Research Article CIB: An Improved Communication...

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 185769 12 pageshttpdxdoiorg1011552013185769

Research ArticleCIB An Improved Communication Architecture forReal-Time Monitoring of Aerospace Materials Instrumentsand Sensors on the ISS

Michael J Krasowski1 Norman F Prokop1 Joseph M Flatico2 Lawrence C Greer1

Phillip P Jenkins3 Philip G Neudeck1 Liangyu Chen2 and Danny C Spina4

1 NASA Glenn Research Center 21000 Brookpark Road Cleveland OH 44135 USA2Ohio Aerospace Institute NASA Glenn Research Center 21000 Brookpark Road Cleveland OH 44135 USA3U S Naval Research Laboratory 4555 Overlook Avenue SW Washington DC 20375 USA4 Jacobs Technology NASA Glenn Research Center 21000 Brookpark Road Cleveland OH 44135 USA

Correspondence should be addressed to Norman F Prokop normanfprokopnasagov

Received 12 April 2013 Accepted 4 June 2013

Academic Editors T E Matikas and M R Woike

Copyright copy 2013 Michael J Krasowski et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The Communications Interface Board (CIB) is an improved communications architecture that was demonstrated on the Interna-tional Space Station (ISS) ISS communication interfaces allowing for real-time telemetry and health monitoring require a signifi-cant amount of developmentTheCIB simplifies the communications interface to the ISS for real-time healthmonitoring telemetryand control of resident sensors or experimentsWith a simpler interface available to the telemetry bus more sensors or experimentsmay be flownTheCIB accomplishes this by acting as a bridge between the ISSMIL-STD-1553 low-rate telemetry (LRT) bus and thesensors allowing for two-way command and telemetry data transfer The CIB was designed to be highly reliable and radiation hardfor an extended flight in low Earth orbit (LEO) and has been proven with over 40months of flight operation on the outside of ISSsupporting two sets of flight experiments Since the CIB is currently operating in flight on the ISS recent results of operations will beprovided Additionally as a vehicle health monitoring enabling technology an overview and results from two experiments enabledby the CIB will be provided Future applications for vehicle health monitoring utilizing the CIB architecture will also be discussed

1 Introduction

The International Space Station is a unique space vehicle inthat it is currently the largest artificial satellite in orbit aroundthe Earth The U S portion of the ISS has been designatedas a national laboratory by the Congress The ISS providesa unique environment of extreme hot-cold thermal cyclingcosmic radiation exposure [1] atomic oxygen presence vac-uum and microgravity This allows for long duration exper-iments and space testing of devices and structures Whiletesting and experiments take advantage of this unique envi-ronment facility equipment must operate reliably in it Elec-tronic components and integrated circuits (IC) are especiallysusceptible to radiation effects from the environment in LEOThese effects can present themselves in two ways long-term

dose damage associated with total ionizing dose (TID) orthrough single event effects (SEE) Long-term or TID resultsin permanently damaging an IC by altering the crystal latticeof the semiconductor which can result in changing biasvoltages and currents which affect circuit operation Wheresingle event upsets (SEU) are transient energy is transferredfrom ionizing particles to the IC This energy transfer islocalized so individual transistors on an IC are affectedSingle events caused by radiationmay only result in the flip ofa single bit or the corruption of an analog signal If an affectedbit is part of an instruction for microcontroller or processorthe result could result in operational failure Further an SEE-induced phenomenon known as a single event latchup (SEL)could also result in a loss of data but in extreme cases maycause a hard destructive failure which could result in the

2 The Scientific World Journal

permanent loss of a circuit component With this in mindcare must be taken in the design of any electronic systemexpected to operate reliably on the ISS for extended period oftime and be tolerant of the expected radiation environment

