ADDexela 

AreaDetector Dexela driver

author:: Mark Rivers, University of Chicago

Introduction 

This is an areaDetector driver for the flat-panel CMOS detectors from Perkin Elmer.

The driver is based upon the Dexela library provided by Perkin Elmer. It only runs on Microsoft Windows computers. It supports both 32-bit and 64-bit versions of Windows.

This driver has been tested with the following detectors

Dexela 1512 with CameraLink frame grabber

This driver inherits from ADDriver. It implements many of the parameters in asynNDArrayDriver.h and in ADArrayDriver.h. It also implements a number of parameters that are specific to the Dexela detectors. The Dexela class documentation describes this class in detail.

Implementation of standard driver parameters 

The following table describes how the Dexela driver implements some of the standard driver parameters.

Implementation of Parameters in asynNDArrayDriver.h and ADDriver.h, and EPICS Record Definitions in ADBase.template and NDFile.template
Parameter index variable	EPICS record name	Description
ADNumImages	$(P)$(R)NumImages	Controls the number of images to acquire when ADImageMode is Multiple
ADAcquireTime	$(P)$(R)AcquireTime, $(P)$(R)AcquireTime_RBV	When using Internal Triggers, this parameter controls the period between trigger pulses which will also be equal to the exposure time.
ADTriggerMode	$(P)$(R)TriggerMode, $(P)$(R)TriggerMode_RBV	Sets the trigger mode for the detector. Options are: Int. Free Run Internal trigger, frame rate limited by ADAcquireTime and readout time; ADAcquirePeriod is ignorred. Int. Fixed Rate Internal trigger, frame rate controlled by ADAcquirePeriod, which must be greater than both the ADAcquireTime and the readout time. Int. Software Software trigger per frame. Ext. Edge Multi One external negative edge trigger starts a sequence of multiple frames; the frame rate is determined by ADAcquirePeriod, which must be greater than ACAcquireTime plus the readout time. Ext. Edge Single One external negative edge trigger for a each single frame. Ext. Bulb External bulb trigger; high to expose, low to read out.

Dexela specific parameters 

The Dexela driver implements the following parameters in addition to those in asynNDArrayDriver.h and ADDriver.h.

