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Entry type: Application example Entry ID: 109479553, Entry date: 07/06/2020

SIMATIC S7-1200/S7-1500 and SIMOTION: Acyclic Data Exchange

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The standard libraries LAcycCom for SIMATIC S7-1200/S7-1500 and LDPV1 for SIMOTION provide a collision-free coordination of communication resources in the CPU for acyclic data exchange via DPV1 services. Therefore the corresponding functions in these libraries have to be used in the application instead of the existing system functions for the communication with external devices.

A user application wants to communicate with external devices using acyclic data exchange e.g. to read the energy consumption value out of a device. There are limited resources available in the CPU for the communication handling via DPV1 services. If concurrent requests happen or the resources are exhausted then collisions and additional delays can occur. Because of this the communication throughput decreases. In addition the user has to evaluate the return values of the system functions and has to repeat the requests when the resources are available again. Therefore significant programming effort is necessary for the application engineer. 

The libraries for acyclic data exchange via DPV1 services are intended to utilize the limited communication resources in SIMATIC and SIMOTION CPUs in an optimal way and also to avoid collisions in data transfer. As a result the communication to external devices is handled reliable and as fast as possible.

For this the SIMATIC standard library LAcycCom is available and for SIMOTION the standard library LDPV1. The resources for acyclic data exchange are arbitrated between the requesting instances in the SIMATIC and SIMOTION CPU. The libraries are divided into general resource management and several higher level functions for different external devices already using the resource management. Therefore a communication with e.g. ET 200SP or SINAMICS devices is possible.

In addition functionality is provided to be able to use the resource manager also with user programmed blocks. This is strongly recommended when using any acyclic system functions like RDREC, WRREC and so on in the user application.

For easy handling of communication with drives compliant to PROFIdrive higher level functions are provided. These are already prepared to use the resource management for the acyclic data exchange via DPV1.

The following functions are available for drives compliant to PROFIdrive:

  • Read/Write parameters in the drive system
  • Activate/Deactivate complete drive objects
  • Activate/Deactivate components of drive objects
  • Saving of volatile RAM data into the retentive ROM memory (RAM2ROM)
  • Time synchronization of CPU and drive system to achieve a chronological order of alarms and messages

For implementing the SIMOTION version in SIMOTION SCOUT (STEP 7 V5.x) the LDPV1 software and manuals are included in the ProjectGenerator SIMOTION easyProject. The LDPV1 library and a prepared program for the global resource management (pGlobalBufferManager) are used e.g. by the SIMOTION module StartupCheck and will automatically be integrated into the project if this module is selected.
The library and the global resource management are therefore available for user applications.

ProjectGenerator: 51339107


STEP 7 Professional / Basic V15 (TIA Portal)
  For the usage in newer STEP 7 versions see corresponding system manuals (Compatibility of projects/PLC programs)

    SIMATIC S7-1200/S7-1500
        SIMATIC Manual DriveBasedFunctionalities 05/2020 (2,5 MB)
        SIMATIC Manual ResourceManagement 05/2020 (1,3 MB)
       Registrierung notwendig  LAcycCom SIMATIC V1.5.3 (2,7 MB)
       Registrierung notwendig  LAcycCom Example SIMATIC V1.5.0 (STEP 7 Professional only) (1,4 MB)


       Registrierung notwendig  LDPV1 SIMOTION V4.2.12 (9,0 MB)
      The manuals are included in the ZIP file

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