||Remote access of a Programmable Logical Control (PLC) is the prerequisite for an effective maintenance. We present an architecture for the development of tools supporting the installation, configuration, maintenance, supervision, and diagnosis of remote PLCs via the Internet. The developed architecture, called Virtual PLC, consists of a set of extensible components describing a real PLC. The Virtual PLC uses Java Technology to be platform independent. The Virtual PLC enables developers to rapidly implement tools for remote diagnosis, supervision and maintenance of a real PLC.