is fiber optics communication module dedicated for ET-BUS of ET-DCS controller, allowing dispersion of I/O modules.
Its design allows bus operation (next I/O cassettes connected in series) or star topology (I/O cassettes connected to the cassette containing ET-CP which is center of "star" with many ET-FO modules). ET-FO modules can be installed on any location on a bus and add freely during operation, e.g. when controller expansion requires increased need for I/O signals quantity. Addition or exchange of ET-FO module does not require to stop or restart the controller.
ET-FO module has internal diagnostic system, which transfers current operation parameters and errors information to CPU ET-CP. Programmer can use this data e.g. for alarming or presenting status to a user.