The FEE Server Control Engine of the ALICE-TRD - Westfälische ...

FeeServer Core
creates an instance of
calls in a separate thread
5 The FEEServer Control Engine
CEStateMachine
calls its contructor
constructor main tasks:
− register DIM channels
− initialize the logging system
− sets the FSM state to STANDBY
CEStatemachine::loopFunction()
− contains an infinite loop
− task: sensor monitoring
Figure 5.2: Control flow during the initialisation of the control engine. The control flow is symbolized
by the solid lines. The dashed line is for illustration purpose only.
Second, the constructor initializes the logging system (for details see section 5.5). Third,
it initializes the FSM and sets the state of the FSM to STDBY.
When the control engine is initialized, the FEEServer core creates a separate thread
and calls the function int CEStateMachine::loopFunction(void). This function contains an
infinite loop. The function reads the DCS board temperature sensor and the voltage sensors
by calling float voltage_sensor::read_voltage(int) and float temp_sensor::read_temp(int)
(see section 5.2.4) and updates the corresponding DIM data channels in regular intervals.
If the MCMs are switched on later and the MCM temperature monitoring is activated
this function triggers the regular readout of the MCM temperature sensors, too. After the
initialization is finished the system waits for incoming commands from the ICL.
5.2.2 The Finite State Machine
Figure 5.3 shows the state diagram of the TRD frontend readout electronics. The finite
state machine (FSM) of the control engine implements all these states execpt the states
OFF and READY.
Description of the finite state machine states
In state OFF the supermodules have no power. The DCS boards are off and the FEEServer
with the control engine is not running. Therefore OFF cannot be reached by the control
engine itself.
When the DCS board is powered up, the FEEServer starts. The control engine is initialized
and the FSM has the state STDBY. In this state only the DCS boards have power. All
other parts of the chamber electronics including the MCMs and ORIs are still switched
off. Since the DCS board has power, the sensors on the DCS board are already active and
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