Slink Progress

1. Slink Progress James Leaver

2. Increased Data Rates • Using APVE to generate triggers (simulated TCS => backplane clock and trigger) • Can now drive FED at 100kHz • Can verify Slink transmissions ~10 times faster than with software triggers • But rate at which Slink data can be checked is limited to an absolute maximum of 4 x 106 words per second (CPU/memory speed) • Would take ~146 days to guarantee no more than one Slink error per week of CMS operation… James Leaver

3. FED Performance at 100kHz • ‘Simulate’ Zero Suppressed events: • Scope length 6 => 160Mbytes/s @ 100kHz • Cannot verify payload data, but can check that correct number of events are sent and events are of correct size • Repetitive (fixed period) triggers at 100kHz: • Sent ~8 x 109 triggers; received correct number of events with correct size • FED eventually ‘locked up’ due to extended Slink backpressure • With a hardware throttle, appears that FED will be able to operate successfully with 100kHz Repetitive triggers James Leaver

4. FED Performance at 100kHz • Random triggers at 100kHz: • FED randomly sends events of the wrong size • FED randomly ‘locks up’ – i.e. recognises further triggers, but refuses to output any events (should never happen) • Triggers are ‘missed’ • Problems even when Slink backpressure is ignored • Investigations still taking place… James Leaver

5. Future • Hardware throttle almost ready • Run FED with 100kHz Random triggers using hardware throttle – ‘ultimate’ stability test • Verify Slink transmissions at 100kHz using ‘bursts’ of triggers (reducing average data rate to < 4 x 106 words/second) • Check ‘header only’ mode James Leaver