Instrument software simulators are becoming essential both for supporting the instrument design and for planning the
future operations. In this paper we present the Software Simulator developed for the METIS coronagraph, an instrument
of the Solar Orbiter ESA mission. We describe its architecture and the modules it is composed of, and how they
interchange data to simulate the whole acquisition chain from the photons entering the front window to the stream of
telemetry? data received and analysed on ground.
Each software module simulates an instrument subsystem by combining theoretical models and measured subsystem
properties. A web-based application handles the remote user interfaces of the Institutions of the METIS Consortium,
allowing users from various sites to overview and interact with the data flow, making possible for instance input and
output at intermediate nodes.
Description of the modes of use of the simulator, both present and future, are given with examples of results. These
include not only design-aid tasks, as the evaluation and the tuning of the image compression algorithms, but also those
tasks aimed to plan the in-flight observing sequences, based on the capability of the simulator of performing end to end
simulations of science cases.