Function and application examples of PLC data transmission instructions

Data transfer instructions can realize the transfer and copy of data between storage units. Mitsubishi PLC (FX2N for example) has about 6 transfer instructions for users to use, and Siemens PLC (S7-1200 for example) has about 4 (mainly depends on whether they are strictly distinguished). This article uses examples to explain Mitsubishi PLC's MOV and Siemens 1200's MOVE in detail.

1. Transmitting command function

The transfer instruction can transfer data to a specified target. It has a wide range of uses: the transfer instruction can be used to clear storage units, start and stop devices such as motors, transfer data to data registers for data processing (such as addition, subtraction, multiplication and division calculations, etc.), and transfer data to digital displays for digital display, etc.

2. Application Examples

(I) Taking Mitsubishi FX2N PLC as an example

For example: There are 4 motors, driven by Y0, Y1, Y2, and Y3 respectively. The start signal is X4 and the stop signal is X5. Please use the MOV instruction to start and stop the motors at the same time.

1. Task analysis:

To complete the task using the MOV instruction, you need to understand the format used by the MOV instruction:

Note: K represents a decimal constant; H represents a hexadecimal constant; KnX…KnS is described by K1Y000: K1Y000 represents 4*1 consecutive bits starting with Y0, namely Y0, Y1, Y2, Y3; T represents a timer; C represents a counter; D represents a data register; V/Z represents an index register.

2. PLC control program

3. Program comments

K represents a decimal constant. After power-on, M8002 is turned on, the decimal number 0 is converted to the binary number 0000, and stored in the data register D12, so that D12 is cleared; when X004 is started, the decimal number 15 is converted to the binary number 1111, and stored in the 4 bits starting from Y0: Y0, Y1, Y2, Y3, so that the motor starts; X005 is turned on, the binary number 0000 in D12 is stored in Y0, Y1, Y2, Y3, and the motor stops.

(II) Taking Siemens S7-1200 PLC as an example

For example: There are 4 motors, driven by Q0.0, Q0.1, Q0.2, and Q0.3 respectively. The start signal is I0.1 and the stop signal is I0.0. Please use the MOVE instruction to start and stop the motors at the same time.

1. Task analysis:

The format used by the MOVE instruction is:

2. PLC control program

3. Program comments

QB0 represents a byte starting from address Q0.0 (B represents BYTE), namely Q0.7, Q0.6, Q0.5, Q0.4, Q0.3, Q0.2, Q0.1, Q0.0. When I0.1 is turned on, it starts, and the binary number 1111 from the transmission source is copied to the output terminal QB0, so that the values ​​of Q0.3, Q0.2, Q0.1, and Q0.0 are all 1, and the motor starts; when I0.0 is turned on, it stops, and the binary number 0000 from the transmission source is copied to the output terminal QB0, so that the values ​​of Q0.3, Q0.2, Q0.1, and Q0.0 are all 0, and the motor stops.

3. Appendix

1. S7-1200 transfer instruction MOVE schedule

2. Comparison table of two instruction formats