System Level
The electronic systems of FOCE consist of a main electrical housing, three junction boxes, a variety of scientific and engineering instruments, and all necessary interfacing cabling. FOCE is tethered to MARS via a 30 meter umbilical cable which provides ethernet connections and +375Vdc. The main electrical housing contains all of the computer systems and peripheral hardware needed to interface with the scientific instruments. Included in the main housing is the power distribution, computer stack, and a variety of communication interfaces (USB, serial, video server). The junction boxes serve as a distribution interface between the instruments and the main housing.
Electrical Block Diagram Concept
Mars Interface
The FOCE experiment will reside on the ocean floor within 30 meters of the MARS science node. The electronics housing will be connected to MARS with a cable from Falmat connectorized on one end with a 12-way ODI and a MINK-16-CCP on the other.
Electronics Housing
The electronics for the FOCE experiment will reside in the housing originally deployed with DORISS. It is a cylindrical vessel with an internal diameter of xx and length of yy, resulting in a usable volume of zz. The housing has a collar with 8 water resistant connectors which attach to the junction boxes. The other end will be a domed cap with no electrical fittings. A side port, previously used for a camera with DORISS, will be capped off.
The junction box is the same type as used on the Tiburon replacement vehicle. It is a plastic cylindrical shell with a removal internal basedboard. The junction box will have 9 Dorn syle fittings and 4 FCR style bulkhead connections. The terminal strips will be mounted on the baseboard.
Electronics Housing Wiring Diagram RevB
DigiPort TS MEI Quad Serial Server
HTM2500 Temp & Humidity Sensor
Cabling
Electronics Housing to Junction Box Cable
Computer Stack
The computer for FOCE is a PC/104 stack consisting of seven individual boards. It consists of a main CPU board, a 1:4 ethernet switch, an octal serial expander, a 16-channel relay board, a data acquisition boad, a system health monitor, and a power supply. The computer stack is responsible for the main FOCE control loop, data acquisition, and remote control of the onboard digital camera.
The CPU board is a Lippert Cool RoadRunner-LX800 PC/104-Plus single board computer. It is a CPU board with LCD+VGA, CRT, AMD GEODE LX800@0.9W (500 MHz), up to 1GB DDR SDRAM, 4x USB2.0, IrDA, RTC, GoldCap, EIDE, 3x COM, LPT, PS/2 keyboard and mouse, watchdog, PC/104 bus, PC/104+ bus, VGA controller, TFT, bitparallel and LVDS interface, Fast Ethernet 100/10BaseT, 8Bit GPIO, Compact Flash Type II Socket, and AC97 sound.
The hard drive is a Seagate Momentus 5400.3 160GB Notebook drive.
The serial expander is a ConnectTech Inc Xtreme/104-Plus Octal Serial Expander.
The relay board is a Real Time Devices DM6952HR Power Relay Output Module.
The data acquisition board is a Diamond-MM-32x-AT Analog/Digital Input/Output Module.
The PCI104 Bus system health monitor is a Tri-M Engineering HM-PCI104 Health Monitor.
The PC/104 Bus system health monitor is a Tri-M Engineering HMPC104 Health Monitor.
The power supply is a Tri-M Systems HE104+DX 108 Watt Power Supply.
The auxilliary board contains additional circuitry for data acquisition scaling and miscellaneous functions.
System Power
Input power to FOCE is +375Vdc supplied by the MARS node. It is downconverted to +24Vdc and +12Vdc by a pair of DC-DC Converters from Vicor. The 375-24V converter is rated at 600W and the 375-12V converter is rated at 150W.
375Vdc to 24Vdc Maxi DC-DC Converter
375Vdc to 12Vdc Micro DC-DC Converter
