Siemens S7-200 PLC programming data movement instructions - Database & Sql Blog Articles

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The data loading, transfer and movement of the Siemens S7-200plc are all implemented by the MOV. The instruction format of the move instruction MOV in the ladder diagram is shown in Figure 10-4.1.
The MOV in the instruction is the mobile instruction code, B is the data length, and the data range allowed in the S7-200 is:
B: 1 byte (8-bit binary);
W: l word (16 bit binary):

DW: 2 words (32-bit binary):
R: Floating point number (32-bit binary).
In the instruction, IN: source data or data storage location;
OUT: Move the target position.
By changing the location of the moving source data and the location of the moving target, the MOV instruction can complete the loading, transfer and movement of data. When using MOV BIR, MOV-- BIW, you can move the direct input to the specified position or send the specified data directly to the output.
Indirect Addressing: The data source and moving target in the S7-200's move instructions can be not only constants, memory addresses, but also indirect addressing. In the case of indirect addressing, there are specific formats and requirements for the establishment of pointers and the designation of operands, and the scope of use thereof is also limited. For example, when establishing a pointer, the "&" mark should be added before the pointer address; when indirect addressing is used, the "+" mark should be added before the address pointer memory. For the S7-200 indirect addressing method, see the book. Chapter 8.
2. Data block movement
The data movement of the S7-200 can also be performed in "blocking". In this case, the programming instructions BLKMOV B (in bytes), BLKMOV-W (in words), and BLKMOV DW (in double words) should be used. The ladder program is shown in Figure 10-4.2.

The N in Figure 10-4.2 is used to specify the "block" size of the move. The executive program can move the 20-byte flag register data (MBIO~MB39) from MB10 to the 20-byte variable register from VB10. .
When Figure 10-4.2 uses the BLKMOV-W and BLKMOV_DW instructions, you only need to specify N as 10 and 5, and you can also move 20 bytes.
3. Data Loading and Transfer The so-called loading is essentially the operation of moving the specified data to the accumulator, so it can be implemented by moving instructions. On the S7-200, the data loading function can be realized by simply specifying the moving target position (OUT) as the accumulator 1 (ACl) in the MOV instruction.
The so-called transfer is essentially an operation of moving the contents of the accumulator to a specified position, and therefore, it can also be implemented by a move instruction. On the S7-200, you only need to directly command the data source location (IN) to accumulator 1 (ACl) to implement the data transfer function.