DigitalLynxSX Acquisition Amplifier

Hardware Overview

The Digital Lynx SX Acquisition Amplifier is a stand alone acquisition system.  The DigitalLynxSX Acquisition Amplifier consists of a chassis that contains input boards and HRS boards.  The total number of boards it can hold is 16.  Each board has 32 AD channels associated with it.  Channel numbers increment starting  from the left side of the chassis.  A signal is input into each input board via a DRS board or directly into a combo board.  The signal is digitized and then formatted and sent over the fiber optic cable to the fiber optic Ethernet card located in the  PC. This Ethernet card needs to be configured for 'Jumbo Packets' (9014 bytes) and with 'Flow Control' disabled.

Hardware Sub System Interface

In order to retrieve data from the fiber optic Ethernet card , a hardware sub system (HWSS) must be created.  A hardware sub system is an object in __prod_name that controls the acquisition of data from a specified piece of hardware, in this case the DigitalLynxSX Acquisition Amplifier.  The hardware sub system has a set of properties that control how data is retrieved and processed.   The creation and properties for a sub system can only be accessed using configuration file commands.   
The -CreateHardwareSubSystem command is used to create a new hardware sub system.  As part of the creation command, a name must be given to the sub system.  The name must be unique and is used to report errors or to set the properties of the sub system.

Once a sub system is set up, its first responsibility is to retrieve data from the hardware and store it in a buffer.  In some instances, buffers may fill up faster than the data in them can be processed by the rest of the system.  If this occurs, we have what's called a buffer overrun error and some data will be lost.

The user has the option to save the unfiltered data coming from the hardware sub system to a raw data file.  This file must be specified by the user, __prod_name will only save data to this file if it has been requested to.

The next step is to process the data that resides in our buffers.  When data is acquired by the DigitalLynxSX Acquisition Amplifier, it is packed into a record and then sent to the fiber optic Ethernet interface.  The data now has to be unpacked and its validity checked.  The first step is to find a valid record, this is called hunting.  A couple things are checked during the hunting process to determine if a record is valid.  The first thing is to check to see if the id associated with the record is valid.  The next thing is to see if the record size is valid.  The record size is determined by the number of boards in the DigitalLynxSX Acquisition Amplifier chassis.  The last thing that is done is a check to make sure the data has not been corrupted .   If any of these checks fail, then a hunt error is reported to the System Status Dialog.  Now that we know we have a valid record, the timestamp is checked to make sure it is incrementing.  If it is not incrementing, the record may be reordered based on its timestamp or an error is generated.

The record has now been validated.  The last step is to unpack the data from the record and store it into a buffer that will be sent to have DSP filters run on it.  The hardware sub system will continue to process records until acquisition is turned off.

TTL Input and Output

The DigitalLynxSX Acquisition Amplifier has built in support for bidirectional TTL use. The direction of the TTL port can be changed in the Digital IO Setup.  The Board Number is the value used when __prod_name assigns the device name used to reference the TTL device.  For more information, see the Digital I/O Overview.

Port Label	Board Number	Total TTL Bits	Number of Ports	Number of Bits per Port	Port Direction
TTL Port	0	32	4 or 2	8 or 16	Bidirectional

The digital IO board can operate with 4 ports with 8 bits (default) or 2 ports with 16 bits each. This can be changed using the -SetDigitalIOBitsPerPort command. See Digital I/O Commands for how to use this command.

Hardware Input Calibration

A DC offset value and gain value may be specified to help normalize signal amplitude for data coming from the ATLAS Acquisition Amplifier. The offset value will be subtracted from each data point and the gain value will be multiplied by each data point. The subtraction will come first, followed by the multiplication. This will be done before data is filtered or output to a Raw Data File. A pair of offset and gain values may be applied to each AD channel in the system. The default offset value for each channel will be 0 and will be an integer value. The default gain for each channel will be 1.0 and will be a decimal value. A message will be output to the log file when these values are modified. These values will be stored to settings and configuration files.


DigitalLynxSX Acquisition Amplifier System Topics :

DigitalLynxSX Acquisition Amplifier Properties Dialog
DigitalLynxSX Acquisition Amplifier Commands