Inspecting and/or testing of inline conveyed devices is performed in that a monitoring unit is applied to a device. The monitoring unit is removed in a removing area. Within the timespan the monitoring unit is applied to the device, the monitoring unit is operated in a standalone operating mode. During a timespan information about the device to which the monitoring unit is applied is collected in the monitoring unit. This timespan of collecting includes at least a part of the timespan during which the monitoring unit is operated in standalone mode.