Load handling device with assigned code

A load handling device (31, Fig 3) for lifting and moving containers (9, Fig 4) stacked in stacks in a grid storage structure (1) comprising a track system (Fig 2) on which load handling devices 31 travel. Devices 31 comprise a transmitter 112 configured to transmit data and a receiver 114 configured to receive the data from transmitter 112. Each load handling device (31) is assigned a code (Fig 9A), such that transmitter 112 transmits the code along with data and receiver 114 discards received data not comprising the code. Also shown is gripping device 100, body and/or gripping device controller 122 and synchronised clocks 118. Transmitter 112, coupled to gripping device 100, may be a light transmitter (LED, IR, optical wireless communication OWC, visible light communication VLC, Li-Fi etc.) and receiver 114 is a light or photo detector. Codes assigned to devices (31) are vector codes consisting of chips and may be generated by code division multiple access (CDMA). An associated system and method of controlling such a system, as well as method of controlling devices (31) are also disclosed.