The On-Board Data-Handling (OBDH) subsystem represents the core of satellite system from the point of view of managing the communication between the satellite and the ground station. During the development of the OBDH subsystem, the protocol operation of the OBDH subsystem bus must be monitored and tested carefully before the real environment applications. For this purpose, in this thesis, a Protocol Analyzer is designed and implemented to assess the OBDH bus performance and to isolate and locate bus faults and errors. The OBDH bus is based on a recently suggested virtual implementation of MIL-STD-1553B standard. The Virtual MIL-STD-1553B (V1553B) is implemented on an asynchronous RS-485 physical layer. Also, modifications were suggested to improve fault tolerance and error trapping capability of the bus. The Protocol Analyzer is capable for tracing, storing, and analyzing the V1553B messages. Also, the analyzer displays the analyzed protocol messages on the screen and records them in a log file. Protocol generating system has been implemented to generate and transmit the modified V1553B messages. This generating system is used to test the performance of the Protocol Analyzer. The Protocol Analyzer and the protocol generating system are implemented using two personal computers. This work represents a step forward towards implementing a complete satellite On-Board Data Handling subsystem.