This paper describes a design methodology for the estimation of bus performance of a tuplespace for factory automation. The need of a tuplespace is motivated by the characteristics of typical embedded architectures for factory automation. We describe the features of a bus for embedded applications and the problem of estimating its performance, and present a rapid prototyping design methodology developed for a qualitative and quantitative estimation. The methodology is based on a mix of different modeling languages such as Java, C++, SystemC and Network Simulator2 (NS2). Its application allows to estimate the expected performance of the bus under design in relation to the developed tuplespace.