Busy Box and related: Difference between revisions

Revision as of 19:13, 19 February 2009

Overview

Traditionally the Fee in ALICE sub-detectors indicates when its buffers are full and cannot handle further triggers from the CTP. This is either done directly or through the FANIN module to the LTU with a busy signal.

Due to dense cabling, four of ALICE sub-detectors (TPC, PHOS, FMD and EMCal), utilize a BusyBox to keep track of free buffers in their Fec. The BusyBox asserts the busy signal to the LTU when one of these conditions is true: Buffers in Fec are full, upon receiving a trigger sequence from TTC or when the TTC sends a global reset to the Fee. The BusyBox is located in the DAQ counting rom.

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RCU Trigger Receiver Module

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 == Overview ==
-The Busy Box is located in the DAQ Counting Room. Its purpose is to halt the data taking when the system is saturated with event data. When the multievent buffers in the Front End Electronics run full, the Busy Box asserts a busy-signal to the Local Trigger Unit which halts the issuing of new triggers. The the busy-signal will be deasserted once there are available buffers.
+Traditionally the Fee in ALICE sub-detectors indicates when its buffers are full and cannot handle further triggers from the CTP. This is either done directly or through the FANIN module to the LTU with a busy signal.
-To calculate the number of used mulitevent buffers the Busy Box listens to the trigger system to see which events have been triggered, and then poll all the DRORCs to see which events have been transfered to DAQ.
+Due to dense cabling, four of ALICE sub-detectors (TPC, PHOS, FMD and EMCal), utilize a BusyBox to keep track of free buffers in their Fec. The BusyBox asserts the busy signal to the LTU when one of these conditions is true: Buffers in Fec are full, upon receiving a trigger sequence from TTC or when the TTC sends a global reset to the Fee. The BusyBox is located in the DAQ counting rom.
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