主权项 |
1. A portable interface device for controlling a machine at at least two control locations,
wherein the portable interface device is arranged to control the machine at either of the at least two control locations, wherein the portable interface device is arranged to detect whether the portable interface device is located at the at least two control locations, wherein the portable interface device is arranged to identify at which of the at least two control locations the portable interface device is located, wherein the portable interface device is arranged to enable the machine to be controlled via the portable interface device for a limited period of time after a positive detection, wherein the limited period of time depends on which of the at least two control locations was identified, wherein the portable interface device is arranged to verify that the portable interface device is located at the either of the at least two control locations, wherein the portable interface device is arranged, in response to a positive verification, to enable a user to control the machine via the portable interface device, thereby providing a facility for the user to control the machine via the portable interface device, and wherein the portable interface device is arranged, in response to a negative verification, to disable the facility for the user to control the machine, but to enable information about the machine to be displayed. |