TCUs.
b.
TCUs shall automatically start-up on return of power after a
failure, and previous operating parameters shall exist or shall be
automatically downloaded from a digital controller on a higher
level LAN.
c.
TCUs do not require an internal clock if they get time information
from a higher level digital controller.
2.1.3
DDC Software
2.1.3.1
Sequence of Control
**************************************************************************
NOTE: The sequence of control shall be written to
include all conventional control operations (e.g.
temperature and pressure control loops), time event
operations, energy management functions (night
setback, reset schedules, and optimum start
routines), push button overrides, demand limiting,
safeties, and emergency conditions. The preferred
location for specifying and documenting the sequence
of control is directly on the project drawings.
**************************************************************************
Provide, in the digital controllers, software to execute the sequence of
control. Provide one registered copy of all software used to program
control sequences in all direct digital controllers and LAN controllers on
the computer workstation. Provide any access keys which restrict
programming language software functions or the ability to compile or
prepare programming for download to controllers. Provide final copy of
each program used in the system in both compiled and editable formats.
Where specially programmed factory configured smart controllers are used in
the system, provide minimum factory programming tools and specialized
controller programs ready for download to replacement controllers. At
minimum, controllers must be capable of performing programming functions
outlined in the following "Parameter Modification" section.
2.1.3.2
Parameter Modification
Provide software to modify control parameters. Parameter modification for
all controllers (high level and low level application specific) is through
the main workstation computer [and with laptop computer or keypad terminal
directly at each controller]. Modifications accomplished without having to
make changes directly in line-by-line programming. When the control program
is of the line-by-line type, database parameters in the following list that
take real number values require assignment of variable names so parameters
can be changed without modifying programming. Alternatively, block
programming languages shall provide for modification of these database
parameters in fill-in-the-blank screens. Parameters of like type, including
those in different high level and low level controllers, may be grouped
together for a single, global change. For example, an operator may group
all second floor space temperature setpoints into a group and raise the
setpoint by two degrees with a single command. The following parameters
shall be modifiable in this way:
a.
Setpoints
SECTION 15910N
Page 28
Previous Page
