4.12 SIMULATION

The purpose of simulation is to allow the use or testing of software which depends on other processes which are not yet available. Example: a developer wants to test a WS process which interacts with a process on a LCU. In case no LCU is available or the LCU process is not yet existing, he can use simulation to simulate the existence of the LCU process.

Simulation can be done on different levels:

· WS level:

· use the cmdManager to simulate replies from non existing processes. In this way other WS or LCU processes or complete LCUs can be simulated. This simulation is relatively simple to set up. Disadvantages is that the simulation is static, the replies are static and no realistic timing is possible. However, it is possible to include, in the simulated replies, references to database attributes. The actual attribute value will be plugged, at run time in the reply. In this way, it is possible to dynamically change in the database, using auxiliary processes, or the scan system, or with the calculation engine the attribute value, and thus the content of the simulated reply.

· LCU level:

· simulate complete LCU: set the lccServer in simulation mode. This will automatically disable all accesses to hardware connected to LCC (acro and aio boards). Other type of hardware controlled by software devices has to be simulated by the device control software. Motors has to be set in simulation mode. This allows a more realistic simulation, but requires availability of the LCU and more effort for software development.

· set individual LCU processes in simulation mode to simulate a part of an LCU. In this case the process has to completely take care of the simulation of hardware it is using.

· use VxSim (product from Wind River System) to emulate the VxWorks environment of your LCU on the workstation.