Comparison of communication architectures for a fiber-positioning spectrograph

Abstract

The communication architecture required to provide a bidirectional communication between a central command node and a full set of fiber positioners feeding a spectrograph is studied. Six different architectures have been analyzed in terms of communication time and power consumption. These architectures are the result of the combination of three different communication protocols: transmission control protocol/internet protocol (TCP/IP) over ethernet, interintegrated circuit (I2C), and controller area network. The design of communication architecture must prioritize between communication time and power consumption. The fastest architecture is the hybrid TCP/IP over ethernet-I2C. This architecture requires the least time to provide a full set of coordinates to every fiber positioner less than 50 ms. The most power efficient solution is the I2C - I2C with demultiplexers. This architecture solves a bidirectional communication between a central node and a full set of fiber positioners requiring only an addition of 27 mW. © 2019 Society of Photo-Optical Instrumentation Engineers (SPIE).