@ Cubit, thanks. I did look at the Adams convertors but I was unsure if they were being used in the security field as all the brochures were about industrial automation etc. That might be something I can look into so long as the whole setup does not become cost prohibitive.
@Wistle, thanks for the idea, but the problem is at the moment the client only wants a few IP cameras to provide surveillance on the highest priority assets. And these will only be installed close to two of the IR beam receivers.
@Alarm Protection, thanks, contacted them already, hope to hear what solutions they can suggest.