Introduction

The GBT Metrology system consists of many embedded systems, known as ZYs [1], that are controlled by a master process known as the ZIY. The ZY is the actual distance measuring system that uses a laser beam to accurately measure a range to a retro reflector. The ZY is in turn controlled by the ZIY, which coordinates the actions of the ZYs to provide a complete metrology system. The ZIY provides an ONC RPC interface to allow a client process (the ZIY Client) to control the ZIY. The ZIY Client may be a different process on the same host computer as the ZIY, or another process on another host computer anywhere on a TCP/IP network (see figure 2.1.)