author:Mark Rivers (University of Chicago), Phillip Sorensen (Cornell University)


This is an EPICS areaDetector driver for CMOS detectors from Andor Technology. It has been tested on the Andor Neo sCMOS camera with 3-tap Camera Link interface, but should work with other cameras (e.g. Zyla) as well. The driver is supported on 32-bit and 64- bit Linux and 32-bit and 64-bit Windows. The driver is called “Andor3” because it is built with Version 3 of the Andor Software Development Kit (SDK). This version of the SDK is required to work with the Andor sCMOS cameras, and currently does not work with the Andor CCD cameras.

The driver provides access to essentially all of the features of the Andor sCMOS cameras:

  • Fixed number of frames or continuous acquisition.
  • Multiple accumulations per frame.
  • Readout frequency
  • Readout mode (11-bit low noise, 11-bit high-well, 16 bit combination).
  • Support for all of the Andor trigger modes
  • Binning and Area Of Interest (AOI) readout
  • Set and monitor the camera temperature
  • Set the camera fan speed.

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 Andor detectors. The andor3 class documentation describes this class in detail.

This document does not attempt to explain the meaning of the Andor-specific parameters. The Andor Software Development Kit documentation provides this detailed information. Andor does not allow me to redistribute the SDK documentation as part of areaDetector. It must be obtained from Andor’s Web site.

The Andor3 SDK is very well designed. Camera parameters (e.g. exposure time, binning) are called “features”. Features can be integer, float, bool, string, or enum. Each feature can be queried to determine if it is implemented on the current detector. In addition:

  • For integer and float features:
    • What is the valid range of values for the current camera under the current conditions?
  • For enum features
    • How many enum choices are there?
    • For each enum choice:
      • What is the string associated with that enum choice?
      • Is that choice implemented for the current camera?
      • If it is implemented, is it valid under the current conditions?
  • Ability to register a user-defined C callback function that will be called whenever a feature value changes. These changes can be the indirect result of changing another feature. For example, changing the binning might force the exposure time to change, etc.

The areaDetector driver uses these features. All of the enum menus are built dynamically at iocInit, they are not preset in the template file. This ensures that the enum choices match the actual capabilities of the current camera. Whenever an integer or float parameter is changed it is checked to ensure it is within the current valid bounds for that feature. The feature callback is used to ensure that the current EPICS readback value of that parameter matches the actual camera value, without requiring the driver to poll.

areaDetector includes the header and library files required to build the andor3 driver on any Linux or Windows computer. However, it does not include the shareable libraries, DLLs or drivers to actually run a detector. Those must be obtained from Andor, either by purchasing their SDK or their Solis application software. On Windows the path to the directory containing the Andor DLLs from the SDK or Solis must be added to the PATH environment variable when running the areaDetector IOC. On Linux the path to the directory containing the Andor shareable libraries from the SDK must be added to the LD_LIBRARY_PATH environment variable when running the areaDetector IOC.

Note: Linux drivers and Bitflow based camera may require the removal of files /usr/local/lib/libatusb*. These files sometime interfere with Bitflow based cameras on Linux (per Andor).

Implementation of standard driver parameters

The following table describes how the Andor 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
ADTriggerMode $(P)$(R)TriggerMode, $(P)$(R)TriggerMode_RBV Sets the trigger mode for the detector. Options for the Neo are:
External Start
External Exposure
ADImageMode $(P)$(R)ImageMode, $(P)$(R)ImageMode_RBV Sets the image mode for the detector. Options are:
Fixed counts collects NumImages images, continuous acquires continuously until acquisition is stopped.
ADNumExposures $(P)$(R)NumExposures, $(P)$(R)NumExposures_RBV Sets the number of accumulations per image. This is performed in Andor’s driver, not on the chip.
ADNumImages $(P)$(R)NumImages, $(P)$(R)NumImages_RBV Sets the number of images to take when ImageMode=Fixed.
ADAcquirePeriod $(P)$(R)AcquirePeriod, $(P)$(R)AcquirePeriod_RBV Sets the FrameRate (=1./AcquirePeriod). The FrameRate can also be set directly.
The minimum AcquirePeriod (maximum FrameRate) depends on a number of other parameters, including the A3Binning, SizeX, SizeY, ReadoutRate, A3ShutterMode, PixelEncoding, and Overlap.
NDDataType $(P)$(R)DataType, $(P)$(R)DataType_RBV The data type for the image data. Allowed values are:
The DataType is selected automatically, based upon the PixelEncoding record. The data type will be UInt32 if PixelEncoding is Mono32, and UInt16 for all other values of PixelEncoding. PixelEncoding=Mono32 can be used when A3Binning > 1x1, or when multiple accumulations (NumExposures > 1) could cause 16-bit overflow.
ADTemperature $(P)$(R)Temperature, $(P)$(R)Temperature_RBV Sets the setpoint temperature of the camera.
ADTemperatureActual $(P)$(R)TemperatureActual Reads the actual temperature of the camera.