To support science payloads the ISS as a facility providesthree telemetry communications interfaces [2] for residentexperiments with its associated physical layerprotocol lowrate data link MIL-STD-1553 medium rate data link Ether-net and high rate data link fiber optic Each interface canprovide telemetry to the ground Increased bandwidth comeswith increased cost in development tomeet the physical inter-face requirements The only interface available throughoutthe ISS is the MIL-STD-1553 bus In addition to telemetrydata the Mil-STD-1553 bus performs the command healthand status data transferThis is done for safety reasons so thathealth and status data are transmitted on the most reliablecommunication bus

The MIL-STD-1553 [3] ldquoAircraft Internal Time DivisionCommandResponse Multiplex Data Busrdquo defines a physicallayer as well as a bus protocol The MIL-STD-1553 bus ishighly reliable and robust in that it is a deterministic com-mand and response protocol The ISS adds additional layersto those of the MIL-STD-1553 standard in effect makingthe ISS MIL-STD-1553 implementation a superset of themilitary standardWhich allows ISSMIL-STD-1553 hardwareto interface with other space and aircraft platforms but notnecessarily the converse The MIL-STD-1553 bus is deployedon numerous U Smilitary aircrafts including the F-16 FalconFA-18 Hornet AH-64 Apache and P-3C Orion and hasalso been adopted by North Atlantic Treaty Organization(NATO)TheMIL-STD-1553 bus transmits data at 1Mbitsec-ond The command and response protocol of the bus addsoverhead reducing the effective bit rate for data transfer Inaddition the ISS adds overhead to the bus transfers Onelayer added by ISS to theMIL-STD-1553 telemetry is the Con-sultative Committee for Space Data Systems (CCSDS) head-ers which allow for data telemetry routing in space Eachnode in the telemetry system is provided with a unique appli-cation identifier (APID) which is part of the CCSDS headerto enable routingThese APIDs allow a user on the ground toreceive telemetry and command their node from anywherewith internet connectivity The ISS allots 128 kBytes of tele-metry data per second some of which is used for overheadThe ISS allows commands from the ground to be routed toAPIDs residing on the MIL-STD-1553 bus

Onboard the ISS there is an Express Logistics Carrier(ELC) facility which is primarily designed to store ISSreplacement parts but also has two science payload slots perplatform [4] Each science payload site has 28V and 120Vpower available A MIL-STD-1553 communications repeater(bus controller) link to the ISS is also provided by the ELCallowing telemetry data to pass through

The CIB was needed to be the communications backbonefor a permanent testbed on the ELC of the ISS which wouldutilize the ISS telemetry of the MIL-STD-1553 bus TheCIB needed to provide simpler communication interface toexperimenters while maintaining the reliability expected ofa space flight system on the ISS The CIB needed to bedesigned with radiation tolerance and reliability as primary

considerations The CIB was designed by the NASA GlennResearch Center (GRC) Mobile and Remote Sensing (MaRS)Laboratory The first experiment set to utilize the testbedwas the Materials on the International Space Station Seven(MISSE7) [5] MISSE7 was comprised of numerous passiveexperiments and over 21 active experiments using the com-mand and telemetry capabilities provided by theCIBMISSE7used two Extra-Vehicle Activity (EVA) deployable suitcase-like containers called a Passive Experiment Container (PEC)in which numerous experiments are contained These PECsare carried by astronauts opened and mounted on the ELCWhen the experiment was completed an additional EVAwasused to retrieve the PECs and install a new one for the follow-on experiment setMISSE8This exchange required a physicalcommunications link which was swappable The need foron-orbit exchange of PECs required a physical communi-cations link robust enough to withstand potential damageencountered during the swap

The CIB was installed during Space TransportationSystem-129 (STS-129) and is currently flying on the exteriorof the International Space Station mounted on the ExpressLogistics Carrier 2 (ELC-2) The CIB provides a simple RS-485-based communications interface between experimentsinstruments or sensor systems and the ELCrsquos MIL-STD-1553bus This allows developers to design on simple platformswithout having to confront the difficulty of integrating theirexperiments directly into the ELC or the ISS The CIBcurrently provides serial communication supporting twentyactive systems Figure 1 shows the CIB within the MISSE7communication architecture including the interface to theISS telemetry through the ELC Follow-on experiments(MISSE8) leave the CIB in place and swap out one or bothof the allowed PECs

