The VdAstrid device
Status:
This documentation applies to version 1.0.33.38 of the VdAstrid device.
Contents:
Overview:
CVdBeamCurrent
BeamCurrent.IMean:
Løbende middelværdi af beamstrømmen - altid 'valid'. Midlet over 1 minute, opdateres løbende. I tilfælde af beamtab >0.5 mA tømmes bufferen som bliver brugt til midlingen - data forbliver gyldige, midling vil være mere støjfyldt indtil midlings bufferen igen er fuld. Dette er lavet for at beamtab hurtigt bliver reflekteret i Middelværdien.
BeamCurrent.IFit:
Løbenden fittet beam strøm. Beregnet som:
IFit = IMean * ( 1 - (T/2)/tau),
hvor T er 1 minute, og tau levetiden beregnet over 1 minute.
Er sat til 0 - samt markeret som 'invalid' indtil levetiden er tilgængelig første gang.
Levetids dataene starter med at blive opsamlet 40 sek. Efter acceleration (venter på Beam stabilisere sig + undulator kører ind.) Derefter går der yderligere 45 sekunder før der er samlet data nok op til at levetidsberegningerne starter. Lige inden der leveres data sendes værdien 0 som valid men markeret med 'HISTORY_MARK_INVALID_DATA'. Bruges af CSPlot til at lave en 'pæn' start.
I tilfælde af pludselige beamtab over 0.5 mA nulstilles levetidsberegningerne. I perioden indtil levetidsberegingerne igen er gyldige returneres IMean - stadig med valid sat.
Det første data returneret efter et detekteret beamtab vil for alle beamcurrent data typer (også de eksisterende) være markeret med 'HISTORY_MARK'
ASTRID Multiplexer
Parameter | Address | Description/Use |
UEVIPast.ctrl | G64 crate 821 (diagnostic) parameter 2 control, (a0=2, a1=2) | Internal parameter. Split into parts by vdMultiplexer (in
vdASTRID.dll) bit 0-4: static Mux 1 value, Mux 1 scan stop value bit 8-12: static Mux 2 value bit 5-7 + 13-14: Mux 1 scan start value bit 15: Mux 1 scan (0: No scan, 1: Scan running) |
UEV1ast.ctrl | vdMultiplexer par 1 | Interpretation 804 Multiplexer |
UEV1ast.scan | vdMultiplexer par 0 | Interpretation 512 |
UEV1ast.start | vdMultiplexer par 2 | |
UEV1ast.stop | vdMultiplexer par 1 | Physically the same as .ctrl |
UEV2ast.ctrl | vdMultiplexer par 4 | Interpretation 804 Multiplexer |
UEVScanAst.TrigSpc | G64 crate 821 (diagnostic) bit 0-7 of parameter 2 control-data, (a0=2, a1=3) | Trigger spacing is (TrigSpc+1)*10ms Min = 1, Max = 254 |
UEVScanAst.TrigPls | G64 crate 821 (diagnostic) bit 8-15 of parameter 2 control-data, (a0=2, a1=3) | Specifies number Trigger Pulses before pickup change Min = 1, Max = 126 |
VdButtonPickupDevice
The VdButtonPickupDevice takes the four readings of four buttons and calculates a X and a Y position, together with standard deviations (if more than one reading are averaged).
The VdButtonPickupDevice is derived from CCalcDevice, and for address Definition the device uses AddTypeId number 9 (One-dim address) which uses a0 to determine the parameter number.
At present (030904) the device supports three button pickup (of four individual
buttons), and each button pickup has a given index added to parameter index.
Index offset:
UBX21ast: offset 0
UBX31ast: offset 10
UBX11ast: offset 20
parameter |
Suggested |
Parameter description |
Data Type |
Mode |
Interpretation |
Comment |
0 |
Xpos | R | ||||
1 |
Ypos | R | ||||
2 |
XposSig | R | ||||
3 |
YposSig | R | ||||
4 |
NoToMean | W | Word | |||
5 | Sum | R | The sum of the 4 input buttons. This is proportional to the beam current. | |||
6 |
SumSig | R |
Configuration:
None, since the parameter names are hardcoded in the device.
Hardware:
Finn Abildskov has made a BPM box, which has four individual demodulators, one for
each button. The four voltages are then proportional to the induced signals on
the four buttons. The individual buttons are labeled A, B, C, and D. A is the
upper left, B is upper right, C is the lower right, and D is the lower left SEEN
IN THE BEAM DIRECTION.
To first order the positions are given as:
X = (B+C-A-D)/Sum * scaleFactor
Y = (A+B-C-D)/Sum * scaleFactor
scaleFactor depends on distance of the buttons from the center, and is given by
the distance diveded by Sqrt(2). For the two button pickups we have today
(030904) the numbers are
UBX21: 22.27 mm
UBX31: 52 mm
Each button pickup has four individual buttons, of which the ConSys parameter
surnames must be named Ain, Bin, Cin, Din (hardcoded in the device).
Finn Abilskovs demodulator has four control bits to control it:
bit 0: input: (signal/zero): Changes the input to the demodulator between the
signal line (the button) and a zero.
bit 1: source: (beam/generator): Changes the input to the demodulator between
the beam (the button) and the generator input on the front of the demodulator
box (splitted out to the four channels)
bit 2: calibration: (off/on): With calibration on the signal from the four
buttons are first summed and then equally splitted to the four individual
demodulators.
bit 3: range (high/low): The low range gives a higher amplification, usefull for
low beam currents (below ~50 mA).
Last Modified 23 May 2023