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BUILDING MANAGEMENT SYSTEM FUNDAMENTALS
— Transmitting requests for display data.
— Transmitting requests for report data.
— Uploading and downloading of controller software.
— Transmitting digital and analog commands.
— Reading/writing controller database points including
limits, setpoints, times, and parameters.
— Coordinating global LAN server database including
graphic configurations, operator assignments and
segregation, history files, and schedule files.
— Entering or editing system-level processor programs.
— Configuring or editing zone-level processor programs.
Server
When using multiple operation/management-level
processors, one is defined as the database server, where all
current database resides. Any processor may initiate a system
change (graphic or text modification, operator assignment,
schedule, etc.), but all changes are made to the server database.
The server is a software function and may be a dedicated PC
or any other LAN processor.
All LAN processors operate from the server, which
periodically updates the databases of the other LAN
processors. When the server (LAN) is down, the processors
operate from their own database.
Security
System security software prevents unauthorized system
access and can limit authorized personnel to geographic areas
as well as function (acknowledge alarms, issue commands,
modify database, etc.). Top level operators assign security
passwords and enter security parameters for other operators.
If no keyboard or mouse activity occurs for a predetermined
time period, the operator is automatically signed-off. All
operator sign-on and sign-off activity is archived.
Alarm Processing
Upon receiving an alarm from a controller, operations-level
processors initiate alarm processing as follows:
— Determine if the alarm point is assigned to the receiving
processor.
— Rebroadcast the alarm to the server for archival and to
other LAN processors.
— If Assigned:
• Present an immediate alarm message display.
– Output alarm message to alarm printer.
– Alarm point text descriptor.
– Time/Date.
– Text action message.
– Present acknowledge button.
– Initiate audible.
• No audible.
• For timed duration or continuously.
• Fast, medium or slow beep rate.
• (Option) Automation Graphic Display.
• Present button for operator graphic display request.
— Present alarm status on graphics (point red if in alarm,
blinking if unacknowledged).
The alarm archive may be queried at any time to analyze
historical alarm activity.
Reports
BMS Software includes many system reports for display and
printout in addition to alarm reports.
Database reports document system software such as point
processing parameters, system text, controller configuration, etc.
The trend report utility allows for archival of data point
status and values for subsequent review. Archival may be based
upon a time interval or a change in status or value. Trend data
may be reviewed as archived or may be sorted and reduced,
such as "Print the maximum daily temperature from 3-16-96 to
5-16-96". Trend data may be presented in columnar format or
as a curve plot with up to eight points per display/printout.
Trend sample requirements are usually set-up in the controller
and automatically reported to the BMS thereafter.
Other standard reports may be:
• All point summary.
• Alarm summary.
• Disabled Points Log.
• Single System Summary (single AHU or single chiller).
• Controller Status Summary.
System Text
BMS system text includes unique names for all controllers,
PCs, peripherals, and active communications devices. Each
building, HVAC system, and hardware and software point also
has a unique name. Each alarm point includes an alarm message
(such as "call maintenance") and may have an extended unique
alarm instruction of up to 480 characters. Extended messages
typically tell a BMS operator what to do, what not to do, what
to investigate, who to call, which forms to fill out, what to order,
etc. Unique system text may be in any language which uses
ASCII Characters.
System Graphics
A standard graphics package is used to develop system
graphics. System graphics start at the total system level
including all buildings and systems and are structured in a
logical penetration scheme down to the point level. BMS
software allows total operator editing including adding new
graphics. System points may be used on multiple graphics.
Color is used to differentiate shapes and to define point
status. Red may be reserved for alarm, green may be reserved
for "Normal On", and yellow may be reserved for "Normal
ENGINEERING MANUAL OF AUTOMATIC CONTROL
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