The main function of the link is to provide simple, yet efficient standard interface for every detector in the ALICE experiment. At both interfaces of the link, the interface clock is supplied by the user. It allows the user to use the appropriate clock frequency for the readout. The front-end interface consists of a half-duplex, 32-bit data bus and a few control signals. During the acquisition phase, the interface behaves as a simple synchronous FIFO interface. The architecture of the link is

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... est described as data push architecture, where the transfer, including speed and rate, is controlled by the source. To guarantee the lossless transmission, the DDL uses full duplex flow-control mechanism. The ALICE Detector Data Link (DDL) is a high-speed optical link designed to interface the readout electronics of ALICE sub-detectors to the DAQ computers. The Source Interface Unit (SIU) of the DDL will operate in radiation environment. Tests showed that configuration loss of the Altera APEX II FPGA device used earlier on the DDL SIU card is only marginally acceptable. We developed a new version of the SIU card using Actel ProASIC+ device based on flash memory technology. The new SIU card has been extensively tested using neutron and proton irradiation. In this paper we present the SIU card and describe the results of irradiation measurements. At the level of the physical layer, we are using a bidirectional, high-speed optical link. Using 2.1 Gb/s serial speed, the peak data rate can exceed 200 MB/s. The backward channel allows detector control and/or configuration.