areaDetector Simulation driver

August 18, 2009

Mark Rivers

University of Chicago

 

Table of Contents

Introduction

simDetector is a driver for a simulated area detector. The simulation detector is useful as a model for writing real detector drivers. It is also very useful for testing plugins and channel access clients.

This driver inherits from ADDriver. It implements nearly all of the parameters in NDStdDriverParam_t (see asynNDArryDriver.h) and in ADStdDriverParam_t (see ADArrayDriver.h), with the exception of the file saving parameters, which it does not implement. It also implements a few parameters that are specific to the simulation detector. The simDetector class documentation describes this class in detail.

The writeInt32 and writeFloat64 methods override those in the base class. The driver takes action when new parameters are passed via those interfaces. For example, the ADAcquire parameter (on the asynInt32 interface) is used to turn acquisition (i.e. computing new images) on and off.

Simulation driver specific parameters

The simulation driver-specific parameters are the following:

Parameter Definitions in simDetector.cpp and EPICS Record Definitions in simDetector.template
Enum name asyn interface Access Description drvUser string EPICS record name EPICS record type
SimGainX asynFloat64 r/w Gain in the X direction SIM_GAINX $(P)$(R)GainX
$(P)$(R)GainX_RBV
ao
ai
SimGainY asynFloat64 r/w Gain in the Y direction SIM_GAINY $(P)$(R)GainY
$(P)$(R)GainY_RBV
ao
ai
SimGainRed asynFloat64 r/w Gain of the red channel SIM_GAIN_RED $(P)$(R)GainRed
$(P)$(R)GainRed_RBV
ao
ai
SimGainGreen asynFloat64 r/w Gain of the green channel SIM_GAIN_GREEN $(P)$(R)GainGreen
$(P)$(R)GainGreen_RBV
ao
ai
SimGainBlue asynFloat64 r/w Gain of the blue channel SIM_GAIN_BLUE $(P)$(R)GainBlue
$(P)$(R)GainBlue_RBV
ao
ai
SimResetImage asynInt32 r/w Set to 1 to reset image back to initial conditions RESET_IMAGE $(P)$(R)Reset
$(P)$(R)Reset_RBV
longout
longin

For monochrome images (NDColorMode=NDColorModeMono) the simulation driver initially sets the image[i, j] = i*SimGainX + j*SimGainY * ADGain * ADAcquireTime * 1000. Thus the image is a linear ramp in the X and Y directions, with the gains in each direction being detector-specific parameters. Each subsquent acquisition increments each pixel value by ADgain*ADAcquireTime*1000. Thus if ADGain=1 and ADAcquireTime=.001 second then the pixels are incremented by 1. If the array is an unsigned 8 or 16 bit integer then the pixels will overflow and wrap around to 0 after some period of time. This gives the appearance of bands that appear to move with time. The slope of the bands and their periodicity can be adjusted by changing the gains and acquire times.

For color images (NDColorMode=NDColorModeRGB1, RGB2 or RGB3) there are 3 images computed, one each for the red, green and blue channels. Each image is computed with the same algorithm as for the monochrome case, except each is multiplied by its appropriate gain factor (SimGainRed, SimGainGreen, SimGainBlue). Thus if each of these color gains is 1.0 the color image will be identical to the monochrome image, but if the color gains are different from each other then image will have color bands.

Unsupported standard driver parameters

Configuration

The simDetector driver is created with the simDetectorConfig command, either from C/C++ or from the EPICS IOC shell.

int simDetectorConfig(const char *portName, 
                      int maxSizeX, int maxSizeY, int dataType,
                      int maxBuffers, size_t maxMemory, 
                      int priority, int stackSize)
  

The simDetector-specific fields in this command are:

For details on the meaning of the other parameters to this function refer to the detailed documentation on the simDetectorConfig function in the simDetector.cpp documentation and in the documentation for the constructor for the simDetector class.

There an example IOC boot directory and startup script (iocBoot/iocSimDetector/st.cmd) provided with areaDetector.

MEDM screens

The following is the MEDM screen ADBase.adl connected to a simulation detector.

ADBase.adl

ADBase_sim.png

The following is the MEDM screen that provides access to the specific parameters for the simulation detector.

simDetector.adl

simDetector.png

Image viewers

The following is an IDL epics_ad_display screen using image_display to display the simulation detector images.

epics_ad_display.pro

simDetector_image_display.png

The following is an ImageJ plugin EPICS_AD_Viewer screen displaying color simulation detector images.

ImageJ plugin EPICS_AD_Viewer

simDetector_ImageJ_display.png