SCADA: A Definition And Overview

SCADA Definition: Supervisory Control And Data Acquisition The Basics of SCADA SCADA programs are used in industrial process control applications for centralised monitoring and recording of pumps, tank levels, switches, temperatures etc. SCADA systems are also referred to as HMI (Human Machine Interfaces), or the less politically correct MMI (Man Machine Interfaces). A SCADA program normally runs on a PC and communicates with external instrumentation and control devices. Communications methods can be via direct serial link, radio, modem, fieldbus or Ethernet links. If a mixture of instruments with differing communication interfaces and protocols need to be connected, then converters can be used. SCADA is often used on remote data acquisition systems where the data is viewed and recorded centrally. The SCADA program has a user configured database which tells the software about the connected instrumentation and which parameters within the instruments are to be accessed. The database may also hold information on how often the parameters of the instruments are accessed and if a parameter is a read only value (e.g. a measured value) or read / write, allowing the operator to change a value (e.g. an alarm setpoint). The parameters of the instrument being accessed are normally split between analogue (numeric) or logic (digital). When running, the SCADA software continuously updates its own database with the latest analogue and digital values collected from the instrumentation.