基于DI的低成本艾默生PLC模拟量采集法

Low-cost Analog Signal Acquisition for Emerson PLC Based on DI

PLC测控系统中大量用到模拟量,普遍的解决方案是采用与之配套的原厂模拟量采集模块,这种做法导致系统应用成本居高不下;为此,提供了一种基于DI(开关量输入)输入方式的采集方案,并以艾默生EC20系列PLC为例做了详细的介绍,包括模拟量采集模块的构成、与EC20系列PLC的连接方法、通讯数据包格式、通讯协议、数据采集模块的数据上传程序以及EC20系列的接口程序;本方案与传统方案比较,应用成本大幅度降低,经几年数千例的实际工程应用,证明性能稳定可靠。

In order to realize a large number of analog used in PLC measurement and control System, generally analog acquisition modules of ancillary company are adopted, but this solution leds to high cost of system application. Therefore in the paper we adopt the acquisition method based on DI （digital input） and introduce it with Emerson EC20 series PLC, including the structure of analog acquisition module and communication with EC20 series PLC, and communication data packet format and protocol, and data upload procedure of data acquisition module and interface procedure of EC20 series. Compared to traditional programs, the application cost of the program we adopt is reduced greatly and through several thousands practical engineering applications it is proved that performance is stable and reliable.