一、前言工业控制机是国内近年来推出的新产品,较常见的是STD总线工业控制机,它是对工业生产过程现场实时控制管理设备,它同时也需要将一些数据和结果打印出来。但目前击打式打印机打印速度慢,约为80CPS(字符/秒),因此在打印过程中,主机将无法进行其它工作,较长时间脱离现场控制,这种失控情况在很多生产中是不允许的。为了克服这个缺点,使主机将要打印的数据迅速无误地传送给打印机,而主机还能 I. Introduction The industrial control machine is a new product introduced in recent years in China. The most common one is the STD bus industrial control machine. It is a real-time control and management device for the industrial production process. It also needs to print some data and results. However, at present, impulse printers print at a slow speed of about 80CPS (characters per second), so during the printing process, the host will not be able to perform other tasks and leave the field control for a long time. Such uncontrolled situations are not allowed in many production of. In order to overcome this shortcoming, make the data that the host computer want to print to convey to the printer promptly and without error, but the host computer can