Dealing with Different Versions of CATIA

Only one version of CATIA V5 can be registered with Windows at a given time. If you have R16, R17, and R18SP2 installed on your PC, only one of these is currently registered. You can find which one is registered by looking at the directory when you register. To automate a specific version of CATIA you first have t register that version with Windows. Here are the steps to un-register or re-register a CATIA V5 version:
 
1.        Reboot your pc
2.        Open a command prompt
3.        CD to the unload directory of the version of CATIA you want to un-register (i.e. “c\program files\dassault systemes\B15\intel_a\code\bin”)
4.        Run the command “cnext-unregserver”
5.        Open up the task manager and wait until the “cnext” process stops running (which may take a few minutes)
6.        CD to the unload directory of the version of CATIA you want to register (i.e. “c\program files\dassault systems\B16\intel_a\code\bin”)
7.        Run the command “cnext-regserver”
8.        In the task manager again, wait until the “cnext” process stops
9.        Open up VB and check that the correct version is registered
10.        Please note this only needs to be done between full releases and not service packs!