System and method for monitoring high speed data bus

Abstract

A system and method for monitoring messages containing command, status, and data words transmitted on a high speed, serial, asynchronous AS1773 fiber-optic data bus employing Manchester encoding includes a fiber-optical receiver connected to the data bus and adapted to receive and convert optical signals into message words containing either a command, a status, or a data word. The system also preferably includes a memory device having a number of storage locations adapted to receive and store the message words, which is organized in an optimal fashion to allow the system to monitor high speed data buses. Preferably, a logic device is operationally coupled to the fiber-optical receiver and adapted to serially receive and process each message word. The logic device controls the transfer of each message word into one of the memory locations of the message buffer. The logic device also generates an address for each of the transferred command and status words representing the address within the message buffer holding a particular command or status word. This command or status word address is stored into one of the memory locations of the pointer table. The logic device further stores characteristics of the message words and messages along with the message words into the memory device including whether a message is data or command/status, whether a message word has valid parity, whether all data and parity bits in a message word are validly Manchester encoded, and the relative time that the address of the first word in each message is stored into memory. This information is sufficient for host analysis software to diagnose and display bus traffic and aid in diagnostic testing of the AS1773 data bus.