areaDetector MarCCD driver

Table of Contents

• Introduction
• Implementation of standard driver parameters
• MarCCD specific parameters
• Unsupported standard driver parameters
• Configuration
• MEDM screens
• Performance measurements
• Restrictions

Introduction

This is an EPICS areaDetector driver for the Rayonix (formerly MarCCD) detectors from Rayonix/MarUSA.

The interface to the detector is via a TCP/IP socket interface to the marccd_server_socket server that Rayonix provides. The marccd_server_socket program must be started before the areaDetector software is started, by running the marccd program and executing Acquire/Remote Control/Start.

marccd must be using Version 1 (for non-HS detectors) or 2 (for HS detectors) of the remote protocol. This is normally done done by editing the file marccd/configuration/marccd.conf and replacing the line

include marccd_server_v0.conf
    

with

include marccd_server_v1.conf
    

The file marccd_server_v1.conf should contain the lines:

remote_mode_server_command /home/marccd/contrib/marccd_server/marccd_server_socket
remote_mode_server_arguments 2222
    

The first line points to the location of the marccd_server_socket program that is used to implement remote control. In order to work with the areaDetector driver this must be a version of this program created after November 11, 2008 when support for the get_frameshift command was added. A recent version of this program can be downloaded from the Rayonix FTP site.

The marccd program saves the data to disk as TIFF files. The areaDetector software reads these disk files in order to read the data, because marccd does not provide another mechanism to access the data.

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 MarCCD detectors. The marCCD class documentation describes this class in detail.

Implementation of standard driver parameters

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

It is useful to use an NDPluginStats plugin set to use the entire marCCD detector. The MaxValue_RBV PV can be monitored to make sure that the 16-bit limit of 65,535 is not being approached in any pixel.

MarCCD specific parameters

The MarCCD driver implements the following parameters in addition to those in asynNDArrayDriver.h and ADDriver.h. Note that to reduce the width of this table the parameter index variable names have been split into 2 lines, but these are just a single name, for example marCCDState.

Unsupported standard driver parameters

The MarCCD driver does not support the following standard driver parameters because they are not supported in the marccd program:

• Number of exposures per image (ADNumExposures)
• Gain (ADGain)
• Region to read out (ADMinX, ADMinY, ADSizeX, ADSizeY, ADReverseX, ADReverseY)
• Data type (NDDataType)
• Reading previous files (NDReadFile)
• Capture or stream file saving (NDFileWriteMode, NDFileCapture, NDNumCapture, NDNumCaptured)

Configuration

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

int marCCDConfig(const char *portName, const char *serverPort,
                 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 mar345Config function in the marCCD.cpp documentation and in the documentation for the constructor for the marCCD class.

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

MEDM screens

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

marccd.adl is the main screen used to control the MarCCD driver.

marccd.adl

marccdAncillary.adl is the screen used to input ancillary information that is written to the MarCCD TIFF files.

marccdAncillary.adl

asynRecord.adl is used to control the debugging information printed by the asyn TCP/IP driver (asynTraceIODriver) and the EPICS device support (asynTraceIODevice).

asynRecord.adl

asynOctet.adl can be used to send any command to the marccd remote server and display the response. It can be loaded from the More menu in asynRecord.adl above.

asynOctet.adl

Performance measurements

The following measurements were done to demonstrate the performance that can be obtained with the areaDetector MarCCD driver. These measurements were made with a MAR-165 CCD. The EPICS IOC was running on the same Linux machine as the marccd program. The acquisition time was 1 second.

Restrictions

The following are some current restrictions of the MarCCD driver:

• The marccd program can save files in many different formats, with TIFF being the default. The areaDetector driver can only read TIFF files, not other formats.
• The areaDetector driver can in principle be run on machines other than the Linux machine running marccd, since the connection is via a socket. It has only been tested on Linux.
• The MarCCD driver keeps retrying to read each TIFF file until the modification date of the TIFF file is after the time that the exposure command was issued. If it did not do this check then it could be reading and displaying old files that happen to have the same name as the current files being collected. This check requires that the computer that is running the soft IOC must have its clock well synchronized with the clock on the computer on which the files are being written (i.e. the computer generating the file modification time). If the clocks are not synchronized then the files may appear to be stale when they are not, and the driver will time out. The driver actually tolerates up to 10 second clock skew betweeen the computers but any more than this may lead to problems.
• The following items are hardcoded in the driver. They can be changed by recompiling compiling if necessary.
  • MAX_MESSAGE_SIZE=256 The maximum size of message to/from marccd_socket_server.
  • MAX_FILENAME_LEN=256 The maximum size of a complete file name including path and extension.
  • MARCCD_SERVER_TIMEOUT=1.0 Timeout when communicating with marccd_socket_server.
  • FILE_READ_DELAY=.01 seconds. The time between polling to see if the TIFF file exists or if it is the expected size.
  • MARCCD_POLL_DELAY=.01 seconds. The time between polling the marccd_socket_server status to see when a task has completed.