From logical to physical architecture The following slides uses the example of RT-knobs to study the transition of logical to physical architecture.

Real time knobs some reflections on rt knobs Real time knobs fit in perfectly in an rt control architecture. If an rt-knob is controlled by an rt measurment, we have an rt-feedback system. Here they are used to study possible physical architectures. How are they defined and how do they work What do they have in common with other RT control such as feedback. What is needed to control them What are the physical architectural issues

Real time knobs Definition of a knob (real time or software) a parameter that is linked to a set of equipment with some precisely defined knob-functions to modify the setting of the equipment: EquipValue n = Knob.Function n (Knob.value) Examples I QF (t) = IRef QF (t) + Delta IQF * QhKnob.value I QF (t) = IRef QF (t) + IRef QF (t) * delta IQF * QhKnob.value The Knob Function may include other reference parameters as well: I QF (t) = IRef QF (t) + EnergyRef(t) * Delta IQF * QhKnob.value To use a knob with a Knob Function that include reference values on a device while the reference functions are changing (I.e. during a ramp) requires that the knob converters know the reference functions and that they are synchronised with the equipment.

Knob D Knob CKnob B RT-knobs: Logical Connection diagram Knob A Device-1Device-2Device-3 RTdev-1RTdev-2RTdev-3 Function A-1 Device-4Device-5 Device-6 Function A-2Function A-3Function B-2Function B-3Function B-4Function C-1Function C-5Function D-6 Function D-99 Device-99 Sum-1Sum-2Sum-3Sum-4Sum-5

Real time knobs Observations: A single knob can be linked to more than one equipment. More than on knob can be linked to the same equipment. The knob function can be expressed as a function of the knob variable, and any of the equipment reference variable (provided that they can be made known to the knob- converter) The knob functions do not have a rigid definition, their definition can be modified when needed. Real time knobs are made from knobs by linking the knob value to a real-time output device (operator console, q- measurement feedback)

Knob D Knob CKnob B RT-knobs: implementation 1, Central knob processing Knob A Device-1Device-2Device-3 RTdev-1RTdev-2RTdev-3 Function A-1 Device-4Device-5 Device-6 Function A-2Function A-3Function B-2Function B-3Function B-4Function C-1Function C-5Function D-6 Function D-99 Device-99 Sum-1Sum-2Sum-3Sum-4Sum-5

RT-knobs: implementation 1, Central knob processing Description: –RT output devices send RTknob values to a central RTknob process –The RTknob process sends one correction value message for every knob update to the involved devices. Multiple knob updates in the same slot are combined The RTknob process may also broadcast correction values even if nothing changed  Since the summing is done centrally, the knob processing is best performed centrally. RT output devices have to communicate with the central RTknob process.  The central RTknob process may take into account dependencies between knobs values (cross terms: EquipValue = function(knob.A, knob.B) )  Bandwidth usage: –Nknobs * knob-update-frequency + –Ndevices * knob-update-frequency

Knob D Knob CKnob B RT-knobs: implementation 2 summing by the devices Knob A Device-1Device-2Device-3 RTdev-1RTdev-2RTdev-3 Function A-1 Device-4Device-5 Device-6 Function A-2Function A-3Function B-2Function B-3Function B-4Function C-1Function C-5Function D-6 Function D-99 Device-99 Sum-1Sum-2Sum-3Sum-4Sum-5

RT-knobs: implementation 2 summing by the devices Description: –RT output devices send RTknob values to a dedicated RTknob process –The RTknob process sends one correction value message for every knob update to the involved devices. Multiple knob updates in the same slot are combined The RTknob process may also broadcast correction values even if nothing changed –The summing of the knob corrections is done on the device  Since the summing is on the device, the knob processing may be distributed.  RT output devices may include the RTknob process  Dependencies between knobs values (cross terms) can only be managed if the knobs are handled by the same RTknob process.  Bandwidth usage:  Number of knobs * knob-update-frequency +   (Ndevices/knob * knob-update-frequency) (summed over all the knobs)

Knob D Knob CKnob B RT-knobs: implementation 3 knob functions in the devices Knob A Device-1Device-2Device-3 RTdev-1RTdev-2RTdev-3 Function A-1 Device-4Device-5 Device-6 Function A-2Function A-3Function B-2Function B-3Function B-4Function C-1Function C-5 Function A-6Function A-99 Device-99 Sum-1Sum-2Sum-3Sum-4Sum-5

RT-knobs: implementation 3 knob functions in the devices Description: –RT output devices send RTknob values to all subscribed devices The device executes the Knob calculation locally The summing of the knob corrections is done locally Dependencies between knobs values (cross terms) can be managed locally on the device.  RTknobs can be used more easily during ramps.  Bandwidth usage is the lowest –Number of knobs * knob-update-frequency  Processing on the device is highest (however, if only simple linear knob functions are used this should be ok)  RTKnob values can be broadcast (no point to point communication). It could use the slow-timing services or any other means.  The ramp itself could be implemented as an RTknob ( although in reality one will not have all the freedom as one may think, e.g. variable ramp speeds, due to dynamic effects ).

Gateway controller Knob D Knob CKnob B RT-knobs: implementation 4 knob functions distributed as processes of local fieldbus masters Knob A Device-1Device-2Device-3 RTdev-1RTdev-2RTdev-3 Function A-1 Device-101Device-102 Device-6 Function A-2Function A-3Function B-2Function B-3Function B-101Function C-1Function C-102 Function A-6Function A-99 Device-99 Sum-1Sum-2Sum-3Sum-101Sum-102 Ranp Function R-1 Ranp Function R-2 Ranp Function R-3 Ranp Function R-101 Ranp Function R-102 Fieldbus timing

RT-knobs: implementation 4 knob functions distributed as processes of local fieldbus masters –A combination of implementation 1 and 3. –Processing is done distributed in processors that have access to the local equipment bus.  The high bandwidth communication is isolated on the local equipment bus.  This system is more appropriate for local feedback loops.  The function generation could be implemented in software modules running on the local processors.  More flexibility on the long term.  Simpler electronics.  Function generation (for test and debugging) can be done locally from the local equipment bus control processor.