USSI Microlok II Functional description
Page 4 of 27 July 2005 UM-6800A Rev1.3
1.1. INTRODUCTION
This manual provides the following information about the Microlok II system.
•
System level application and operational descriptions
•
System component specifications
This manual is to be referred in conjunction with the Microlok II service
manual SM6800A.
2.1. SYSTEM OVERVIEW
The Microlok II system operation is controlled by proprietary executive
software running on the system hardware. The user application logic is
written in a proprietary Microlok II programming language and is compiled by
a proprietary compiler into a set of data tables which are interpreted by the
executive software during run-time.
The high-level block diagram of the Microlok II system is shown below. The
system uses diversity and self-checking concepts in which critical operations
are performed in diverse ways, using diverse software operations and critical
system hardware is tested with self-checking operations. Permissive outputs
are allowed only if the results of diverse logic operations correspond and the
self-checks reveal no failures. It uses a combination of vital and non-vital
hardware, and an executive software performing critical operations on the
site-specific application logic tables using dual-path processing and double
storage techniques along with continuous monitoring of the hardware
through the use of extensive built-in diagnostics. Any failure in any critical
portion of the equipment will result in the controlled system returning to a
safe state.
