外文翻譯--可編程控制器-其他專業(yè)-文庫吧資料
2025-01-27 10:01本頁面
【正文】 and humidity. Third, PLCs are easily maintained by plant technicians. Basic PLC hardware architecture The basic architecture of a PLC consists of main ponentsthe processor module, the power supply, and the I/O modules. The processor module consists of the central processing unit (CPU) and memory. In addition to a microprocessor, the CPU also contains at least an interface to a programming device and may contain interfaces to remote I/O and other munication works. The power supply is usually a separate module, and the I/O modules are separate from the processor. The types of I/O modules include discrete (on/off), analog (continuous variable), and special modules like motion control or highspeed counters. The field devices are connected to the I/O modules. Depending on the amount of I/O and the particular PLC processor, the I/O modules may be in the same chassis as the processor and/or in one or more other chassis. Up until the late 1980s, the I/O modules in a typical PLC system were in chassis separate from the PLC processor. In the more typical presentday PLC, some of the I/O modules are present in the chassis that contains the processor. Some PLC systems allow more than one processor in the same chassis. Smaller PLCs are often mounted on a DIN rail. The smallest PLCs (often called microPLCs or naonPLCs) include the power supply, processor, and all of the I/Os in one package. Some microPLCs contain a builtin operator interface panel. For many microPLCs, the amount of I/O is limited and not expandable. Basic software, memory architectur
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