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Entry type: FAQ, Entry ID: 76278125, Entry date: 07/04/2013
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What options does the S7-1500 provide for downloading data in RUN?

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Description The CPU modules of the S7-1500 series behave differently to CPU modules of the S7-300/400 series when downloading software changes. For example, you have the option of downloading changes in STOP and in RUN without affecting the current values of tags already loaded. You can extend the interfaces of function blocks or data blocks in running operation and change operating STEP 7 programs that are already running error-free on a plant. ...

Description
The CPU modules of the S7-1500 series behave differently to CPU modules of the S7-300/400 series when downloading software changes. For example, you have the option of downloading changes in STOP and in RUN without affecting the current values of tags already loaded. You can extend the interfaces of function blocks or data blocks in running operation and change operating STEP 7 programs that are already running error-free on a plant.

If you want to download the changes in global data blocks or interfaces of function blocks into the CPU without overwriting the current values, in the TIA you must enable the memory reserve in the "Settings" for that block. All tags that you then declare are put in the memory reserve. When you then download, the values of tags already downloaded are not affected. The hardware and software requirements below must be fulfilled for the "Download without reinitialization" function:

  • From STEP 7 (TIA Portal) V12 onwards
  • CPUs of the S7-1200 and S7-1500 series with STEP 7 (TIA Portal) V12+SP1 onwards
  • The blocks were created by the user (no supplied blocks from the library).
  • Blocks with optimized access. (Default setting for newly created DBs from STEP 7 V12 onwards).

We describe the following topics in this entry.

Enabling the memory reserve for newly created data blocks and for non-retentive memory areas
 

No. Procedure
1 Each function block and data block receives a preset reserve of 100 bytes. If you want to change this memory reserve, you select the menu command "Options > Settings" from the menu bar to open the "Settings" dialog in the working area.
2 In the area navigation you open the "PLC programming" folder and click "General".
3 Under "Download without reinitialization" you define the memory reserve for all the newly created function blocks and data blocks.

After downloading, the memory reserve for blocks is 100% in the main memory of each CPU even if the reserve is not being used. Even in the case of the reserve in the retentive memory the value set is reserved 100% in the retentive memory. In the case of smaller CPU modules with less memory area you should be cautious when selecting this default value, because not all data blocks need a reserve of 500 bytes.


Fig. 01

Notes

  • This reserve does not apply for retentive memory areas.
  • Existing blocks are not taken into account in this change.
4 Save and compile your project settings. To compile, you right-click "Program blocks" in the project navigation and choose "Compile > Software (changes only)" in the context menu.
5 The project or the blocks should have been downloaded consistently beforehand. For safety's sake we recommend that you check this using the menu command "Tools > Compare > Offline/Online".
6 Open the block that you want to edit and then click the "Download without reinitialization" button in the toolbar. All the newly declared tags in this data block are now stored in the enabled memory reserve and can be downloaded without affecting the running process.


Fig. 02 

Note
If you have already enabled the "Download without reinitialization" function, you cannot change the size of the memory area. In this case you must disable the function beforehand. In the block you once again click the "Download without reinitialization" button (Fig. 02). Disabling the memory reserve however implies initializing the complete DB area for the next download regardless of whether you have declared retentive or non-retentive tags.

7 Acknowledge the next message with OK and declare the additional tags in your data block.

Note
The maximum limit value of the general and retentive memory reserves is 2 MB (= 2097152 bytes). If this value is exceeded, it is not possible to download.

8 Save and compile your program as described under point 4 and using the menu command "Download to device > Software (changes only)" download the changes into the S7-1500 CPU. After downloading, only the newly added tags are initialized with the defined start values. The current values of the tags already online remain unchanged.
Table 01

Enabling the memory reserve for single data blocks and for retentive memory areas
 

No. Procedure
1 In the project navigation you right-click the data block and open the "Properties" in the pop-up menu that opens.
2 Select the "Download without reinitialization" tab and enable the "Enable download without reinitialization for retentive tags" option.
3 Enter the required number of bytes in the "Retentive memory reserve" field. If necessary, you can change the general memory reserve in the appropriate input field. A value of 100 bytes is entered by default by the system.

The general memory reserve and the reserve in the retentive memory are added together for the overall reserve. In the example in Fig. 03, therefore, we have an overall reserve of 250 bytes.


Fig. 03

4 Close the dialog with OK and open the data block.
5 Click the "Download without reinitialization" button and declare the additional tags in your data block. All the newly declared tags in this data block are then stored in the enabled memory reserve and can be downloaded without affecting the running process.

Note
Existing variables can no longer be deleted and their properties no longer changed (except default value, start value and comments). Only the tags that you have stored in the memory reserve can be deleted.

6 Save and compile your project settings. To compile, you right-click "Program blocks" in the project navigation and choose "Compile > Software (changes only)" in the context menu.

Note
If there is not enough memory reserve, compilation is aborted with an error message. In this case you must change the memory reserve as described in point 3.

7 Download the program changes into the S7-1500 CPU using the menu command "Download to device > Software (changes only)". After downloading, only the newly added tags are initialized with the defined start values. The monitoring values of the tags already online remain unchanged.
Table 02

Downloading the program changes with reinitialization
If you want to once again download program changes with reinitialization, you must move the tags from the memory reserve once again into the regular memory area.
 

No. Procedure
1 Open the data block and click the "Download without reinitialization" button (Fig. 02) to disable the memory reserve.
2 You then get the message "Changes in RUN require a reinitialization". Acknowledge this message with "OK".
3 Right-click "Program blocks" in the project navigation and choose "Compile > Software (reset memory reserve)" in the context menu.

Note
When compiling using the menu command "Software (reset memory reserve)" and subsequently downloading ("Software changes only"), the complete DB (even the part that is not in the reserve with the retentive tags) is initialized.

4 Acknowledge the subsequent message with "OK".
5 Load your project into the CPU. The tags are then re-initialized.

Note
Using the menu command "Online > Load PLC program in device and reset" all the changed and unchanged blocks are loaded into the CPU. This resets all the values (including the retentive values) back to their initial values.

Table 03

Further Information
More information is also available in the STEP 7 TIA Portal Online Help under "Loading block extensions without reinitialization".

Creation environment
The screens in this FAQ response were created with STEP 7 (TIA Portal) V12.

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