A distributed control system or DCS, in its current concept, is used to control a whole production site or multiple process plant on one geographical location. The distributed part means that the control decisions are made by controllers that are controlling a part of the process. The controllers used to control the different parts, should be able to take care of their own process and produce without needing a supervisory system. Obviously the supervisory system can add benefits and add higher operational efficiency, and so PCS 7 would be a good fit for these solutions.
When looking at a multi controller architecture, PCS 7 is one of the best platforms you can base your automation on. The single scada, multi controller setup of PCS 7, makes it easy for operators to do their work based on a logical (S88 based) design of the operator stations. This means that the operator stations do not need to reflect any multi controller architecture, instead the operator sees one contiguous operating system, and the abstraction to a multi controller platform is only visible in the engineering or maintenance systems.
The plant can be divided in a technical hierarchy based on an ISA S88 design or you can apply KKS or any other logical design structure. This design structure will allow you to subdivide the plant into program “folders” or functions that you can then divide across multiple logic controllers. These logic controller can be the Siemens 410CPU, but most other types of controllers can be used to load logic into. When using 410, 412,414,416 or 417 CPUs from Siemens, the logic for the control loops can be created in the PCS 7 logic editors like CFC or SFC.
Because the system in a DCS should be able to be loaded into manufacturer independent controllers, and still be able to connect to the main visualisation system, Siemens has developed OpenOS for PCS 7. This software system allows the DCS visualisation system to visualise data from all different controllers and/or OPC or modbus protocols. If you would like to exchange data between two controllers, these must still be interfaced separately. This can however be done using a wide variety of protocols that are industry standards.
Connecting multiple controllers can also be done in a server/client way, where you can have the AS410 CPU run a master program and a unit controller execute the actions given to it by the PCS 7 AS410 controller. This can be useful when running Batch recipes. But it could also be useful for integration of package unit controllers that run their visualisation independently, but need a start/stop command or permissions to be cleared by a main process controlling PLC.
For PCS 7 you can easily integrate PLCs by manufacturers like:
or even legacy Siemens PLCs can be connected to a new DCS visualisation system, which could allow you to migrate controllers and visualisation independently from a legacy Siemens DCS. Legacy Siemens controllers include:
Even new controllers like TIA Portal controllers (S7-1200 adn S7-1500) or the latest S7-1500H can be connected to a PCS 7 DCS.
PCS 7 can be linked to all of your existing site systems. For instance, a connection to OsiSoft PI or aspentech can be made, but many other historians can also be connected. If you don’t have a historian currently, it is advised to have one, and PCS 7 even has its own historian that can be integrated.
This can also be said for any process device management system. Because PCS 7 has modules that support heart technology, Profinet and profibus PA, a lot of transmitters can be accessed by a process device management toolkit. Using the PCS 7 PDM (process device manager) software allows for additional integration of all device information and data sheets into the visualisation system. This makes it easy to collect all data on one object in the control system, and this will give the operators a clear understanding of where information can be found.
The visualisation system can also be extended with a maintenance management system. This maintenance system can be loaded onto a separate maintenance computer, but also it can be used through the main operator visualisation system.
A number of auxiliary system can be connected with a PCS 7 controller. These systems can be for instance:
Most system can be linked to a PCS 7 PLC, so it can use the data in the program loops. Other systems can be linked directly to the visualisation, if they do not need to share any data with the PLC. This feature can be used for visualising states of a power management system or a remote sensor for instance.
Because the PCS 7 has a process safety system included in its standard offering, a SIS Compact CPU can be used to integrate an SIS into your DCS. This allows for programming of the SIS inside the PCS 7 toolset, and also allows for a combine visualisation. Another way of including safety control is to load a safety program into a PCS 7 410CPU. This will make the controller into an ICSS controller, and will save you the cost of buying an additional SIS Compact controller.
The library that comes with the PCS 7 Safety system has standard, TÜV certified, logic blocks in it that will allow you to configure the safety loops quickly with pre-apporved functions. Safety IO modules can also be inserted into the standard IO racks, and will then be configured to use Profinet as their communication protocol. This fill integration of programming tools, IO modules, ways of configuration and visualisation, will make sure that the service engineers will only need to learn one way a diagnosing a problem. They can then apply that knowledge all across the DCS system.
All these advantages make PCS 7 a system that can effectively be used as a DCS or ICSS. iAUTOMATION makes sure system like PCS 7, but also T3000, TIA Portal, ABB 800xA, Emerson DeltaV, Emerson Ovation, Rockwell FactoryTalk or any other solution will be configured right for your site. If you would like more information on DCS or ICSS systems, or if you have a difficult industrial automation issue that you would like to have solved? Come and speak with iAUTOMATION, send us an email at email@example.com or talk to us on linkedin, and let us help you.
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