Remote Telemetry Unit (RTU): Glossary Of Related Terms
An alarm master is the core of a monitoring system. An alarm master collects alarms from remote telemetry units (RTUs) and displays them for one or more operators.
Primarily found on an advanced remote telemetry unit. An input that accepts a continuous range of states from an analog sensor of some kind, such as temperature or humidity.
A control relay is a switch on a remote telemetry unit that another device may be wired into to achieve remote control of that device. Typically used to activate generators or unlock doors, without having to travel to the site.
Derived controls apply rule sets to incoming alarms to control complex automatic responses to emergencies. There are two types of derived control: echo and formula.
Discrete alarm inputs
Found on a remote telemetry unit. An alarm input that can be one of only 2 states: Alarm or Clear.
A legacy device is an older RTU or device that you may still use it in your current network. Unfortunately it might not be manufactured any longer, that might be out dated, or that the manufacturer no longer supports/ provides replacement parts.
A ping alarm is an automatic alert sent to you when one of your LAN connected devices fails to respond to successive pings. Modern alarm monitoring equipment, such as a remote telemetry unit, can be configured to send scheduled pings to a large number of devices every few minutes (some remote telemetry units support ping alarming to as many as 32 distinct IP addresses simultaneously.
Programmable Logic Controller (PLC)
A programmable logic controller is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. PLCs are typically considered the equivalent of a remote telemetry unit in production Supervisory Control and Data Acquisition (SCADA) environments. They do, however, suffer from much lower point capacities and reporting capabilites.
An Simple Network Management Protocol (SNMP) agent that translates non-SNMP messages and inputs to SNMP. In network alarm monitoring, a proxy agent is usually a remote telemetry unit that converts contact closure inputs to SNMP traps, like the NetGuardian 832A.
Small programs that are put into a remote telemetry unit to perform simple tasks.
SNMP agents expose management data on the managed systems as variables (such as "free memory", "system name", "number of running processes", "default route"). The managing system can retrieve the information through the GET, GETNEXT and GETBULK protocol operations or the agent will send data without being asked using TRAP or INFORM protocol operations.