Abstract: A remote sensing system including a control module coupled to a remote device module via an optical fiber is disclosed. The device module includes circuitry for detecting changes in physical parameters and for transmitting data relating thereto back to the control module in serial form via the optical fiber. Power for the circuitry within the device module is obtained from a photodiode which receives light from the control module via the optical fiber and no power multiplication is utilized except which the remote module is transmitting serial data back to the control module. Data signals are also provided from which monitoring of the integrity of the device module and connections thereto can be obtained.