University Laboratory Automatic Test System And The Interface Between Masters And Slaves

Automated Test System (ATS) is an important stage in the growing of automatic test technology. The idea of virtual instrument is widely adopted in modern automated test system. That is, the same set of instruments is able to accomplish different kinds of tasks without any change to the hardware, as long as such abilities are supported in software. By using PC, data acquired can be processed in many complex ways as well as be shown in different styles, such as in chart, in file, and so on. It is a factual and meaningful task to design an automated test system for college laboratories so as to free experimenters from tiring and meaningless labor.Design of automated test system is becoming more and more standardized, universal and open. The automated test system for college laboratories is not only required to have the ordinary characteristics of auto-measuring system, but also demanded to meet the limited outlay and the factual conditions of college laboratories. Once necessary capabilities are achieved, it is acknowledged to reduce the cost as low as possible. Considering this, we choose GPIB bus to build this system. Host machine in the system is PC, which the labs already have. And slave machines are GPIB instruments using 89C51 SCM as microprocessor. In this system data-processing is mainly carried by PC.Dependable and prompt communication between host-machine and slave-machines is one key aspect of this system. After careful comparison and reasoning we decide to use parallel print port under EPP mode to design the GPIB interface board for PC. This board is outside the PC, so as to avoid inserting into and drawing out of PC box. That is convenient to the users. Just joined the slave-machines with this simple board, any PC equipped with out software can act as the host-machine in making up an automated test system.In this paper, firstly, the global architecture of system is presented. Then system's demands on the interface are analyzed. After the comparison of present connecting manners, the communication solution in this system is presented. It is using parallelprint port to realize GPIB communication. This solution is reasoned thoroughly and both software and hardware design of the communication solution are presented in detail. At the end of this paper, there is an example in use.