INTRODUCTION

The correlation plot GUI functions as a device to manipulate, measure and correlate various physical quantities that govern LCLS beam quality. It may read, move and measure any process variables (PVs) that exist in an IOC (as long as the IOC is ON). PV format is usually, DEVICE:MICRO:UNIT#:DESCRIPTION. Correlation plot allows for 2 PVs to be controlled during a measurement of any number of other PVs and plots the result(s). It can drive a bunch length measurement, wire scanner, emittance application and the lclshome Profile Monitor individually.

RED BOX


Image:Corplot3.jpg

  • CONTROL PV NAME is the process variable name of the device that you would like to change during your scan. After typing the name in the box, press "ENTER". If the PV is real (correct name), you will see the "Current" and "Initial" values of the PV show up underneath the "Control PV Name". If they do not chnage from NaN (Not a Number) you have an incorrect name or the PV does not exist.
  • CTRL PV LOW/HIGH defines the range of the scan for the Control PV.
  • # CTRL PV VALS sets the number of data points to be taken within the range specified in "ctrl PV low/high".
  • SET CTRL PV BUTTON changes the value of the control PV to the Ctrl PV Low value.
  • RESET CTRL PV BUTTON will change the control PV back to its initial setting. Useful after an aborted scan.
  • INITIAL SETTLE TIME is the time in seconds the correlation plot GUI will wait before starting the scan. This is useful for allowing feedbacks to catch up if it so happens that your control PV is moving a magnet or a device that maybe used as an actuator for position or energy. BPM13 is a good and quick indication of energy feedback, once it is back to zero offset, the energy feedback has converged. For more precise confirmation, look at the feedback plots showing the setpoint, this will take a bit longer then looking up at the BPM. NOTE: BPM13 is an energy BPM and is only useful to look at when the energy is changed with the control PV.
  • SETTLE TIME is the time in seconds for the GUI to wait before making additional changes to the control PV, after the initial change. If big changes are being made or you need time inbetween data points, this will be useful.
  • FAST CONTROL PV is the second PV that can be changed during a measurement. Like the control PV name, this will also show a current and initial value for the PV, if it exists. Also has an associated ctrl PV low/high values, number of control vals, settle time and a set and reset ctrl PV buttons.
  • # SAMPLES gives you the ability to take a number of measurements at a given PV value before changing the PV for the next data point(s).
  • SAMPLE DELAY(s) is the time in seconds the GUI will wait before taking the next sample point after the previous sample.

BLUE BOX

  • START SCAN will start the scan of the PV(s), at this point the initial settle time will start to count down. If this is not the first scan a window will pop up asking you if you want to discard or save the data (to disk) previously generated. You may want to save the data, although pressing "LOGBOOK" should do this automaticly.
  • ABORT SCAN will quit all scans generated by the GUI (emittance, wire scans, etc...) as well as it's own scan. Be careful as the devices (PVs) that were being controlled will not return to their initial values and stay at the values they were aborted on. This may manifest itself as yellow magnets on the LCLS CUD, big beam trajectory oscillations as seen on the BPMs, railed feedbacks, etc... it all depends on what you are scanning.
  • GET DATA allows you to re-measure a single data point in a set... I THINK?????? not done
  • You may use LOAD CONFIG to load a previously saved setting of the GUI. For example, a particular emittance measurement may be unique in its quad scan ranges, or settle times, etc... and you may want to reproduce that measurement. Or if you forget certain settings for particular scans you can load a config, named by the date and time it was saved (unless you specify otherwise). This will also bring up the data obtained from the time it was saved, if data exists.
  • SAVE CONFIG will save the settings that are set in the GUI as you see them. Name is the date and time stamp unless otherwise named.
  • SHOW IMAGES check box does............
  • SAVE will save the data generated by the GUI to disk with teh date and time stamp as it's name. Directory path is /u1/lcls/matlab/data/2008/2008-month/2008-month-day/hhmmss.mat
  • SAVE AS does the same as "SAVE" but prompts you for a name (default is the date).
  • EXPORT will export the image of data as a matlab figure for manipulation, saving, etc...
  • LOAD will load a data set, specified by the you-ser in a prompt. The data will load into the GUI plotting areas. (May also load settings????)
  • SAVE IMAGES check box........................
  • LOGBOOK sends the generated plot(s) to the lcls-physics logbook and saves a copy to disk automatically. An image will be exported to the front of the desktop.

