• TermDescription
  • Daughterboard

    A small PCB that when connected to an RTU converts from one communication protocol to another to allow the rtu to communicate with the host.

  • De-energize

    To remove power.

  • Direct Current (DC)

    Electrical current that travels only in one direction and has negative and positive polarity. It may or may not have an AC ripple component. DC sources that are unfiltered should be referred to as full-wave or half-wave rectified circuits.

  • DNS

    DNS is an abbreviation for Domain Name System, a system for naming computers and network services that is organized into a hierarchy of domains. DNS naming is used in TCP/IP networks, such as the Internet, to locate computers and services through user-friendly names. When a user enters a DNS name in an application, DNS services can resolve the name to other information associated with the name, such as an IP address.

  • DOLT

    Door Open Too Long: A door has been in the open state longer than the programmed maximum time allowed. This is one of the most common alarms in a system. A DPS (door position switch) is used to determine if the door is opened or closed.

  • Door Forced

    A door that has been entered without using the proper method of entry. This usually is determined by the change of the DPS state without a relay or valid card read at the door or portal being monitored for activity.

  • Double pole, double throw, (DPDT)

    A term used to describe a switch or relay output contact form (2form C) in which two separate switches operating simultaneously, each with a separate normal closed contract and a common connection. This form is used to make and break two separate circuits.

  • DPS

    Door Position Switch: A switch used to determine the position of a door. They usually are a magnetic reed switch which are triggered by a magnet installed in the top of a door. When the door lines up with the switch in the closed position the switch provides a dry contact signal back to the system.

  • Dry contract

    Metallic points making (closing) or breaking (opening) a circuit. The switch circuit must have its own source of power and is merely routed through the dry contacts.