现场总线的发展与分歧从1984年美国Intel公司推出Bitbus标准开始,现场总线标准经历了十五年的发展过程。1985年美国Rosemount公司推出HART协议,在4～20mA模拟信号的基础上叠加数字信号。1992年美国的Fisher-Rosemount公司、Foxboro公司,德国的Simens、H&B公司,日本的横河、NEC等公司成立了 Fieldbus development and divergence From the United States in 1984, the company introduced Bitbus standard Intel, the field bus standard has undergone a 15-year development process. In 1985 the United States introduced Rosemount HART protocol, 4 ~ 20mA analog signal based on the superimposed digital signal. In 1992, Fisher-Rosemount, Foxboro, Germany’s Siemens, H & B, Japan’s Yokogawa, NEC and other companies were established