GREEN BOX

  • PROFILE MONITOR is a pull down menu of profile monitors used for LCLS. This can be driven by correlation plot to calculate beam statistics such as x and y size, rms and beam profile. Once started, you will get a figure plotting x (um), y(um), the beam X section and a small list of stats. A "# BG" box will appear for you to select the number of background images for the measurement.
  • WIRE SCANNER is a pull down menu of possible wire scanners to use for correlation plot measurements. Select the desired wire scanner in the correct region and select the plane you want to measure (x and y boxes show up to the right, once the WS is selected). Start the Correlation plot and it will call the Wire Scanner GUI and start the measurement. Look for the scrolling green bar.
  • EMITTANCE SCAN is a pull down menu of profile monitors that are typically used for emittance measurements. If one is selected, you are given a choice of multi screen or quad scans to measure the emittance. Once started, the Correlation Plot GUI will call the Emittance GUI for scanning in conjunction with the chosen control PV. If you would like to select a different screen in a different region that is not given in the pull down menu, you can abort the scan (from either GUI) and select the desired profile monitor in the emittance GUI, remember to select the correct sector the profile monitor lives in.
  • BUNCH LENGTH is a pull down menu of profile monitors capable of measuring longitudinal beam size (Z hat) using the TCAV application driven by the correlation plot. When started, the TCAV application will be called and a streaked beam (long in Z hat) will be incident on the profile monitor selected.
  • FORCE check box

YELLOW BOX

  • Plot Header will name the plots, M-files and configs generated by the gui. The name will also contain the date and time stamp corresponding to when they were saved.
  • The Formula box allows for the operator to enter a formula to fit the data generated, if the fit does not exist in the pull down menu mentioned in the orange section. "A" is the variable used for the control PV, "B", "C", "D", etc... corresponds to the DESCENDING list of X Axis PVs respectivley, neglecting the TIME variable (try both uppercase and lowercase, for some reason sometimes it seems to like one better than the other, but not consistantly).  Mathematical operators are defined by Matlab array notation meaning that for multiplication and division you need to put a period before the operator sign (i.e. .* or ./).  Addition and subtraction are as normal (+ or -).
  • Y Axis is a list of devices in the form of process variables (PVs) to be read by the GUI and written to the plot generated. You may select one or many PVs to be displayed as a function of the X Axis variable. The Y variable can be any PV from the "Read PV List" or any PV entered in the "Formula" box. "Ctrl + L-Click" will select PVs while maintaining previously selected PVs to be plotted on the same graph. A simple "L-Click" will only highlight one PV to be plotted. "Shft + L-Click" will highlight all PVs inbetween the first selected and the one you clicked last.
  • X Axis is a pull down menu of devices in the form of PVs to be read by the GUI and written to the plot generated. Typically the control PV, the X Axis variable can be anything from the "Read PV List" or any PV entered in the "Formula" box. Only one can be selected, unlike the Y Axis. TIME is also a variable.
  • U Axis is used for the 3D plots that can and may be generated. X, Y, U. PVs from the Read PV List and entered in the Formula box will also show up in the U Axis pull down menu.

ORANGE BOX

  • Read PV Listis a list of PVs to be read in by correlation plot. You may type (press enter when done) or drag PV names into this field.
  • Random Order when checked,
  • Pull Down Menu allows operators to choose the rate at which the read PVs are sampled if they are beam synchronous acquisition (BSA) PVs. The settle time vars have no effect when a rate is selected. Options are: 1, 10, 30 Hz.
  • Slider under the PV list shows the current value and name of the control PV during the scan. The left most position corresponds to the starting value (Ctrl PV Low).For each step the ctrl PV is moved, the slider will move to the right until it reaches the ending value (Ctrl PV High) which is the right most slider position.
  • Sample Slider allows you to view single sample points for a given value of the control PV. If the GUI measures n points (samples) before changing the control PV, (and AVG is not selected) you may view these points individually on the plot by sliding the slider.
  • Method Select is a slider with 7 options of methods to fit the data plotted.
  • 1 = Gaussian
  • 2 = Asymetric Gaussian
  • 3 = RMS
  • 5 = RMS Cut Peak 
  • 6 = RMS Cut Area
  • 7 = RMS Cut Floor
  • 3D Pull Down Menu exports an image with plotted data in one of three options: 3D, surface or scatter plots. Uses the U Axis.
  • Fit Pull Down Menu gives you a choice for fitting your data. Polynomial (choose the order), Gaussian, Sine and Parabola.
  • Show AVG when checked will avg the number of samples for one value of the control PV and plot a single data point with error bars. When left un-checked, the plot will show each sample individually for each value of the control PV.
  • Order is the order number used for the polynomial fit.



PLOTS

The top graph is utilized only when needed to show additional or supplemental information regarding the primary scan of the slow and/or fast control PVs. This is an example of a single OTR measurement








Henrik Loos's Talk

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