The data acquisition component uses 16-bit analog-digital
conversion
and has better accuracty than typical 8- or 12-bit EMCS systems. The
higher resolution and accuracy add stability and long-term reliability.
The system is high-speed with the capability to trend all points at
1-second intervals. The data acquisition system (DAQ) has the following
components:
-
Host Server
-
LONWORKS adapter
-
Three LIO controllers
-
Six IO-12 devices
-
Interface Software
Host Server
The DAQ host is a TCP/IP-based network server. It incorporates a 66MHz
processor, 16MB of RAM, 840MB hard drive, multi-tasking Linux operating
system and compact size. The user can configure and operate the system
over the Internet or local network. An internal web server allows for
web-based
setup of controllers. The Site Manager Software has a Windows Graphical
User Interface
(GUI) that allows for local or remote review, backup, or adjustment of
the system. The server has two serial ports and can communicate over LONWORKS
and RS-485 to distributed controllers. The host controls and collects data
from the connected devices.
The unit is encased in a metal enclosure, shielding it
from EMF and
other forms of interference. Power is supplied from a dedicated 24-volt
AC transformer. It can supply 24-volt DC excitation for passive sensors
and receive 0-10 volt or 4-20mA input. The host itself can collect
sensor data from up to 12 inputs and control up to eight outputs; it can
also connect to fifteen distributed controllers which collect additional
sensor data.
Controllers
A controller's function is to collect data from connected equipment;
it can only relay signal back to the host server. The controllers handle
various inputs easily and can also supply excitation 24-volt DC power for
passive sensors. Power is supplied to each controller from a dedicated
24-volt AC transformer.
Three LIO controllers are distributed from a LONWORKS
adapter. A controller
can receive up to 12 inputs and control up to 8 outputs. Thirty-one of
36 available points are used at the demonstration site.
The IO-12 controller can receive 5 inputs and send 5
output signals.
It is small in size and easy to deploy. Sixteen of 30 available points
are in use. Three controllers are located in the basement and three in
the penthouse; they are connected to the host server using RS-485.
User Interface
There are two user interfaces for the data acquisition system: One
is a Windows-based graphical user interface (GUI) software and the other
is a web-based interface. The GUI connects to the server over a local or
remote connection and is used to view, backup, or configure the system.
The web interface allows stopping and starting of trends and has configuration
and upgrade capabilities. These are currently operated by project staff
and not by the building operator. The building operator has access to additional
data
visualization software.
