In my last post, I discussed how the VeriLogger GUI can be configured to control different simulators. Today I’ll cover the executable programs used during a typical simulation run and how they communicate with each other.

It’s particularly important to note that these programs communicate via CORBA calls using network sockets, so any firewall software on your system needs to be configured to allow this communication. Please note that this “network communication” is all strictly local to the user’s computer: no internet activity is involved. Unfortunately, most windows-based firewalls do not, in their default configurations, differentiate between inter-process and inter-computer socket communication. Most firewalls will pop-up a warning when you build and run a simulation, and this is the the best time to allow the necessary socket access. However, there are some less commonly used firewalls that are not so friendly about notifying you when it begins blocking communications.

Syncad.exe, the BugHunter debugging GUI, is the program that the user typically interacts with. Syncad.exe launches simwrapd.exe when you first build a project by pressing the yellow “Build” button. Simwrapd.exe is a “simulation wrapper” that translates commands back and forth between the debugger GUI and the simulator, so that the debugger doesn’t need to know details of which simulator is being used. Simwrapd also theoretically allows remote simulations to be run transparently by the user, but this feature is not yet enabled in current versions of BugHunter.

Simwrapd, in turn, starts a simulator executable (vlogcmd.exe or simx.exe, for example). When
simx.exe (the VeriLogger Extreme command line simulator) is run, it then runs another exe called simxgen.exe. Simxgen is the “simulation generator” that compiles these user’s code to an simulation executable file called simxsim.exe. Simxsim.exe is then run to actually compute the results of the simulation.

All the above executables except simxsim.exe are located in the SynaptiCAD/bin directory. Unlike the other exe files, simxsim.exe is not shipped with the product, but is instead created based on the user’s source files, so it is generated into the project directory where the user’s project file (.hpj) is located.
Simxsim.exe is the simulation exe that gets run when you press one of the green “Run” buttons.

The socket communication channels when using VeriLogger Extreme are as follows:
syncad.exe <->simwrapd.exe
simwrapd.exe<->simxsim.exe
syncad.exe<->simxsim.exe

The socket communication channels when using the older vlogcmd simulation are as follow:
syncad.exe <->simwrapd.exe
simwrapd.exe<->vlogcmd.exe
syncad.exe<->vlogcmd.exe

The key difference, however, between simxsim.exe and vlogcmd.exe is that a new simxsim.exe is created with every compile and it is created in the project directory, whereas there’s only one vlogcmd.exe and it’s always located in SynaptiCAD/bin (because it’s an interpreted simulator, not a compiled one).