NONIUS CAD4/MACH3 User manual

Introduction
Platforms
Terminal Interfaces
Terminals

Introduction

The CAD4-UNIX version was developed in 1994 for CAD4 users, who wanted to run their CAD4 on a UNIX platform. Until that time Nonius B.V. supported a VAX/VMS version (CAD4 express, CAD4 version 5.1) and a MSDOS version based on the CAD4 version 5.0. The Unix version is based on both versions, while the parts for the automatic procedure, strategy and display are based on the VAX/VMS program system ARGUS used at the University Utrecht.

This part of the manual  is not meant to replace the excellent technical manuals supplied by the manufacturers of the computer hardware components of CAD4 or MACH3 systems. It is assumed in this manual that the CAD4 operator is known as a user of the UNIX operating system. Here we restrict the discussion to enumerating the most common components and outlining their function in the system.

Platforms

At the moment the program has been tested on various types PC's (running under LINUX), and on Silicon Graphics workstations (IRIX), but in principle it should be running on all UNIX platforms.

For all CAD4 systems the diffractometer control is handled by an LSI 11/02, FALCON or FALCON+ microprocessor which resides in the Nonius interface. For the MACH3 systems the diffractometer is controlled by a 8051 processor. This microprocessor, hereafter referred to as the target cpu, which has its own 64 kb of MOS memory, minimizes the use of the host cpu. During data collection the host cpu is activated briefly only once per reflection.
 
 

Terminal Interfaces

To communicate with the various peripheral devices of a system, interface modules, which reside in the host computer, are necessary. In this context the Nonius interface (and thereby the CAD4 diffractometer) is just another peripheral device, which is treated as any other terminal.

In any CAD4 system the system console and the diffractometer control console can be the same physical device. Also, however, the diffractometer console can be linked to the interface and from the hosts point of view the interface comprise one device. The interconversion of serial and parallel data transmissions is the principal function of a terminal interface. This is because communications (I/0) within the computer occur by transmission and receipt of I/0 packets of bits all at once, while terminals require information one bit at a time. In addition to this minimal function of a terminal interface the speed of the transmission may be controlled and measures have been taken to ensure the integrity of the transmission.

Terminals

For CAD4 systems any terminal, conforming to the RS232C standard, can be used as the CAD4-terminal. It is linked to the system through the CT port of the Nonius interface. The communications rate between the Nonius interface and the CAD4-terminal is software selected by the CASPAR routine. The current CAD4-programs allow the use of any terminal connected to the host to control the diffractometer. For details on the communication see also the pages on Interaction with the Host Operating system and Starting and Stopping the CAD4 Programs.

For the ARGUS program (see Argus, Display of the CAD4 process) a graphics terminal is needed. For most common UNIX computer systems this is automatically available. For some LINUX versions the startx utility should be used in that case.