Parameter Definitions in Dexela.h and EPICS Record Definitions in Dexela.template
Description	EPICS record name	EPICS record type
The detector binning mode. The standard BinX and BinY records are not used because the Dexela detectors only support (at most) binning values of 1, 2 and 4 independently for X and Y. Specific detectors may restrict the choices further. For example the Dexela 1512 only supports 1x1, 2x2, and 4x4 binning. i.e. not 1x2, 2x4, etc. The menu choices for this record are constructed by the driver at initialization based on the actual capabilities of the detector in use.	$(P)$(R)DEXBinningMode, $(P)$(R)DEXBinningMode_RBV	mbbo, mbbi
The detector full-well mode. The choices are “Low noise” and “High range”.	$(P)$(R)DEXFullWellMode, $(P)$(R)DEXFullWellMode_RBV	mbbo, mbbi
The detector readout mode. The choices are “Continuous” and “Idle”. “Idle” disables continuous detector scrubbing, which allows prompt response to software or hardware triggers, at the expense of potentially larger dark current in the first few frames.	$(P)$(R)DEXReadoutMode, $(P)$(R)DEXReadoutMode_RBV	mbbo, mbbi
Trigger record for soft trigger mode	$(P)$(R)DEXSoftwareTrigger	bo
Corrections directory
Directory where offset, gain and defect map corrections files are stored	$(P)$(R)DEXCorrectionsDir	waveform
Offset corrections (also called dark current corrections)
Number of frames to collect and average when collecting offset frames	$(P)$(R)DEXNumOffsetFrames	longout
Current offset frame being collected when collecting offset frames	$(P)$(R)DEXCurrentOffsetFrame	longin
Acquire offset frames	$(P)$(R)DEXAcquireOffset	busy
Set whether offset image is to be used. Choices are “Disable” (0) and “Enable” (1).	$(P)$(R)DEXUseOffset	mbbo
Report whether offset image has been collected and is available for use. Choices are “Not available” (0) and “Available” (1).	$(P)$(R)DEXOffsetAvailable	mbbi
The name of the offset file to save or load. The CorrectionsDirectory will be used for the path.	$(P)$(R)DEXOffsetFile	waveform
Load offset corrections from a file for use	$(P)$(R)DEXLoadOffsetFile	longout
Save offset corrections to a file	$(P)$(R)DEXSaveOffsetFile	longout
An offset that is added to the image when the offset correction is performed. CorrectedImage = RawImage - OffsetImage + OffsetConstant. This constant should be used to prevent the CorrectedImage from having any negative pixel values, which would otherwise be clipped to 0.	$(P)$(R)DEXOffsetContant, $(P)$(R)DEXOffsetContant_RBV	longout , longin
Gain corrections (also called flat field corrections)
Number of frames to collect and average when collecting gain frames	$(P)$(R)DEXNumGainFrames	longout
Current gain frame being collected when collecting gain frames	$(P)$(R)DEXCurrentGainFrame	longin
Acquire gain frames	$(P)$(R)DEXAcquireGain	busy
Set whether gain image is to be used. Choices are “Disable” (0) and “Enable” (1).	$(P)$(R)DEXUseGain	mbbo
Report whether offset image has been collected and is available for use. Choices are “Not available” (0) and “Available” (1).	$(P)$(R)DEXGainAvailable	mbbi
Load gain corrections from a file for use	$(P)$(R)DEXLoadGainFile	longout
Save gain corrections to a file	$(P)$(R)DEXSaveGainFile	longout
Defect map corrections (also called bad pixel corrections)
Set whether defect map correction is to be used	$(P)$(R)DEXUseDefectMap	mbbo
Report whether defect map is available for use	$(P)$(R)DEXdefectMapAvailable	mbbi
File name for defect map file	$(P)$(R)DEXDefectMapFile	waveform
Load defect map from a file for use	$(P)$(R)DEXLoadDefectMapFile	longout

Unsupported standard driver parameters 

The Dexela driver does not support the following standard driver parameters because they are not supported in the Dexels library:

Type/Color (NDDataType, NDColorMode)
No Hardware shutter control

Configuration 

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

int DexelaConfig(const char *portName, int detIndex,
                      int maxBuffers, size_t maxMemory,
                      int priority, int stackSize )

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

Example st.cmd startup file 

There is an example IOC boot directory and startup script Example st.cmd Startup File provided with areaDetector.

MEDM screens 

The following show the MEDM screens that are used to control the Dexela detector. Note that the general purpose screen ADBase.adl can be used, but it exposes many controls that are not applicable to the Dexela, and lacks some fields that are important for the Dexela driver.

Dexela.adl is the main screen used to control the Dexela driver.

Dexela.adl 

Performance measurements 

The following measurements were done to demonstrate the performance that can be obtained with the areaDetector Dexela driver.

Dexela 1512 detector with the CameraLink PCI/E frame grabber
- Can stream data continuously to local disk at maximum unbinned (1536x1944) frame rate of 26 frames/s (149 MB/s) and 2x2 binned (773x972) at 70 frames/s (100 MB/s). These tests were done on a Windows 7 64-bit machine with 2 disk drives (SAS, 15K RPM, RAID 0).

Restrictions 

The following are some current restrictions of the Dexela driver:

Does not currently support saving images to disk with the Dexela library except for corrections files.
Single image mode is not working.
There is a long delay (>1 second) after setting Acquire=1 before collection actually starts.
Gain correction is not tested because I don’t have a way to collect flat field images.
Defect map correction is not tested because I don’t have a defect map file.