How does STEP7 use multiple instance data blocks? -Solutions - Huaqiang Electronic Network

SMD aluminum electrolytic capacitor

Single chip microcomputer STM32L151CCU6

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

Multiple data blocks are a special form of data blocks. For example, calling FB10 in OB1 and calling FB1 and FB2 in FB10, as long as the background data block of FB10 is selected as multiple instance data blocks, FB1 and FB2 do not need to be used. The instance data block is created, and its interface parameters are stored in multiple background data blocks of FB10. The method of creating multiple instance data blocks is as follows: In the data type option, just select "DB of the instance" in the data type option, as shown in the following example.

The following is a brief introduction to some considerations and methods for the use of multiple instance data blocks.

For example, plc controls two motors and the interface parameters for controlling both motors are the same. In general, we can write function block FB1 to control two motors. When controlling different motors, different motor blocks can be used to control different motors (for example, the control parameters of the first motor are saved in DB1, The control parameters of the second motor are stored in DB2. We can use DB1 as the background data when controlling the first motor to call FB1, and the second one also uses DB2 as the background data block). This requires the use of two background data, and if there are more motors to control, more data blocks will be used. The use of multiple instance data blocks is to reduce the number of data blocks.

In this case, we can use multiple instance data blocks to reduce the amount of data blocks used. In this case, we can call FB10 in OB1, and then call FB1 in FB10 (each motor is called once) to control the operation of the two motors. For each call, FB1 stores its data in the instance DB1 of FB1. This eliminates the need to allocate data blocks for FB1, all of which point to the data block DB10 of FB10. The schematic is as follows:

First, we need to insert a function block FB10 and a data block DB10, DB10 is a multiple background multiple data block of FB10. As shown below:

Second, you need to specify the instance data block it contains in FB10. The method is as follows: In the FB10 local variable definition window, after the name of each motor is controlled in the "STAT" variable area (must be in this variable area), the data type is selected as FB. After confirmation, then put Change to 1, which is the function block FB1. If you have already defined the symbol for FB1 in the variable table, its symbol name will appear automatically. The address is generally calculated automatically by the CPU based on the number of interface parameters of FB1. The default value is sufficient.

Because two motors are controlled, two such variables need to be defined in the STAT. The results are as follows:

After the above steps, the background data block DB10 of the FB completely contains the data required by the 1# and 2# motors, as shown in the following figure, wherein the address 2.0 to 8.0 is the interface area control parameter of the first motor, and 10.0 to 16.0 is the first Two motor interface zone control parameters.

At this time, two partial backgrounds that have been added appear in the "Multiple Instances" in the instruction list of FB10, as shown in the following figure.

In the program, you can call these two partial backgrounds to control the No. 1 and No. 2 motors. The procedure is as follows:

In this way, the 1# and 2# motors can be controlled separately by calling OB10 in OB1. As shown below: