The Blanco Telescope TCS upgrade

The Blanco 4-meter telescope has been in operation for over 30 years and is now subject to an extensive upgrade of its control system, both of the hardware and software aspects. The motivation for the upgrade, besides the normal replacement of obsolete components, is the preparation of the telescope for the installation of the DECAM instrument, which makes greater operational demands than can't be met by the current system. The architecture of the new system is in line with the designs proposed for modern telescopes like the Large Synoptic Survey Telescope (LSST), and its implementation utilizes similar technologies as proposed for that project. In this paper we present a detailed description of the upgraded system, including tape encoders, control algorithms, the use of trajectories to optimize motions, communications middleware, and its performance as a whole.