  PKS 2155-304 is a well known GeV and TeV emitter and one of the brightest
blazars in the Fermi sky. We present the results of one year of data taking
with Fermi, producing the longest lightcurve on this object. Together with a
long duration X-ray monitoring program with RXTE, these data give a better
picture of the emission mechanisms for PKS 2155-304 on long time scales.
