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Entry type: FAQ Entry ID: 109760539, Entry date: 10/23/2018
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How do you disable the SNMP on the SIMATIC PCS 7 CPU 410?

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Under certain circumstances it is useful to disable the SNMP function of a SIMATIC PCS 7 CPU 410. This might be the case if the security policy in your network does not permit the use of SNMP or if you are using your own SNMP solution via your own communication instructions, for example.

With the firmware version V8.2.1 you can disable the SNMP function of a SIMATIC PCS 7 CPU 410.
To disable SNMP for the interface integrated interfaces of a SIMATIC PCS 7 CPU 410 we provide a solution that you can integrate into your project. With this solution you can very easily disable or enable the SNMP function of the CPU 410.

However, be aware that by disabling the SNMP function of a device various options for diagnosis of the network topology (via the PRONETA tool or via a SINEMA server) are no longer available.


Function description 
Part of the solution are the blocks "dis_SNMP" (UDT2553), "SNMP_EN_DIS" (FB2553) and "WRREC" (SFB53). The SFB "WRREC" (SFB53) is parameterized and called in the "SNMP_EN_DIS" block. The data structure of the data record B071H is also required for the parameter assignment.
This data structure is shown in the UDT "dis_SNMP". When you call the parameterized SFB "WRREC" the data record is transferred to the PROFINET interface X5 or X8 (addressed via ID) of the SIMATIC PCS 7 CPU 410.
This leads to disabling or enabling of the SNMP function.

The following project includes the required blocks:
 Registration required snmp_dis.zip (99.5 KB)
 
Procedure for disabling the SNMP function
1. Dearchive the "snmp_dis" project and copy the blocks "dis_SNMP" (UDT2553),
    "SNMP_EN_DIS" (FB2553) and "WRREC" (SFB53) in block folder of your PCS 7 projects.


2. Create a new CFC chart

3. Drag the "SNMP_EN_DIS" block into the CFC chart.



3. The input parameter "snmp_on" must have the value 0 to disable the SNMP function.
    If you want to enable the SNMP function again, then you set the value of this parameter to 1.

4. To the parameter "log_b_addr" you assign the logical base address of the internal PROFINET interface X5 or X8.

5. In the sequence editor you assign the "SNMP_EN_DIS" block to the OB100 (warm restart).  

6. Repeat steps 2 to 4 for a redundant H system. In the sequence editor you assign the block to the OB72 (CPU redundancy error).

5. Compile the changes and load them into the PLC. The next time the OB100 or OB72
    is called the SNMP function is disabled or enabled. 

Note

  • Enabling and disabling always take place for both PN interfaces (X5 and X8) together.
  • After the following actions the SNMP is enabled again and is disabled automatically via OB100 or OB72.
  • Switch the CPU power on and off
  • Reset the CPU
  • Reset CPU to factory settings
  • Reboot the CPU

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit
https://www.siemens.com/cybersecurity#Ouraspiration.