Designing parallel programs for message-passing systems is not an easy task. Difficulties arise largely due to human limitations in identifying relationships between simultaneously executed program components, or processes, and between the data computed by these processes. This paper presents a parallel program visualization tool, Visputer, that provides the ability to graphically design and edit message-passing programs written in Occam2, configure parallel processes onto a multi-transputer network and visualize the execution of programs. The textual versions of programs and network configurations are automatically generated by Visputer based on program and network graphs, and then statically analysed for their performance and communication patterns. Animation of program execution is achieved by instrumenting the original program with event collecting code. The event collection method maintains program behaviour and imposes little performance impact on the original program.