In this paper we analyze the properties of the design of PLO controller based on the modulus-optimum criterion for an important class of non-oscillating linear plants with dead time and present some important properties of the settings not published so far. The results are used to design a suitable correction of the settings, which ensures that a sufficient stability margin is preserved. After inclusion of these enhancements a robust design method is obtained, which provides good performance even for systems with long dead time and is easy to implement. (c) 2013 Elsevier Ltd. All rights reserved.