Trane TRG-TRC014-EN manual Direct Digital Control DDC, Components of a VAV System, period two

period two

Components of a VAV System

notes

Direct Digital Control (DDC)

central air handler

	DDC/VAV
communicating	terminal units
building automation
system (BAS)	Figure 46

A digitally-controlledterminal unit has an airflow-modulation device operated with an electric actuator in the same manner as the electronic control option. The key difference between electronic control and direct digital control is that the digital controller uses a microprocessor as the intelligence behind the control of the terminal unit. This microprocessor enables digital communication between the unit controller and the central building automation system.

The result is a system that can be monitored from a central point, offers control flexibility, and enables system-optimized control strategies. Buildings can be controlled more intelligently because the data (such as airflow, damper position, fan, and heat status) is available to perform complex system-control strategies and diagnostics from a central monitoring station.

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