such signal parameters ascurrent, voltage, power and frequency.CALCulate This functional block converts the data from one set ofengineering units to another and also takes into accountabnormalities, which occur in the generation of thesignal data.The signal routing function controls the connection of a signal to the internal functions ofa particular instrument. The TRIGger component synchronizes instrument options withexternal conditions, such as an analog or digital signal, internal instrument events