Operating Instructions

Glossary
46 Siemens Building Technologies, Inc.
heartbeat
Signal that one OPC Data Manager sends to another to indicate that it is functioning.
Hot Backup
Used for redundancy. Backup OPC Data Manager that operates normally except it does not write to the
OPC servers until the primary OPC Data Manager fails.
L
LAN
Local Area Network. Data communications network linking computers and nodes, usually within one
building or campus. It is typically an Ethernet or Token Ring protocol. An example of a LAN is the
Management Level Network used by Insight software.
M
MLN
Management Level Network. The communications connection between individual Insight workstations in
an APOGEE Automation System. It is highest network level in the building.
O
OPC
Object Linking and Embedding (OLE) for Process Control. Standard interface used in the process control
industry to connect field devices with process control or business applications.
P
PPCL
Powers Process Control Language. Programming language used to write APOGEE Automation System
control programs for building control and energy management functions. PPCL consists of various types
of statements, each performing a different task. These statements become ordered instructions called
control programs that are executed at the field panel. These control programs instruct the field panel on
how to perform calculations, evaluate control strategies, performed time based actions, and command
points.
R
RAS
Remote Access Service. A feature built into Windows NT and 2000 that allows a computer to dial in into
a network and access all the resources as if it were on the LAN.
redundancy
Feature that enables a system to use two OPC Data Managers: one to act as the primary OPC Data
Manager, and another to act as a backup if the primary fails.