Abstract: A control module of a label printing apparatus includes memory configured to store item data and shelf label data indicative of an ID of an electronic shelf label (ESL) for the item, and at least one communication module configured to: receive, from an external device, an update request to make at least one change to the item data and communicate an ESL update request to the ESL to make the at least one change at the ESL. A processor of the control module is configured to: update the item data stored in the memory according to the update request; determine if the ESL has been updated in dependence on whether an acknowledgement is received from the ESL; and if the ESL has not been updated, control the communication module to output an alert signal to indicate that the ESL is out of sync with the label printing apparatus.