ABB SD812F 3BDH000014R1 控制模块 DCS PLC系统

ABB SD812F 3BDH000014R1 控制模块 DCS PLC系统

ABB SD812F 3BDH000014R1 控制模块 DCS PLC系统

ABB SD812F 3BDH000014R1中心处理单元(CPU)是可编程逻辑操控器PLC的操控。它依照PLC体系程序赋予的功用接收并存储从编程器写入的用户程序和数据;查看电源、存储器、I/O以及警戒定时器的状态，并能诊断用户程序中的语法错误。

当PLC投入运转时，ABB SD812F 3BDH000014R1它以扫描的方式接收现场各输入设备的状态和数据，并分别存入I/O映象区，然后从用户程序存储器中逐条读取用户程序，经由指令解释后按指令的规定履行逻辑或算数运算的结果送入I/O映象区或数据寄存器内。等所有的用户程序履行完毕之后，后将I/O映象区的各输出状态或输出寄存器内的数据传送到相应的输出设备，如斯轮回运转，直到休止运转。

ABB SD812F 3BDH000014R1为了进一步进步可编程逻辑操控器的可靠性，近年来对大型可编程逻辑操控器还选用双CPU构成冗余体系，或选用三CPU的表决式体系。这样，即使某个CPU发作故障，整个体系仍能正常运转。

ABB SD812F 3BDH000014R1 控制模块 DCS PLC系统

The ABB SD812F 3BDH000014R1 Central processing unit (CPU) is the control of a programmable logic controller PLC. It receives and stores user programs and data written from the programmer according to the function given by the PLC system program; View the status of power, memory, I/O, and alert timers, and diagnose syntax errors in user programs.

When the PLC is put into operation, ABB SD812F 3BDH000014R1 receives the status and data of each input device in the field by scanning, and stores it into the I/O image area respectively, and then reads the user program one by one from the user program memory. The result of logic or arithmetic operation performed according to the instruction is sent to the I/O image area or data register after instruction interpretation. After all the user programs are completed, the data in each output state or output register in the I/O image area is transmitted to the corresponding output device, and the cycle runs as follows until the operation stops.

ABB SD812F 3BDH000014R1 In order to further improve the reliability of programmable logic controllers, in recent years, dual cpus are also used to form a redundant system for large programmable logic controllers, or a three-CPU voting system is used. In this way, even if a CPU fails, the whole system can still operate normally.