SIMATIC S7-300 PLC S7-300是模塊化小型PLC，能中等性能要求的應(yīng)用。各種單獨的模塊之間可進行廣泛組合構(gòu)成不同要求的。與S7-200 PLC比較，S7-300 PLC采用模塊化結(jié)構(gòu)，具備高速（0.6~0.1μs）的指令運算速度；用浮點數(shù)運算比較有效地實現(xiàn)了更為復(fù)雜的算術(shù)運算；一個帶用戶接口的工具方便用戶給所有模塊進行參數(shù)賦值；方便的人機界面服務(wù)已經(jīng)集成在S7-300操作內(nèi)，人機對話的編程要求大大。SIMATIC人機界面（HMI）從S7-300中取得數(shù)據(jù)，S7-300按用戶的刷新速度傳送這些數(shù)據(jù)。S7-300操作自動地處理數(shù)據(jù)的傳送；CPU的智能化的診斷連續(xù)監(jiān)控的功能是否正常、記錄錯誤和特殊事件（例如：超時，模塊更換，等等）；多級口令保護可以使用戶高度、有效地保護其技術(shù)機密，防止未經(jīng)允許的和修改；S7-300 PLC設(shè)有操作選擇開關(guān)，操作選擇開關(guān)像鑰匙一樣可以，當(dāng)鑰匙時，就不能改變操作，這樣就可防止或改寫用戶程序。具備強大的通信功能，S7-300 PLC可通過編程Step 7的用戶界面提供通信組態(tài)功能，這使得組態(tài)非常容易、簡單。S7-300 PLC具有多種不同的通信接口，并通過多種通信處理器來連接AS-I總線接口和工業(yè)以太網(wǎng)總線；串行通信處理器用來連接點到點的通信；多點接口（MPI）集成在CPU中，用于同時連接編程器、PC機、人機界面及其他SIMATIC S7/M7/C7等自動化控制。
SIMATIC S7-300 PLC S7-300 is a modular Small PLC, which can be used in applications with medium performance requirements. Various individual modules can be widely combined to form different requirements. Compared with S7-200 PLC, S7-300 PLC adopts modular structure and has high speed (0.6~0.1 μ s) Instruction operation speed; More complex arithmetic operations are effectively realized by floating-point operations; A tool with user interface is convenient for users to assign parameters to all modules; Convenient man-machine interface service has been integrated into S7-300 operation, and the programming requirements of man-machine dialogue are greatly increased. SIMATIC human machine interface (HMI) obtains data from S7-300, which transmits these data according to the user's refresh speed. S7-300 operation automatically processes the transmission of data; The intelligent diagnosis of CPU continuously monitors whether the function is normal, records errors and special events (such as timeout, module replacement, etc.); Multi level password protection enables users to highly and effectively protect their technical secrets and prevent unauthorized and modification; S7-300 PLC is equipped with an operation selection switch, which can be operated like a key. When the key is used, the operation cannot be changed, so as to prevent or rewrite the user program. With powerful communication function, S7-300 PLC can provide communication configuration function through programming the user interface of step 7, which makes the configuration very easy and simple. S7-300 PLC has a variety of different communication interfaces, and connects AS-I bus interface and industrial Ethernet bus through a variety of communication processors; The serial communication processor is used to connect point-to-point communication; Multipoint interface (MPI) is integrated in CPU, which is used to simultaneously connect programmer, PC, man-machine interface and other automation controls such as SIMATIC s7/m7/c7.