This paper will discuss in detail the technical devel-opment and design of the CIB hardware and architectureRecent results from current operations aboard the ISS will beprovided Specific experiments supported by the CIB like aSilicon Carbide Junction Field Effect Transistor (SiC JFET)health monitoring and a solar cell health monitoring will bediscussed Future health monitoring applications to includenode to node schemes will also be briefly discussed

2 CIB Design

The CIB is designed to be a highly reliable and radiationhard communications bridge from the ISSELC MIL-STD-1553 to onboard experiments sensors and health monitoringsystems The CIB is constructed from components designedor known to be radiation tolerant of LEO conditions for over20 years of operation Further the CIB is designed to be toler-ant of the electrostatic discharge (ESD) anticipated to occurduring removal and insertion of new payload systems overmultiple missions

Communications over each RS-485 bus was limited to9600 baud which is 9600 bits of data per second for eightbit words Though theoretically capable of at least ten timesthis bandwidth the CIBwas designed for 9600 baud as a con-sequence of some experiments in MISSE7 being only capableof that rate due to hardware or software constraints Thus

The Scientific World Journal 3

ExpressLogisticsCarrier(ELC)

Downlinktelemetry

Uplinkcommandcontrol

InternationalSpace

Station(ISS)

MIL-STD-1553 MIL-STD-1553CommunicationsInterface Board

(CIB)RS-485 bus

Passive ExperimentContainer (PEC)

Experiment 1Experiment 2

SIC JFET experimentFTSCE II

Experiment n

MISSE7delivered on STS-129

Figure 1 Diagram of theMISSE7 communication architecture and interface to the International Space Station telemetry through the ExpressLogistics Carrier

the lowest common denominator dictated bus speed Areprogrammed CIB could support higher baud rates andcould dynamically change baud rate to accommodate eachexperiment A block diagram of the CIB interfaced to a stringof experiment systems is given below in Figure 2 Note thatall systems interface to the CIB via a full duplex RS-485bus system and each system has associated with it a uniquehardware enable line

3 Hardware Interface

The RS-485 standard specifies a multidrop serial bus whichcan be full or half-duplex The CIB implements a full duplexmultidrop bus where each experiment or sensor is a stub ordrop on the bus and reception and transmission happen onseparate lines Since MISSE7 was to support two physicallyseparate experiment containers the designers provided twoRS-485 buses from the CIB one for each container Themultidrop bus provides a concern for reliability as one erranttransceiver can corrupt the bus To mitigate against this riskthe CIB implements a hardware transmission enable as wellas requiring a software enable function on the experimentside

Experimenters must provide a hardware handshakinginterface as shown in Figure 3 wherein the enable line fromthe CIB is shown schematically to provide one half of asignal set necessary to enable a systemrsquos transmit hardwareThe second half of the signal set is provided by the systemthrough response to an initiating packet transfer from theCIB on the RS-485 bus containing the systemrsquos APID Thisinterface prevents experiments from transmitting withoutbeing selected and communicated to by theCIBThe interfacemust be implemented in hardware so that the experimentcannot interfere with the RS-485 bus during communicationsslots not associated with it The cause of this out of order bususe could be the result of a software failure for example TheCIB maintains a permission bitmap that can be overwrittenby a command from the ground If a given experiment islocked out via the bitmap (for any number of schedulingreasons or after detection of system failure) its enable is neverasserted and is prevented from communicating

This transmission scheme allows for the full duplex hard-ware Universal Asynchronous Receiver Transmitter (UART)common to most microcontrollersmicrocomputerscompu-ters or which can be easily configured into programmablelogic or as a software UART routine on microcontrollerswhich allow for interrupt on transition Thus systems maybe easily configured using simple and available hardware anddesign tools

The byte format is 8 bit one start bit stop bit and noparity The baud rate is 9600 which simplifies requirementsfor the simpler hardware and offer forgiveness in timing anddeskew

