Design of the CMS-CASTOR sub detector readout system by reusing existing designs

CASTOR is a cylindrical calorimeter with a length of 1.5m and a diameter of 60cm located at 14.3 meters from the CMS interaction point and covering the range in pseudo-rapidity corresponding to 5.1 ~\textless~ \textbar~ eta~ \textbar ~ \textless ~ 6.6. The CASTOR project was approved in the middle of 2007. Given the limited resources and time, developing a readout system from scratch was excluded. Here the final implementations of the readout chain, the considerations for the different choices as well as the performance of the installed equipment are discussed.