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Entry type: FAQ Entry ID: 63112181, Entry date: 04/25/2014

Implement the communication connection of the MSS 3RK3 to the different S7 controllers via AS-Interface

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How do I implement the communication connection of the MSS 3RK3 to the different S7 controllers via AS-Interface?




There are AS-i slave profiles for serial data transmission. The MSS 3RK3 Advanced uses these slave profiles to transmit diagnostic data to the higher-level controller. It is also possible to transmit control commands from the PLC to the MSS. Transmission via AS-Interface for the MSS 3RK3 Advanced and ASIsafe central modules uses the CTT2 protocol. A CTT2 slave is simulated by the central module for this purpose. Depending on the number of slaves on the bus, serial transmission of the data takes up to a maximum of 1.31 s.
There are two options for data transmission by means of the CTT2 protocol, cyclic data transmission and acyclic data transmission. Device messages (e.g., group errors) result in an entry in the cyclic data, the message data. All elements with their pending messages are entered in acyclic data. They can be read out with a command.
The following FAQ describes the cyclic CTT2 data exchange between MSS 3RK3 Advanced/ASIsafe and the different controllers of the SIMATIC family and explains the configuration of the AS-i masters as well as the programming in the Step 7 and TIA Portal (V12) engineering system. It also includes an explanation for another option of connecting the MSS 3RK3 by means of standard I/O slaves. This offers the advantage of faster data exchange, for example, for time-sensitive applications.

FAQ_63112181_Diagnostic_options_of_the_MSS_with_AS-i_functionality_EN.pdf (1973 KB) ( 1973 KB )  


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AS-Interface, SIMATIC S7-300/S7-400, SIRIUS



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