Due to many PLC manufactories, many company has special net communication means, many kinds of PLC can not compatible, there has no definite standard.

• 但是PLC的生产厂家众多，各公司都有自己专用网络通讯手段，各种机型互不兼容，没有明确一致的标准，在编程元件的种类、数目、编程语言等方面各不相同，互不兼容。