Problem
Monitoring and regular control of network components allow us to get a complete overview of the status and availability of an industrial network. It is important to be able to monitor and, if necessary, change the factors that influence them. In this entry, the following requirements are to be met:

• Providing also S7 CPUs with an option to control the network components
• Controlling the digital I/O of a new SCALANCE W748-1 RJ45 IWLAN component using network management functions. This function can be used to deliberately switch off specific plant sections of, for example, monorail conveyors.

Solution  
Network management systems monitor and, if necessary, control the status of SNMP-capable network components via SNMP (Simple Network Management Protocol). The blocks of the "SNMP_Library" and the applications now allow you to use a SIMATIC S7 CPU with PROFINET interface to poll all desired information from network components and, if necessary, control them.

The diagram below shows a network where the S7 CPU controls different network components.

In the download area, three documents are available that deal with the topic of this entry.

SNMP library for STEP 7 5.5

• The library contains all necessary blocks for reading and writing SNMP variables for S7 CPUs with integrated PROFINET interface.

Simple application example of the SNMP library

• The application example shows you how to use the blocks of the SNMP library in order to read and write different SNMP variables from SCALANCE switches from the S7 CPU.
• The example was created in FBD.

SNMP control block for control and status check of the digital IO of a SCALANCE W748-1 IWLAN client

• This application example shows the programming of a block that can read and switch the digital output of a SCALANCE W748-1 RJ45 with the aid of the SNMP library.
• The user block was created in SCL.

Downloads

Content of Downloads	Download
Documentation  Description of the SNMP library for S7 CPUs with PROFINET interface
Code  Block library for STEP 7 V 5.5
Documentation  Description of the simple application example to use the SNMP library
Code  STEP 7 project (V 5.5) for the simple application example
Documentation  Description of the control block to control the digital output of a SCALANCE W786-1 RJ45
Code  STEP 7 project (V 5.5) for the control block

Note on security
Caution
The functions and solutions described in this entry predominantly confine themselves to the realization of the automation task. Please also take into account that corresponding protective measures have to be taken in the context of Industrial Security when connecting your equipment to other parts of the plant, the enterprise network or the Internet. For more information, please refer to Entry ID 50203404.

Last modification
The Library blocks SNMP_GET (FB 100) and SNMP_SET (FB 101) have been changed.