The EGSE hardware is released 6 times during LAT development as shown in the last section on schedule. These releases include 4 separate configurations: Engineering Model 1, Engineering Model 2, Qualificaiton Unit, and Flight Unit.
Function Rev EGSE Number Development support EM1 TEM Interface/WS 2 Subsystem support EM1 TEM Interface/WS 6 Integration Testing EM1 TEM Interface/WS 2 SLAC DAQ H/W development EM2 SIS/WS/IPS 1 FSW Testbed EM2+ SIS/WS/IPS 1 Calibration/Qualification QU SIS/WS/IPS 1 Flight I&T FU SIS/WS/IPS 1
Electrical Ground Support Equipment configurations
The first hardware release of the EGSE is to suport the development of the Tower Electronics Module (TEM). When the TEM is ready, it will be delivered to the subsystems to support sensor development. Each TEM delivered to a subsystem will come with EM1 EGSE: a PCI crate with 603e CPU, communications card, and a custom interface card to the EM1 TEM. The custom interface card will probably be a Xylinx FPGA with LVDS interface chips on it. It will handle data acquisition, possibly using a National LVDS serializer chip, and also simulate the global trigger. The E&DAQ group provides the custom interface card. The EGSE team buys the COTS PCI bus and 603e CPU. The CPU acquires data via the custom card from the TEM and exports the data over the ethernet. The EGSE incldues a Sun (or possibly Linux) workstation provides commanding, data acquisition, data archive, data display, and data distribution. It also has to support the 603e software development environment which is probably VxWorks with a license server at SLAC. A separate Sensor simulator card is being developed to provide a stimulus for the TEM in the absense of the actual sensor. This simulator is provided by the E&DAQ group. The current estimate of EM1 TEM/EGSE systems and their distribution is listed below.
Subsystems CAL NRL 2 ACD GSFC 1 TKR SLAC 1 Italy 1 UCSC 1 Development DAQ SLAC 1 HEPL 1 Integration I&T SLAC 2
Engineering Model 1 Electrical Ground Support Equipment configuration
EM2 is the first release of the complete Trigger and Dataflow (T&DF) system which supports multiple towers. EM2 will include a non-flight version of the LAT data acquisition system including the Global Trigger, Event Processor and Spacecraft Interface Unit (SIU). The SIU will probably be a PCI based box with a 603e cpu, National 216 serializer for high speed science data, MIL-STD-1553 for command and housekeeping interface to the spacecraft Command and Data Handling system (C&DH).
The EGSE then becomes a S/C Interface Simulator (SIS) which interfaces to the SIU and provides switched power, analog and discretes, serializer receiver, and 1553 master. This SIS is probably one of the previously purchased PCI crates with a 603e CPU, MIL-STD-1553, and COTS I/O card in it. The SIS provides the interface to the ethernet which then links to the Sun (Linux) support workstation. Paired with the SIS is an Instrument Power Supply (IPS) which provides 24-34 VDC power under computer control.
Engineering Model 2 Electrical Ground Support Equipment configuration
Once the EM2 T&DF is shown to work, the TEMs are replicated to develop a full, 16 module software testbed. The testbed will include an EM version of the SIU. Similarly, the SIS will be replicated so that the E&DAQ development team holds onto one for hardware development while the testbed gets the second to support software development. The testbed includes enough sensor simulators to exercise a full scale T&DF system with reasonable approximation to the expected orbital event rates. The EGSE workstation is provided with sufficient hard disk and tape backup capability to archive testbed data.
The next DAQ release is for the calibration/qualification towers. The T&DF system will include TEMs to support up to 4 tracker/calorimeter towers and one ACD, a Global Trigger, Event Processor, and an SIU. The system will run in parallel with the FSW testbed and so will need its own SIS, IPS, and EGSE workstations. It is highly probable that this EGSE system will need to travel with the Qual/Cal unit during environmental or beam testing. It will therefore include two workstations to provide a hot spare as well as to segment to commanding and data archive tasks from the data display and analysis tasks.
The Flight Unit T&DF will also operate in parallel with the Testbed and the Qual/Cal Unit resulting in the requirement for another set of EGSE. The EGSE-FU will include a SIS, IPS, and two workstations.