Abstract: A portable alarm device which includes a casing containing one or more of the following; means for detecting that the device has been moved, means for detecting a person in the vicinity of the device and means for detecting changes in ambient light level. The device further includes a scrolling system which makes each of said means available in turn for receiving commands that are inputted manually. The device has a code accepting unit which receives an inputted code to bring the device to a condition in which a selected one of said means can be activated. The device is deactivated by insertion of said code for a second time. By providing the device with a sound generator and a sound receiver it is possible to interconnect the devices so that activating or deactivating one is used to activate or deactivate a series. Likewise the establishment of an alarm condition at one device can be used to trigger alarm conditions at other devices.