Friday, September 9, 2011


AX-S4-MMS is an interface of EC 61850 for applications of windows supporting interface of OPC DA (data access) and DDE (Dynamic Data Exchange). It is characteristic implementations of functionality server/client. The standard is to utilize a platform of PC operating Windows 2000/XP for the server of IEC 61850 and access parameters process as items of OPC from OPC server arbitrary. The functionality of server is executed from the MMS-Ease Lite, it support reporting and write/read. The nodes of logical and objects data in the server are organized via a file of SCL that is brought into the server. There are alternatives to set items of mapped with read/write or read only authorization. The rate of scan i.e. how frequently the server of IEC 61850 should revise the amounts from the server of OPC, is every individual and grouped value are connected with a group. The user makes groups to which scan rates and permissions are related. This method the mainly important rates can be revised as frequent as one would like, at the same time as the less regularly utilized values can be revised less often. Through read demands the server reacts with the latest value or at the first set value obtained by the client of OPC. When write request the server writes the rate to the server of OPC before it transmits acknowledgment to the client of IEC 61850. The software also comprises a server of OPC and a client of IEC 61850 that can be arranged for accessing devices of IEC 61850 from applications of Windows.

It is proprietary solution of Siemens for communication between PC stations and PLC systems. The communication uses function protocol of Siemens proprietary S7, which is a technique to contact individual bytes or bits in the PLC memory area. The Softnet for Profibus comprises a server of OPC and a tools configuration OPC Scout. The server of OPC is incorporated in the project of Simatic and can access devices of S7 with the communication protocol of proprietary S7. From the Scout one of OPC can attach to the server of OPC and contact the variables in the process area and memory of the PLC. Groups can be made in the server of OPC in which intervals of transmission and items of member can be organized. Each position in the PLC memory area can be connected to an Item of OPC. The data OPC linking doesn’t provide any data conversation type, so an item of OPC floating-point type has to be connected to a type of floating-point in the PLC. The majority types of OLE data can be interpret using the interface of OPC from the PLC. The OPC data type notation interests are DINT and INT for integers bit length of 16 and 32 bits, X for Boolean, and REAL for 32 bits floating-point number.


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