COMMUNICATIONS
4 CONTROL
Communication networks within the process control/automation
industry are used to transmit instructions and pass data between
field instrumentation and a
SCADA or a
DCS and possibly to a
LAN
or
WAN for corporate use. To achieve this
then the system is required to communicate information across
three distinctive networks.
Firstly the Field Network, Instructions and data are passed
from/to instrumentation in the field to a controller. This
controller may be a
PLC,
RTU
or a
DCS.
Controllers may be stand alone where no information is passed
from this to other networks or it may be a subsystem within
a larger network that communicates to other controllers and/or
computers. This is the second layer and is known as the Control
Network.
PI is the third layer
in a process control system. Information about the process
is communicated across this network usually for archiving
and reporting across a
LAN or
WAN.
The three networks mentioned use a variety of specific technologies
to communicate this information and must meet certain requirements
such as robustness and compatibility to ensure an acceptable
solution. With the aid of modern low cost technology enabling
network connectivity even in the smallest of plants, understanding
the connectivity from the field to control system and business
network has become an integral part of an engineer’s role,
whether they are involved in design, installation and commissioning
or maintaining a plant. This website is being developed to
present useful and relevant information concerning the standard
communication methods used within industry.
