Specifications - City of Montpelier, Vermont

Montpelier District HeatingCity of Montpelier, VTIssue Date:September 28, 2012Title:15900 – Direct Digital Control SystemPage #:21 of 401. Service Port. Each controller shall provide a service communication port forconnection to a Portable Operator's Terminal. Connection shall be extended tospace temperature sensor ports where shown on drawings.2. Signal Management. BC and ASC operating systems shall manage input andoutput communication signals to allow distributed controllers to share real andvirtual object information and to allow for central monitoring and alarms.3. Data Sharing. Each BC and AAC shall share data as required with eachnetworked BC and AAC.4. StandAlone Operation. Each piece of equipment specified in Section 23 09 93shall be controlled by a single controller to provide standalone control in theevent of communication failure. All I/O points specified for a piece ofequipment shall be integral to its controller. Provide stable and reliable standalone control using default values or other method for values normally read overthe network.D. Environment. Controller hardware shall be suitable for anticipated ambient conditions.1. Controllers used outdoors or in wet ambient conditions shall be mounted inwaterproof enclosures and shall be rated for operation at 29°C to 60°C (20°Fto 140°F).2. Controllers used in conditioned space shall be mounted in dustprotectiveenclosures and shall be rated for operation at 0°C to 50°C (32°F to 120°F).E. Keypad. Provide a local keypad and display for each BC and AAC. Operator shall beable to use keypad to view and edit data. Keypad and display shall require password toprevent unauthorized use. If the manufacturer does not normally provide a keypad anddisplay for each BC and AAC, provide the software and any interface cabling needed touse a laptop computer as a Portable Operator's Terminal for the system.F. RealTime Clock. Controllers that perform scheduling shall have a realtime clock.G. Serviceability.1. Controllers shall have diagnostic LEDs for power, communication, andprocessor.2. Wires shall be connected to a fieldremovable modular terminal strip or to atermination card connected by a ribbon cable.H. Each BC and AAC shall continually check its processor and memory circuit status andshall generate an alarm on abnormal operation. System shall continuously checkcontroller network and generate alarm for each controller that fails to respond.I. Memory.1. Controller memory shall support operating system, database, and programmingrequirements.2. Each BC and AAC shall retain BIOS and application programming for at least72 hours in the event of power loss.DIRECT DIGITAL CONTROL SYSTEMS1597221