Fieldbus builds up interconnections among field instruments and field control units by providing a wholly digital , bi - directional and multi - variant communication path , which has no i only greatly improved the reliability and ability of anti - disturbance , but also sharply reduces the costs of installation and routine maintenance . can ( controller area bus ) belongs to the asynchronous communication network 现场总线使得现场仪表之间、现场仪表与控制设备之间构成网络互连系统,实现全数字化、双向、多变量的数字通讯,这大大地提高了系统的可靠性和抗干扰能力,同时节省了整个系统的投资、安装及后期维护费用。