西門子S7系列可編程控制器分為S7-400、S7-300、S7-200三個(gè)系列，分別為S7系列的大、中、小型可編程控制器系統(tǒng)。S7-200系列可編程控制器有CPU21X系列，CPU22X系列，其中CPU22X型可編程控制器提供了4個(gè)不同的基本型號(hào)，常見(jiàn)的有CPU221，CPU222，CPU224和CPU226四種基本型號(hào)。
l L 通用裝入指令
l L STW 將狀態(tài)字寄存器的內(nèi)容裝入到累加器1
l LAR1 AR2將地址寄存器2的內(nèi)容裝入到地址寄存器1
l LAR1 將32位的長(zhǎng)整數(shù)裝入到地址寄存器1
當(dāng)CPU 的狀態(tài)由停止態(tài)轉(zhuǎn)入運(yùn)行態(tài)時(shí)，操作系統(tǒng)都調(diào)用OB100。當(dāng)OB100運(yùn)行結(jié)束后，操作系統(tǒng)調(diào)用OB1。
利用OB100先于OB1執(zhí)行的特性，可以為用戶主程序的運(yùn)行準(zhǔn)備初始變量或參數(shù)。
狀態(tài)字的位8稱為二進(jìn)制結(jié)果位。它將字處理程序與位處理聯(lián)系起來(lái)，在一段既有位操作又有字操作的程序中，用于表示字操作結(jié)果是否正確（異常）。將BR位加入程序后，無(wú)論字操作結(jié)果如何，都不會(huì)造成二進(jìn)制邏輯鏈中斷。在LAD的方塊指令中，BR位與ENO有對(duì)應(yīng)關(guān)系，用于表明方塊指令是否被正確執(zhí)行：如果執(zhí)行出現(xiàn)了錯(cuò)誤，BR位為0，ENO也為0；如果功能被正確執(zhí)行，BR位為1，ENO也為1。

Siemens S7 Series Programmable controllers are divided into S7-400, S7-300 and S7-200 series, which are the large, medium and small programmable controller systems of S7 Series. S7-200 series programmable controllers include cpu21x series and cpu22x series, of which cpu22x programmable controller provides four different basic models, including cpu221, cpu222, cpu224 and cpu226.
L l general load instruction
L l STW loads the contents of the status word register into accumulator 1
L lar1 ar2 loads the contents of address register 2 into address register 1
L lar1 loads a 32-bit long integer into address register 1
When the state of CPU changes from stop state to running state, the operating system calls ob100. When ob100 runs, the operating system calls ob1.
Using the feature that ob100 executes before ob1, initial variables or parameters can be prepared for the operation of the user's main program.
Bit 8 of the status word is called the binary result bit. It links word processing program with bit processing, and is used to indicate whether the result of word operation is correct (abnormal) in a program with both bit operation and word operation. After adding br bit into the program, no matter what the result of word operation is, it will not cause binary logic chain interruption. In the block instruction of lad, the br bit has a corresponding relationship with Eno, which is used to indicate whether the block instruction is correctly executed: if there is an error in execution, the br bit is 0, and eno is also 0; If the function is performed correctly, the br bit is 1 and eno is also 1.