thank you for this assistance
Take a look at WINGUARD from the German company advancis.
Yes, I have come across Appvision and Vidsys here in the UK. I know of Appvision OEM that lets you build programs around the drivers they already have. I am told it is good to work with from a programmers point of view. Would be very inexpensive compared to CNL or Vidsys. Depends on how far you want to go managing the VMS from an outside application.
Miles, there are a company couple who claim to have 'found' PSIM - Vidsys, e.g, is another one.
The advantage of Prysm, from what I can tell is that it is very inexpensive, compared to CNL, Vidsys, Orsus, etc. which tend to be quite a lot of money.
IP Security Centre by CNL Software Home - CNL Software PSIM
They have worked worldwide with many industry's and include drivers for required VMS. Should have drivers for top 10 providers in each type of security system type. Lead to believe the founders of PSIM. Company director was one of the founders of Axis. Source: I previously worked for them.