1. SRB data transmission Vito Palladino CERN 2 June 2014

2. Reminder The total amount of SRB per station is 8 Each SRB provides readout of half a view (256 straws) The communication protocol is UDP and JUMBO frames are foreseen (9kB), without fragmentation Two possible read-out modes: ◦ Triggerless (TL) ◦ L0 trigger matching Straw is crucial for L1 trigger logic

3. Data Throughput in TL Mode The data throughput has been estimated, the following data are the inputs I used: ◦ average rate per straw: 60kHz (maximum luminosity) or a fraction of it ◦ Correction factor for extra hits: 1.3 ◦ Burst duration: 5s ◦ SPS super-cycle: 15s ◦ N bursts per day: 5760 ◦ Transmission type: UDP jumbo frames (9kB) ◦ The UDP packet length is limited at 9kB per packet in order to fit in one Ethernet frame (no fragmentation)

4. Data Throughput (DT) Full luminosity20% FL1% FL Average rate per Straw (kHz)60120.6 DT per SRB (Gb/s)1.290.260.012 Data per SRB per Burst (MB)8001608 DT per station (Gb/s)10.32.10.1 Data whole detector (TB/d)~148~30~1.5

5. Possible Solution for TL Mode Straw 4 Straw 3 Straw 2 Straw 1 SRB8 SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1 SRB8 SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1 SRB8 SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1 SRB8 SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1 Opt Switch 2x1Gb/s Merger Opt Switch 10(+10)Gb/s PC farm PC 10Gb/s 1Gb/s

6. Conclusions At full luminosity: ◦ We need:  Both Gb ports from the SRB to the switch (not yet implemented in the fw)  The second 10Gb/s link to the PC farm (not installed) ◦ The data transfer rate from the PC farm to the merger is NOT enough to sustain our rate (a L1 trigger selection is needed) even if we transmit data off spill The TL mode will be the first step in order to test the detector (connectivity, timing, alignment, etc.)

7. Ongoing Activities Infrastructure: ◦ Switches (network) and optical links (trigger and clock) will be installed by next week. Firmware and network test: ◦ A test board with Gb connectivity will be used to test the infrastructure and data transmission to the PC farm, the fw could be adapted to the SRB. PC farm: ◦ Jonas is working to modify the PC farm in order to receive the data in straw TL mode (1 SRB sends data to 1 PC). ◦ The L0 trigger matching do not requires any extra work.