Chemical Engineering March 2019 - 48

The operator uses the operation and monitoring
environment specific to each external controller.
The UGS provides operation and monitoring on the
same screens for all controllers.
Operator
HIS
HMI
HIS
Vnet/IP
SCADA
FCS
FCS
Open network
External controller
(FCN/FCJ, OPC, PLC, etc.)
Yokogawa
FIGURE 3. On the left diagram, different operator interfaces are used to monitor different systems. On the
right, a unified gateway station (UGS) provides monitoring on the same screens for all the controllers in a
plant or facility (HMI = human-machine interface; HIS = human interface station; FCS = field control station)
needed to any controller, it can also
be supported, either directly, or by a
third-party library from an OPC vendor.
The UGS continually monitors
the status of communications with
external controllers, alerting operators
to any issues.
The UGS controls and monitors
subsystem communication data by
treating it the same as the DCS faceplate
blocks. It also allows graphics and
Yokogawa
HIS
trends to be handled as native DCS
tags on the operator station (Figure 4).
Unified alarm monitoring
The UGS translates the function
blocks in each controller into native
DCS function blocks, and vice versa.
In a DCS, function blocks are often
used for alarm monitoring, in the
same way as for data operation and
monitoring. Monitoring external conENG
Operating
at scale
To handle the large data volumes in
an entire plant or facility, the UGS
should be capable of accommodating
a large number of tags, typically
up to 100,000 with 450,000 data
items, and should be able to connect
to hundreds of external controllers.
At that size, a UGS can acquire
6,400 data items per second
from external controllers and send
640 data items per second to them,
and the operator stations can read
6,400 data items per second from
and write 640 data items per second
to the UGS itself.
Vnet/IP
FCS
UGS2
Ethernet
OPC server
Subsystem communication network
Subsystem communication network
Subsystem controllers
A unified set of engineering functions
should be part of the UGS,
including import functions. With this
capability, engineering information
defined for the UGS can be maintained
as part of a project, the same
as for all the other DCS engineering
information. A smart import function
of the DCS, an OPC Browse
command, a CSV import command
for general data files in the comma
separated values format, and other
options should be available to import
data. After importing data, tags
should be automatically generated.
The next step should be the downloading
of configuration information
to the operator station and the UGS.
This two-step process allows the
operator station to access the external
controllers.
Subsystem controllers
FIGURE 4. The unified gateway station (UGS) in this system architecture diagram acts as a gateway between
the DCS and the subsystem controllers
48
Especially important for oil-andgas
applications is the capability to
apply online partial changes. This is
also true for sequential operations
in process plants. The UGS should
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
MARCH 2019
Open network
External controller
(FCN/FCJ, OPC, PLC, etc.)
UGS
Introducing UGS
Vnet/IP
CAMS for HIS
message monitor
Operator
Operation and monitoring window
trollers is done by monitoring alarms
generated in the function blocks.
The function blocks of the UGS
convert alarms generated in external
controllers, and can also detect and
generate alarms. The data item faceplate,
and the annunciator faceplate,
enable alarm monitoring of external
controllers that do not have alarm
functions. For all alarms, the same
standard settings are used, providing
consistency among systems. Having
a unified alarm-monitoring system for
all controllers and all function blocks
produces a significant increase in
process safety.
http://WWW.CHEMENGONLINE.COM
Chemical Engineering March 2019

Table of Contents for the Digital Edition of Chemical Engineering March 2019
