CEMP-E
TI 811-12
18 August 1998
LAN Connected to
Central/Island Station
Network
Interface
Smart
Remote Terminal Unit
Field
Communication Bus
Panel
I/O Interface
Universal
Universal
To Utility
Programmable
Programmable
Systems
Controller
Controller
I/O Interface
I/O Interface
To Utility
To Utility
Systems
Systems
Figure 4-5. Smart Field Panel and Universal Programmable Controllers (System with LAN-based Smart
Field Panels)
5. UNITARY CONTROLLERS. Unitary controllers serve as I/O devices and special purpose
controllers. Unitary controllers contain application software for the control of individual utility system
equipment, such as fan coil units, variable air volume terminal boxes and dual duct mixing boxes. Unlike
smart field panels, which are field programmable, unitary controllers have a fixed complement of I/O
functions and fixed (or minimally configurable) applications programs. Their program accommodates
specific operating requirements of utility system equipment by the selection of a small number of
setpoints and operating parameters. In addition, the unitary controller does not maintain a seven-day
calendar to accommodate varying daily schedules without communicating with the smart field panel.
Some UMCS manufacturers allow the unitary controllers to share a common communication circuit with
remote terminal units while others provide a separate communication circuit. Some manufacturers of
UMCS using LAN-based field equipment allow the unitary controllers to interface directly to the LAN
which connects smart field panels to the central/island station. Unitary controllers will be required to
communicate with smart field panels, and a separate data transmission circuit will be shown between the
smart field panel and connected unitary controllers. The relationships between smart field panels and
unitary controllers are shown in Figures 4-6 and 4-7.
4-5
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