PC's Printer Port as an Interface for Astronomy Instrument

Astronomical instruments today have been digitalized,therefore an interfacc is always needed.In the early of 2001,we began to set up several instruments for site testing.These instruments include a Differential Image Motion Monitor,a photometer for photo-counting,and a CCD camera. Under the condition of the site survey,this set of instruments should be compact,handiness,and the power supply used should be batteries. It seems to be the best choice to use a laptop as the control computer.Unfortunately,the interface card can not be put into the notebook computer,in this case the PRN port comes to be the choice. The printer port is an interface that comes with each PC,and we find that it is suitable for astronomical applications.Our photometer and CCD are connected to the computers by the PRN port,and the photometer is in SPP mode and the CCD camera is in EPP mode. In this paper,the concept of SPP and EPP is described,and a brief introduction of SPP and EPP programming is given.The details in our design are illustrated in this paper.The operation system of our laptop is Windows 98,and our software is developed with the Microsoft Visual C++6.0.