Distributed Control System Architecture

Here is an example of the highly flexible UCOS distributed control system architecture. Click any component in the architecture to learn more about it.

SystemsPLC + HMI SCADAArchitectureSequencingDistributed Control System - DCSArchitecture Regulatory ControlMaster Station SCADAMaster/Remote ControlArchitectureCommunications

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Details

Engineering & Operator Workstations

The Engineering Workstation (EWS) is for project development, including configuration of graphics, logic, alarms, security, etc. Typically, the EWS is a PC running Windows 2000/XP.

The Operator Workstation (OWS) provides the operator interface, including color graphics, faceplates, alarms, logging, trends, diagnostics, etc. The EWS includes an OWS for testing and troubleshooting. Typically, the OWS is a PC running Windows 2000/XP.

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Process Historical Archivers

The Process Historical Archiver (PHA) stores and retrieves historical data collected by the FCU, microFCU, SDS, or any other intelligent device in the system. The PHA can run standalone or can share an OWS workstation. Typically, the PHA is a PC running Windows 2000/XP.

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Controllers The Field Control Unit (FCU) executes sequential and regulatory logic and

directly scans I/O. Depending on the FCU's configuration, you can scan multiple brands of I/O from one unit. The FCU runs QNX, a real-time operating system, and is typically a PLC or a ruggedized industrial computer available in a variety of form factors.

The I/O Subsystem supports I/O from all the standard industry suppliers. In a UCOS configuration, you don't necessarily need PLCs – just PLC I/O.

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The SCADA Data Server (SDS) interfaces UCOS to PLCs, Fieldbus technologies, RTUs, PLC I/O, and other third-party devices.

The SDS can execute sequential and regulatory logic and directly scan supported I/O. It can also act as a data gateway allowing UCOS to work with just about any device you can think of.

Typically, an SDS is a ruggedized industrial computer running Windows 2000/XP, although direct I/O scanning is run under QNX, the leading real-time operating system.

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The UCOS microFCU is a small, low-powered PLC that executes sequential and regulatory logic and directly scans onboard I/O. It can replace RTUs at a

significant reduction in cost and power consumption – plus it can provide local intelligent control of devices, which RTUs can't do.

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Networking and Communications

UCOS supports redundant and non-redundant fiber optic and Ethernet local networks using the TCP/IP networking protocol for standardized, advanced application connectivity.

The LAN/WAN can be extended to other sites inside or outside the plant using such remote communications technologies as satellite, radio, microwave, and dial-up running such standard protocols as TCP/IP, Modbus, OPC, DDE, etc.

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Facility or Process 1

This area illustrates a process that requires significant monitoring and control. A local operator uses the color graphic Operator Workstation (OWS) to monitor and control the process, and the Field Control Unit (FCU) executes sequential and regulatory control logic.

Exception-based technology is used to transfer only data that needs to be archived or shared with other nodes, thus minimizing communications traffic.

Local monitoring and control also helps insulate this site from failures elsewhere in the system. An optional redundant configuration makes even local shutdowns rare.

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Facility or Process 2

Here UCOS serves as a true data concentrator. The process at this site does not require a local operator, but does benefit from local control.

The SCADA Data Server (SDS) interfaces UCOS to PLCs, Fieldbus technologies, RTUs, PLC I/O, and other third-party devices.

The SDS can execute sequential and regulatory logic and directly scan supported I/O. It can also act as a data gateway allowing UCOS to work with just about any device you can think of.

Just like facility or process 1, the configuration at this location minimizes communication traffic, isolates the location from failures elsewhere, and is available in a

redundant configuration.

Typically, an SDS is a ruggedized industrial computer running Windows 2000/XP, although direct I/O scanning is run under QNX, the leading real-time operating system.

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Facility or Process 3

This area requires local control but does not necessarily need an on site operator.

The UCOS microFCU is a small PLC that executes sequential and regulatory logic and directly scans onboard I/O.

The UCOS microFCU can replace RTUs at a significant reduction in cost and power consumption – plus it can provide local intelligent control of devices, which RTUs can't do.

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Now let's take a look at regulatory control concepts in UCOS.

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