功能块(FB,FC)实际上是用户子程序，可以分为带记忆的功能块和不带记

Function blocks (FB, FC) are actually user subroutines, which can be divided into function blocks with memory and function blocks without memory FC. The former has a backup data block (INTANCE DATA BLOCK) corresponding to it, and the backup data block It is a data block whose data structure is exactly the same as the parameters of this function block. The data stored in the backup data block continues to be retained at the end of the FB, so it is called "memory". The function block FC has no backup data block, and the data cannot be retained after the FC completes the operation. The S7 200 CPU also provides standard function blocks (SFB, SFC), which are pre-programmed and integrated into the function library of the S7 200 CPU after testing. Users can call them directly to compile their own programs efficiently. Since they are part of the operating system program, there is no need to download them to the PLC. Similar to FB, SFB requires a backup data block and installs the DB block into the CPU as part of the program.

Function block (FB, FC) is actually a user subroutine, can be divided into a memory function block and a function block WITHout memory FC. The former has a backup data block (INTANCE DATA BLOCK) corresponding to it, the backup block is a data structure and the function block parameters of the same block of data block. The data stored in the backup block continues at the end of the FB, so it is called "memory". Function block FC does not have a backup block, and the data cannot be maintained when the FC completes the operation. The S7 200 CPU also offers standard function blocks (SFB, SFC), which are pre-programmed and tested integrated in the S7 200 CPU's function library. Users can call them directly and efficiently prepare their own programs. Because they are part of an operating system program, you don't have to download them to the PLC. Similar to FB, the SFB requires a backup block and installs the DB block into the CPU as part of the program.

Function block (FB, FC) is actually a user subroutine, which can be divided into function block with memory and function block without memory. The former has a backup data block corresponding to it, and the backup data block is a data block whose data structure is exactly the same as the parameters of the function block. The data stored in the backup data block remains at the end of FB, so it is called "memory". Function block FC has no backup data block, and the data cannot be maintained after FC completes the operation. S7 200 CPU also provides standard function blocks (SFB, SFC), which are programmed in advance and integrated into the function library of S7 200 CPU after testing. Users can call them directly, and write their own programs efficiently. As they are part of the operating system program, they do not need to be downloaded to PLC. Similar to FB, SFB needs a backup data block, and DB block is installed in CPU as part of the program.<br>