DAQ system

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Figure 1. DAQ System circled in red; one rack for each of the four "hemispheres" of Gammasphere

Gammasphere's DAQ system (data acquisition system) is now placed on relay racks by each side of its "hemispheres". Each of the racks for the DAQ consists of a power supply, a collector box, and a VME crate. The data acquisition system observes, interprets, and modifies data taken from Gammasphere and appropriately presents it to the user.

The picture above provides an overall map to the naming conventions associated with the system. Cardinal directions are shown in purple text, process variable (EPICS) names are shown in green text and network IDs are shown in red text. There are multiple computers within the DAQ system:

Network names and IP addresses of the devices within Digital Gammasphere

Network name	IP address	Description
ioc01:	192.168.203.141	MVME5500 VME processor used for control and readout
ioc02:	192.168.203.142	MVME5500 VME processor used for control and readout
ioc03:	192.168.203.143	MVME5500 VME processor used for control and readout
ioc04:	192.168.203.144	MVME5500 VME processor used for control and readout
ioc05:	192.168.203.145	MVME5500 VME processor used for control and readout
ioc06:	192.168.203.177	MVME5500 VME processor used for control and readout
ioc07:	192.168.203.178	MVME5500 VME processor used for control and readout
ioc08:	192.168.203.179	MVME5500 VME processor used for control and readout
ioc09:	192.168.203.180	MVME5500 VME processor used for control and readout
ioc10:	192.168.203.183	MVME5500 VME processor used for control and readout
ioc11:	192.168.203.181	MVME5500 VME processor used for control and readout
ioc12:	192.168.203.182	MVME5500 VME processor used for control and readout
gs-cne	192.168.203.88	Raspberry Pi inside the North East Collector box
gs-cnw	192.168.203.149	Raspberry Pi inside the North West Collector box
gs-cse	192.168.203.42	Raspberry Pi inside the South East Collector box
gs-csw	192.168.203.26	Raspberry Pi inside the South West Collector box
gs-pdu-north	192.168.203.224	Power Distribution Unit for the North Hemisphere
gs-pdu_south	192.168.203.225	Power Distribution Unit for the North Hemisphere
gs-ts-north	192.168.203.91	Terminal server providing console port access for ioc07 through ioc12
gs-ts_south	192.168.203.186	Terminal server providing console port access for ioc01 through ioc06
ln2con	192.168.203.148	Linux computer that controls and monitors the liquid nitrogen fill system
lnfill	192.168.203.121	Embedded VME processor that hosts the EPICS databases for valve status and valve control

When Gammasphere collects data, single-ended signals are first collected from the slope box for the Ge Center, Ge Sides, and BGO segment. The signals are converted to differential signals by the SBX, and are then sent to the collector box so the signals can properly be routed to the digitizers. The digitizers process and output the desired information to the user based upon their data specifications. The DAQ system is an FPGA-based design that provides communication hub interfacing the preamp, power board, dongle and slope box to EPICS through serial interface. Analog signal paths are completely software controlled.

DAQ System Function

The DAQ system prior to upgrades consisted of VME crates, IOC Modules, Digitizers and Trigger Modules. There were two types of Digitizers (Master and Slave) and well as Trigger (Master and Router). In the current version of the upgraded Gammasphere DAQ system, some of the old hardware is still used, but in a different way. All channels in all digitizers run continuously. When discriminator logic marks leading edges of gamma-ray signals, energy sums, timing and other data are stored in a header identifying the event. If the event is selected for readout by the trigger system, the header and a programmable amount of waveform is transferred from the channel to the board-wide FIFO (first in, first out) data holder. The IOC scans the FIFOs to see if there is data to read out. If so, the IOC reads it out into buffers. A program called “gtReceiver” sends messages to each IOC when the receiver is ready for more data. The IOC then breaks apart buffers into UDP packets and sends them to gtReceiver. The gtReceiver program then routes the packets to files that may be organized by digitizer or by channel.

Figure 2. Diagram of the DAQ system process.

To view how this system is controlled, go to DGS Commander EDM Screens.

Go back to Digital Gammasphere Upgrade Project