Speaking of library instructions, I believe everyone is familiar with the three words "library instructions"! Library instructions are often used whether you are learning PLC or using PLC programming, but sometimes you need to create library instructions yourself. Why do you need to create library instructions yourself? When we are programming, we often need to call a certain program repeatedly, and it is very troublesome to write it every time. At this time, we need to make this program into a library instruction so that we can call it repeatedly. Well, without further ado, let's analyze it in detail.

01 Programming Procedure

Step 1: (Open STEP7-MicroWIN SMART programming software on the desktop)

Step 2: (Create variables in the subroutine (SBR))

Here is an example of creating a library file for the start-stop program

Create variables in the variable table

Symbol: Start Variable type: IN Data type: BOOL

Symbol: Stop Variable type: IN Data type: BOOL

Symbol: Run Variable type: OUT Data type: BOOL

Automatically create an address after selecting the data type

Step 3: (Write the start-stop program in the subroutine and fill it in with the variables created in step 2)

Step 4: (Change the subroutine name, select SBR-0 with the mouse, right-click Properties - General - Modify the name, here change it to Start Protection Stop Warehouse Instruction)

Warm reminder: If you do not change the subroutine name when creating a library instruction, an error will be reported and prompted (placing this instruction requires creating one or more POUs).

Step 5: (Select the library in the project tree on the left side of the programming software and right-click to select Create Library. After opening, enter the library name, click the Next Component, select the Start-Protection-Stop Library Instruction, and click Add. You will see that the Start-Protection-Stop Library Instruction has been successfully added on the right. At this time, keep clicking Next until the Create step and click Create. Look at the output window and the library file is created successfully.)

02 Call library instructions

Step 1: (After restarting the STEP7-MicroWIN SMART programming software, you will see the library instruction name created previously in the project tree library instruction on the left)

Step 2: (Call the start-protection and stop-warehouse instruction in the main program and fill in the corresponding pins)

03 Monitor test library instructions

Step 1: (Download the program)

Step 2: (Monitor PLC and force I0.0, Q0.0 output from 0 to 1)