The CIB rotates around through its list of 20 APIDSpolling each experiment one at a time in order as long aspower is appliedThis method is chosen as the desired way tomaximize bandwidth for the experiments If a system needsto pass more than one packet set of data it merely waits untilthe CIB returns to it at a later time

In addition to the transmission lines (TX) receive lines(RX) +5Volt power and ground are the enable lines for theexperimentsWithin the example experiment hardware is thelogic to enable failsafe transmission on the shared RS-485 busas required by the CIB Interface Control Document [6] Theseparate enable wire provided to each experiment is detailedin the following illustration in Figure 4

An enable line is pulled low for a particular system priorto the CIB transmitting to that system A 10Volt transientabsorber (dual redundant 5 volt transient absorbers) and a1 kΩ resistor occupy the output of each enable line as shownin Figure 4 and are present to mitigate against electrostaticdischarge and also to a short to +28 condition should it occurat an experiment As noted earlier the enable wire is usedby the system to enable its transmitter hardware if it has alsoreceived a valid packet from the CIB Commencement of thepacket transfer fromCIB occurs no less than 250ms from theassertion of enableThis enable signal removes the obligationof the systems fromhaving tomonitor all the traffic on the TXlinewhile listening for transmissions dedicated to themselves

Also this active low enable signal can be used to locallyenable a pass element to provide the system power Thus anexperiment may come alive upon a powerup initiated by this


Dual redundant MIL-STD-1553 bus to ISS

Data device corpBU-63825D1-110

Glue logic54ACXX

Data ADDR

ADDR

ADDR

DataCTRL

CTRL

CTRL

TXRXUA

RT80

C32E

-30

mic

roco

ntro

ller

IO p

orts

Dec

ode

Dec

ode

AT28

C010

EEP

ROM

ENB0

ENBn

ENB0

ENBn

Common

Ground returnline to experiments

1 ton ENABLE linesbus to experiments

RCV+RCVminus

XMIT+

XMITminus

Shield

Serial communicationsbus to experiments

DS16F95

DS16F95

Dual1of2

MUXSelect

Bankselect

INSTRPEC

CIB

M65

608E

128

Ktimes8

SRA

M

D

D

Experiment Experiment Experimentnumber 1 number 2 number nmiddot middot middot

Figure 2 A block diagram of the Communications Interface Board (CIB) interfacing between the International Space Station (ISS) MIL-STD-1553 bus and the experiments residing on the Passive Experiment Container (PEC) (image courtesy of NASA)

An example schematic for experiment n stub onto the PEC RS485 bus and to its ENABLE

using the DS16F95TX+ TXminus RXminusRX+ +5 GND ENB0 ENBn ENBz

+5

+5

Recieve

Transmit

SERIALENABLE

Vcc

R0998400RE

DEDI D

D

R

R

DS16F95

DS16F95

GND

GND

B

A

B

A

R0998400REDEDI

0 to 100 OHMS

Note the above NOR gate represents a NOR function

and does not necessarily specify the use of a NOR gate

SERIAL ENABLE is generated by experiment n upon valid

handshake with CIB after assertion of ENBn

NASA GRC flight electronics labStubbing in

Krasowski Rev 10182008 1 of 1

Vcc

middot middot middot

middot middot middot middot middot middot


NC

NC

Figure 3 Schematic diagramof the RS-485 bus interface provided to experiments byCommunications Interface Board (CIB) (image courtesyof NASA)


