Introduction
The Siemens TIA Portal platform is an advanced software development platform for modern automation control systems. In this software platform, data blocks are important elements used for storing data.
What are Optimized and Standard Data Blocks
In Siemens TIA Portal, data blocks are important structures for storing program data, where the main difference between optimized and standard data blocks lies in memory management. Optimized data blocks are arranged in a fixed byte order, while standard data blocks are arranged according to the CPU architecture and operating system’s automatically determined byte order.
Optimized data blocks are the default and recommended setting for S7-1200/1500, and are not suitable for S7-300 or S7-400. To maintain compatibility with older projects, users must manually select the “Standard – Compatible with S7-300/400” option when creating.
“Optimized Data Block” refers to “Optimized DB Block,” while “Standard Data Block” refers to “Standard DB Block.”
○ Storage Method Comparison ○
In the S7-1200 CPU, standard DB blocks and optimized DB blocks are stored in the PLC as shown in the following diagram.
In the S7-1500 CPU, standard DB blocks and optimized DB blocks are stored in the PLC as shown in the following diagram 04.
In the S7-1500 CPU, compared to standard DB blocks, optimized DB blocks provide faster access speeds, primarily due to the CPU’s encoding method, as shown in the following diagram:
○ Comparison of Optimized and Standard Data Blocks ○
When adding a DB block in TIA Portal V12 for S7-1200/S7-1500 CPUs, its default property is an optimized DB. The overall comparison between optimized DB blocks and standard DB blocks is shown in the following table:
The comparison of DB parameters between S7-300/S7-400 and S7-1200/S7-1500 is shown in the following table:
By modifying the properties of the DB block, it can be changed to a standard DB block or an optimized DB block, as shown in the following diagram:
If the DB block property is a standard DB block, the absolute addresses of the variables within that DB block will appear after compilation. The comparison between standard DB blocks and optimized DB blocks is shown in the following diagram:
○ Advantages of Optimized Data Blocks ○
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Optimized data blocks are automatically saved in the available memory area of the block, thus eliminating gaps in memory. This optimizes memory capacity usage and prevents memory loss compared to standard data blocks.
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You can create optimized data blocks with any structure without worrying about the physical arrangement of individual tags.
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You can define specific individual tags as retainable. In standard data blocks, you can only define the entire block as retainable.
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Since optimized data blocks are arranged in a fixed byte order, accessing their data is faster than accessing standard data blocks.
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Optimized data blocks can be accessed by name, eliminating the need to determine the position of each data type by offset, making programming simpler and more intuitive.
When to Use Standard Blocks?
When you need to interact with older protocols or external devices that only recognize “absolute addresses,” such as:• Performing S7 unilateral communication (PUT/GET)• Connecting to older HMI versions like WinCC V7.2• Allowing OPC servers to read data
Aside from these “exception cases,” in S7-1200/1500, optimized blocks are your only choice! Use them boldly without hesitation.
Siemens PLC Wireless Communication Solution Sharing
This solution uses WinCC and two Siemens S7-1200 PLCs as an example to implement wireless Ethernet communication under the Modbus TCP/IP protocol.
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