Print this page.Getting Started

An Overview of Direct Digital Controls

Purpose of this Guide:

Due to the complexity and proprietary nature of DDC systems, it’s challenging to stay current with the designs, installations, operation and maintenance of DDC systems. DDC-Online.org was developed specifically to help building owners and consulting/specifying engineers with these issues. Getting Started is a tool to help professionals make more informed decisions and increase their knowledge about direct digital controls.

Chapter 1: Introduction to Direct Digital Control Systems

In this chapter:

This chapter covers the basics of an Energy Management System – a fully functional control system.

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Chapter 2: Control Response

In this chapter:

A review of five control responses and of the main benefits of DDC–improved effectiveness, improved operation efficiency and increased energy efficiency.

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Chapter 3: Elements of a Direct Digital Control System

In this chapter:

Included in this section: data classification - type, flow and source: and characteristics of the software supporting DDC systems.

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Input/Output Tutorial

Purpose of this Guide:

This portion of Getting Started provides descriptions of input and output devices written for someone new to the field or a seasoned engineer.

Chapter 1: Input/Output (I/O) Basics

In this chapter:

This section provides terms and definitions to help readers better understand material covered in next chapters.

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Chapter 2: Input Devices and Sensors

In this chapter:

In the world of HVAC control, there is basically one type of device used to complete a digital input (DI) circuit. A switch, employed in various forms, is this device. The following sections outline common switching devices currently used by the industry.

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Chapter 3: Output Devices

In this chapter:

There are numerous analog devices used in the HVAC controls world. Typically, analog output devices are used to provide modulating control of valves, dampers, electric motors through variable speed drives and a wide variety of other devices. The most common devices associated with analog outputs are sequencers, variable speed drives, silicon controlled rectifiers and actuators.

The section also reviews the most common devices associated with digital outputs–relays, contactors, starters and two-position actuators.

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