SACA SCADA Systems

Question 1

In a SCADA system, what is the primary role of a Remote Terminal Unit (RTU)?

Accepted Answer

To collect field data from sensors and transmit it to the master station

Answer

An RTU is a ruggedized field device that interfaces directly with sensors and actuators, collects real-time data (e.g., pressure, temperature, valve position), and transmits it over a communication network to the SCADA master station (MTU) for display and logging.

Question 2

Which communication protocol is most commonly associated with legacy SCADA systems communicating with RTUs over serial links?

Accepted Answer

DNP3 (Distributed Network Protocol 3)

Answer

DNP3 was designed specifically for SCADA communication between master stations and RTUs, particularly in electric utilities and water/wastewater sectors. It supports time-stamping, data integrity features, and efficient polling over low-bandwidth serial links — features absent from general IT protocols.

Question 3

What distinguishes a SCADA system from a Distributed Control System (DCS)?

Accepted Answer

SCADA is designed for geographically dispersed monitoring over wide areas; DCS is optimized for tightly integrated continuous process control at a single facility

Answer

SCADA excels at supervisory monitoring and control over large geographic areas (pipelines, power grids, water distribution) with relatively slow scan rates. DCS is optimized for tightly coupled continuous process control (refineries, chemical plants) at one facility with fast, deterministic control loops.

Question 4

A SCADA historian serves which primary function in an industrial operation?

Accepted Answer

It stores time-series process data for trend analysis, reporting, and regulatory compliance

Answer

A SCADA historian (e.g., OSIsoft PI, Wonderware Historian) is a specialized time-series database that archives process values at high frequency over long periods. This data supports trend analysis, production reporting, equipment diagnostics, and regulatory recordkeeping.

Question 5

In SCADA terminology, what is an HMI's primary function?

Accepted Answer

To provide operators with a graphical interface for monitoring process status and issuing control commands

Answer

The Human-Machine Interface (HMI) is the graphical front-end of the SCADA system. It displays real-time process mimics, trend charts, and alarms, and allows operators to issue commands (e.g., open a valve, start a pump) to the underlying control hardware.

SACA - Smart Automation Certification Alliance Practice Test

SACA - Smart Automation Certification Alliance Practice Test

SACA SCADA Systems