It can support EtherCAT and CAN bus to expand digital IO, analog AD and DA. When IO, AD and DA resources are insufficient, a coupler module (ECAT, CAN communication module) is required to be expanded with other expansion submodules. The submodules include digital input port IN, digital output port OUT, analog input port AD, and analog output port DA modules. A single coupler supports up to 16 expansion submodules.