Andor specific parameters

Parameter Definitions in andor3.cpp and EPICS Record Definitions in andor3.template
Parameter index variable asyn interface Access Description drvInfo string EPICS record name EPICS record type
Version information
Andor3SerialNumber asynOctet R/O Camera serial number A3_SERIAL_NUMBER SerialNumber stringin
Andor3FirmwareVersion asynOctet R/O Camera firmware version A3_FIRMWARE_VERSION FirmwareVersion stringin
Andor3SoftwareVersion asynOctet R/O SDK software version A3_SOFTWARE_VERSION SoftwareVersion stringin
Andor3ControllerID asynOctet R/O Camera controller ID A3_CONTROLLER_ID ControllerID stringin
Cooling control and status
Andor3SensorCooling asynInt32 R/W Turn the sensor cooler on and off A3_SENSOR_COOLING SensorCooling, SensorCooling_RBV bo, bi
Andor3TempStatus asynInt32 R/O Temperature status. Values and strings on the Neo are:
0 = Cooler Off
1 = Stabilized
2 = Cooling
3 = Drift
4 = Not Stabilized
5 = Fault
A3_TEMP_STATUS TempStatus_RBV mbbi
Andor3TempControl asynInt32 R/W Temperature setpoint value in degrees C. On the cooled cameras (e.g. Neo) the temperature is set to discrete values, rather than continuously with the Temperature record, because the firmware does pixel corrections for specific temperatures. Choices on the Neo are:
0 = -15
1 = -20
2 = -25
3 = -30
4 = -35
5 = -40
A3_TEMP_CONTROL TempControl, TempControl_RBV mbbo, mbbi
Andor3FanSpeed asynInt32 R/W Fan speed. Choices on the Neo are:
0 = Off
1 = Low
2 = On
A3_FAN_SPEED FanSpeed, FanSpeed_RBV mbbo, mbbi
Readout control and status
Andor3ShutterMode asynInt32 R/W Selects the shutter mode. Choices for the Neo are:
0 = Rolling
1 = Global
Rolling shutter mode interleaves exposure and readout. This is the fastest readout mode, but means that each row of the sensor acquires data for a different time period. In Rolling mode the exposure time is determined by the row readout time, and cannot be independently controlled. In Global mode all pixels acquire for the same time period and are then read out. The exposure time is independent of the readout time, and can be as short as 9 microseconds on the Neo.
A3_SHUTTER_MODE A3ShutterMode, A3ShutterMode_RBV mbbo, mbbi
Andor3FrameRate asynFloat64 R/W Frame rate. This is the reciprocal of ADAcquirePeriod, and is the units used to control the Andor cameras. There are two limitations on the frame rate:
The maximum rate that the sensor can be read out into the RAM on the camera head. The driver will limit the FrameRate to this value in all cases. This value can be obtained for the current acquisition settings by typing “asynReport 1” to get a detailed report from the Andor3 driver.
The maximum sustained frame transfer rate that the interface (e.g. CameraLink card) can support. This value is contained in the TransferRate PV. It is permissible to exceed this value for a limited number of frames, allowing the frames to accumulate in the camera head RAM. The number of frames that will fit in the camera head RAM is controlled by the PixelEncoding and the AOI parameters (A3Binning, SizeX, SizeY). If the camera head RAM fills up the acquisition will hang, and must be stopped and restarted.
A3_FRAME_RATE FrameRate, FrameRate_RBV ao, ai
Andor3TransferRate asynFloat64 R/O The maximum transfer rate in frames/s of the interface (e.g. CameraLink card). This is the maximum sustained FrameRate which can be achieved. A3_TRANSFER_RATE TransferRate ai
Andor3PreAmpGain asynInt32 R/W Controls the pre-amp gain and readout mode. Choices for the Neo are:
0 = 11-bit (high well capacity)
1 = 11-bit (low noise)
2 = 16-bit (low noise & high well capacity)
A3_PRE_AMP_GAIN PreAmpGain, PreAmpGain_RBV mbbo, mbbi
Andor3PixelEncoding asynInt32 R/W Controls the pixel encoding. Choices for the Neo are:
0 = Mono12
1 = Mono12Packed
2 = Mono16
9 = Mono32
Mono12 and Mono12Packed are only available when PreAmpGain is one of the 11-bit modes.
A3_PIXEL_ENCODING PixelEncoding, PixelEncoding_RBV mbbo, mbbi
Andor3ReadoutRate asynInt32 R/W Controls the ADC readout rate. Choices for the Neo are:
0 = 100 MHz
1 = 200 MHz
2 = 280 MHz
A3_READOUT_RATE ReadoutRate, ReadoutRate_RBV mbbo, mbbi
Andor3ReadoutTime asynFloat64 R/O The readout time from the sensor into camera RAM. A3_READOUT_TIME ReadoutTime ai
Andor3Overlap asynInt32 R/W Controls whether acquisition and readout are overlapped. Choices are 0 (No) and 1 (Yes). On the Neo if Overlap=Yes then the minimum exposure time is limited to about 10 ms. If Overlap=No then the minimum exposure time is 9 microseconds. A3_OVERLAP Overlap, Overlap_RBV bo, bi
Andor3NoiseFilter asynInt32 R/W Controls whether the firmware applies the Spurious Noise Filter. Choices are 0 (No) and 1 (Yes). A3_NOISE_FILTER NoiseFilter, NoiseFilter_RBV bo, bi
Trigger control
Andor3SoftwareTrigger asynInt32 R/W Writing 1 to this record generates a software trigger if TriggerMode=Software. A3_SOFTWARE_TRIGGER SoftwareTrigger bo
Area-Of-Interest (AOI) Control
Andor3FullAOIControl asynInt32 R/O Indicates whether this camera supports full AOI control. This is Yes for the Neo. A3_FULL_AOI_CONTROL FullAOIControl bi
Andor3Binning asynInt32 R/W Controls the binning. The binning on the sCMOS camera is done in firmware and only certain preset values are allowed. Choices for the Neo are:
0 = 1x1
1 = 2x2
2 = 3x3
3 = 4x4
4 = 8x8
A3_BINNING A3Binning, A3Binning_RBV mbbo, mbbi

