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Entry type: Application example Entry ID: 20987711, Entry date: 03/29/2005

FDL communication with SDA service via PROFIBUS CPs and Send/Receive interface

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A common task in automation systems is the quick and efficient transmission of small or medium-sized amounts of data between two stations via PROFIBUS.

FDL communication (Field bus Data Link) is a standardized and efficient possibility for quick data exchange between different types of CPUs (using suitable communication processors). The Application Example presented here offers the user a quick and practical introduction to the specific features of the SDA service (Send Data with Acknowledge) within the FDL protocol and it provides an insight in the SIMATIC-specific configuration and user interface (AG_SEND/AG_RECV).

The following picture illustrates the hardware configuration of this example

The example shows in particular how consistent transmission of larger user data sets of 1024 bytes can be realized by breaking down each data set into five partial data sets of max. 240 bytes (maximum user data size when using FDL-SDA). These partial data sets are transmitted successively via FDL communication to the receiving station where they are recombined again in their correct order.

This principle is  illustrated in the following scheme.


Content of Downloads


Documentation (German)
Data Transmission via FDL Connection with SDA Service Using AG_SEND / AG_RECV 
20987711_FDL_SDA_DOKU_v10_d.pdf ( 558 KB )
Documentation (English)
Data Transmission via FDL Connection with SDA Service Using AG_SEND / AG_RECV 
20987711_FDL_SDA_DOKU_v10_e.pdf ( 522 KB )
Code  20987711_FDL_SDA_CODE_v10.zip ( 469 KB )





05/2004 first edition

Broadcast, Multicast, NetPro, AG_SEND, AG_RECV, CP 443-5 Basic, CP 342-5

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