Some cameras and video servers have the ability to accept alarm inputs. These are inputs from standard sensor devices such as, Passive Infra-red (PIR) detectors, door contacts, active beams etc. or relay outputs from intruder alarm panels, or access control panels.
Alarm input circuits can come in a number of forms. Most commonly they are self powered, so will operate with a passive switch style circuit. However, in some cases, they expect to be provided with power (normally 12V) as the signal of open or closed. In a few cases manufactures only supply TTL (very low voltage) level inputs. In that case, they can only be safely used with normal alarm sensors in conjunction with some additional isolation circuitry. In this case, it is best to contact the manufacturer for advice.