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

Unsupported standard driver parameters

ColorMode, ReverseX, and ReverseY are currently not supported.


If any of the parameters set are out of range the driver will set them to the minimum or maximum allowed value for that parameter. The _RBV value will indicate the actual value in effect.


The Andor3 driver is created with the andor3Config command, either from C/C++ or from the EPICS IOC shell.

int andor3Config(const char *portName, int cameraId,
                int maxBuffers, size_t maxMemory,
                int priority, int stackSize, int maxFrames)

For details on the meaning of the parameters to this function refer to the detailed documentation on the andor3Config function in the andor3.cpp documentation and in the documentation for the constructor for the andor3 class. The maxFrames parameter controls the number of frame buffers the driver queues to the SDK when acquiring data. The default value is 10. Increasing this number will allow the SDK to transfer images from the camera at the full interface speed even when the driver is not reading them that quickly. This will help to prevent frames from filling the camera RAM when operating close to the maximum interface transfer rate (=TransferRate).

There an example IOC boot directory and startup script (iocBoot/iocAndor3/st.cmd) provided with areaDetector.

MEDM screen

The following shows the MEDM screen that is used to control the Andor detector. Note that the general purpose screen ADBase.adl can be used, but it exposes a few controls that are not applicable to the Andor, and lacks some fields that are important for the Andor.

Andor3.adl is the main screen used to control the Andor driver.




There is currently no way to query the driver to know how much memory remains in the on-board RAM. When the RAM fills up the camera stops acquiring images.