The SDO Gateway Add-on implements a SDO gateway function, which makes possible the SDO transfer between two or more CANopen networks. To use this feature, the gateway device must feature at least two CANopen instances. A so-called CANopen SDO server receives the SDO messages of the client residing on the one side, and handles the transfer to the targeted SDO server on the subordinated CANopen network. The SDO response messages are handled vice versa. This implementation of the SDO gateway does not support dynamic SDO channels.