This section describes tasks for the Universal Modbus controller Also known as remote terminal unit, RTU. A generic term for a device that is used to control and monitor one or more processes in field equipment. The most common control and monitoring device in an access control and security system is an access control panel. Other devices include security monitoring panels, elevator controllers, and fire monitoring devices. Controllers include programmable logic controllers (PLCs), loop controllers, bar code readers, and scientific analyzers. See also: C200 controller, control processor, CPM, hybrid controller, network node controller, PLC. that you perform either on the server The computer on which the Experion database software and server utilities run. See also: Experion server TPS. or from any Station Experion's main operator interface. Station presents information using a series of displays. See also: display..