Exp 1 ENB

Exp 2 ENB

10 K Experiment 1

Experiment 2

Experiment nExp n ENB

CIB PEC

L W

10 K L W

10 K L W

10 volt

10 volt

10 volt

Figure 4 Schematic of the CIB enable lines for experimentsonboard the Passive Experiment Containers (PECs) Current limit-ing resistors as well as voltage limiting Zender diodes to protect CIBenable circuitry from experimental failure are shownwithin the CIB(image courtesy of NASA)

signal The systems are expected to be capable of accepting apacket from the CIB 250 milliseconds from the assertion ofthe enable and so boot-up must occur consistent with thisdelay Failure to receive this command and reply after 250msresults in the CIB disasserting the enable line and movingon to the next experiment This is of consequence to a sys-tem which uses the time between sequential acquisitions ofitself by the CIB to perform its tasks After completion of taskand data transfer with the CIB a system may turn itself offRemoval of power when not operating reduces some radia-tion total dose effects and can also remove the conditions forand thus clear a nondestructive latchup

Each transfer starts with a packet from theCIB containingthe experiments APID and so theoretically experiments donot need to consider the state of an enable line but merelylisten for their APID Given this fact and since the two com-munications busses are RS-485 links with proper wiring con-siderations over thirty experiments per RS-485 bus are poss-ible with a reprogrammed CIB

4 Software Description

The CIB firmware is built on a commercially available real-time kernel The firmware consists of serial inputoutputCCSDS packet building time keeping and MIL-STD-1553support modules in addition to top-level modules that man-age data handling and poll experiments

Data handling is straightforward Experimenters haveonly to implement a very simple protocol to enable communi-cation All packets have a fixed length Command packets are116 bytes long data packets are 1274 bytes long and acknowl-edgment packets are 10 bytes long [6] The CIB will queryexperiments one at a time Each query has the form in Box 1

The firmware packs experiment data into CCSDS packetsfor transmission and unpacks commands received from the

groundThis relieves developers from the task of implement-ing CCSDS packet handling

Experiments can be controlled through commands of upto 104 bytes in length No processing is done on commandsby the CIB they are simply passed to the experimentCommands may contain any kind of data including firmwareupdates Experiments are polled in round-robin fashion eachtransaction requiring roughly 25 seconds Experiments cantransmit up to 2MBday An experiment may receive a com-mand from the ground or transmit data during a singletransaction Data from the experiment is wrapped in aCCSDSpacket and buffered in theMIL-STD-1553 transceiver

MIL-STD-1553 transactions occur in frames The minorframes contain different transactions Amajor frame consistsof minor frames The major frames are repeated The ELCuses ten 100msminor frames for eachmajor frameThe resultis that data packets received from experiments are buffereda maximum of one second before being transmitted on theMIL-STD-1553 bus In addition to passing data the MIL-STD-1553module initializes the transceiver updates the timeand transmits the health and status packets of Table 1 once permajor frame

5 CIB Hardware

The core of the CIB is the 80C32E-5962-0051801QQC radi-ation tolerant 8 Bit ROMless microcontroller This performsall processing functions within the system The 80C32E hasthe following environmental operating specifications [7]temperature range is military (minus55∘C to 125∘C) no singleevent latch-up (SEL) below a linear energy transfer (LET)threshold of 80MeVmgcm2 and is tested up to a total doseof 30 krads (Si) according to MIL-STD-883 method 1019

Programmemory for the CIB is stored in the AT28C010-12DK-MQ-128Kx8 parallel EEPROM which is reprogram-mable in circuit at the bench but which is not reprogram-mable on-orbit The AT28C010 has the following environ-mental operating specifications [8] temperature range ismilitary (minus55∘C to 125∘C) no SEL below an LET threshold of80MeVmgcm2 and is tested up to a total cose of (accordingto MIL-STD-883 method 1019) 10 krad (Si) read-only modewhen biased and 30 krad (Si) read-onlymodewhen unbiased

Dynamic memory for the CIB is embodied in anM65608E-5962-8959818MZC radiation tolerant 128Kx8 verylow-power Complementary Metal Oxide SemiconductorStatic Random Access Memory (CMOS SRAM) TheM65608M has the following environmental operating spe-cifications [9] military temperature range is (minus55∘C to+125∘C) no SEL below a LET threshold of 80MeVmgcm2 125∘C and is tested up to a total dose of 30 krad (Si) accord-ing to MIL-STD-883 method 1019

