Browse Definitions:
Definition

control loop

Contributor(s): Matthew Haughn

A control loop is a system made up of all the hardware components and software control functions needed for the measurement and adjustment of a variable that controls an individual process.

Control loops are the elemental building block of industrial control systems (ICS) such as supervisory control and data acquisition (SCADA) or distributed control systems (DCS). Each control loop commands a given variable in an industrial process.

Found everywhere ICS are used, control loops are part of the systems used in several processes, including:

  • Agriculture
  • Chemical plants
  • Pulp and Paper Mills
  • Quality control
  • Boiler controls and power plant
  • Nuclear power plants
  • Environmental control
  • Water treatment plants
  • Sewage treatment plants
  • Food and food processing
  • Metal and mines
  • Pharmaceutical manufacturing
  • Sugar refining plants

A control loop is made of a number of components. Though the specifics vary, a control loop is generally made of a sensor, a controller and a final control element.  The sensor takes a reading of the process variable or a related measurement. The controller receives the signal from the sensor and then forwards it to instrumentation, to remote terminal units (RTU) and to final control elements where the process variable is adjusted, to be kept as desired at a set point.

There are two main types of control loops: open loops that take human input and closed loops that are fully autonomous. Some loops can be switched between closed and open. When open, a switchable loop is manually controllable and when closed it is fully automated.

This was last updated in September 2017

Continue Reading About control loop

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

SearchSecurity

  • biometrics

    Biometrics is the measurement and statistical analysis of people's unique physical and behavioral characteristics.

  • principle of least privilege (POLP)

    The principle of least privilege (POLP), an important concept in computer security, is the practice of limiting access rights for...

  • identity management (ID management)

    Identity management (ID management) is the organizational process for identifying, authenticating and authorizing individuals or ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

SearchSolidStateStorage

  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.

Close