The ATLAS tracking system will be replaced by an all-silicon detector for the HL-LHC upgrade around 2025. The innermost five layers of the detector system will be pixel detector layers which will be most challenging in terms of radiation hardness, data rate and readout speed. A serial power scheme will be used for to reduce the radiation length and power consumption in cables. To handle the expected data output of about 11 Tb/s, a high-speed transmission chain with many parallel lines running at 1.28 Gb/s will transmit data from the detector to an opto-electrical conversion system. This Optosystem features custom-designed radiation-hard electronics devoted to signal equalisation, aggregation (to 10.24 Gb/s) and optical-electrical conversion.
Operation of the optical system together with FELIX readout hardware, which is also used to trasmit DCS data, is currently being tested using RD53 prototype ASICs and will soon be included in the larger scale Demonstrator setups. In this talk we will present the current status of the system tests exercising these systems.