MIL-STD-1553 communications are effected through theBU-63825D1-300 Space Advanced Communication Engine(SprsquoACE II) BCRTMT interface module The SprsquoACE II hasthe following environmental operating specifications [10]total gamma dose immunity of 1 times 106 Rad LET threshold of63MeVmgcm2 and a soft error rate of 256 times 10minus5 errorsdevice-day


ENBn for experiment 119899 is asserted

After 250 milliseconds the CIB will transmitSOP CRC Address Timestamp Packet Type Command or Padding

If the above packet is valid the experiment will transmitSOP CRC Address Timestamp Packet Type Data andor Padding

If the CIB receives a valid packet from the experiment the CIB will acknowledge the packetSOP CRC Address Timestamp Packet Type = ACK

Box 1

Table 1 Health and status packet format transmitted once per major frame (once per second)

Type Variable DescriptionUnsigned char opto[2] State of optoisolators that determine whether the AO and FTSCE experiments are enabledUnsigned long last poll time Beginning of the current polling cycleUnsigned short poll cycles Number of completed polling cyclesUnsigned char poll map[20] Determines which experiments are to be polledUnsigned short sequence[20] Packet sequence number of each of the experimentsUnsigned char valid crc[20] 0timesFF = validUnsigned long last cmd time[20] Time last experiment command receivedUnsigned long last cib cmd time Time last CIB command receivedUnsigned char valid ack[20] 0timesFF = validUnsigned short cmd cnt[20] Count of commands sent to experimentsUnsigned short cib cmd cnt Count of commands sent to CIBUnsigned short err cmd Command for nonpolled APID Error = APID 0timesFFFF = no errorUnsigned short err poll Invalid polling table received UnusedUnsigned char last cmd[106] Last command transmitted to experimentsUnsigned char last cib cmd[106] Last command transmitted to the CIBUnsigned char last ftsce cmd[100] Last command sent to FTSCEUnsigned char ftsce data[124] Data transmitted by FTSCEUnsigned char reserved[64]

The core components of the CIB hardware are listed inTable 2 along with their relevant environmental specifica-tions

MIL-STD-1553 coupling transformers and the two clockcrystals are screened for space applications All other activecomponents are deemed radiation hard to this missionthrough consultation with the customer A photograph ofthe CIB is given in Figure 5 The radiation environment inLEO consists primarily of trapped protons with some galacticcosmic rays and solar particles The expected and agreedto limit for total ionizing dose for the CIB was less than300 rad(si) per year (behind shielding) The CIB componen-try is accepted to be SEU tolerant and SEL hard to the ISSLEO radiation environment As such the CIB was designedfor long duration survival to the LEO radiation environment

6 Results

The Communications Interface Board or CIB embodies thefirst demonstration of a permanent communications andcontrol interface for deployable experiments to characterize

materials systems and components exposed to LEOTheCIBwas and is the core of two of the earliest science payloads onthe ELC affixed to the external structure of the ISS as part ofan Express Payload Adapter (ExPA) These two experimentsdeployed by astronauts during EVA are MISSE7 and -8MISSE7 was deployed had a successful mission and wassubsequently returned to Earth MISSE8 remains on orbit atthe time of this writing The CIB was delivered to the ISSon STS-129 in November 2009 along with MISSE7 Table 3lists experiments which use command and telemetry dataprovided by the CIB MISSE7 then returned when MISSE8was delivered in May 2011 with the CIB remaining aboard toprovide the simplified telemetry interface for MISSE8 Table4 listsMISSE8 experiments utilizing command and telemetrydata enabled by the CIB MISSE8 is scheduled for return inMarch 2014

The original intent for the CIB was to embody the com-munications component of a MISSE-specific infrastructurecapable of supporting two PECs with up to 20 separateexperiments with power uplink and downlink capabilitiesA PEC is a suitcase-like metal container which when opened


Table 2 CIB core system components and respective environmental operating specifications

Function Part number Temperature range Single event latchup (SEL)threshold Total radiation dose

Microcontroller 80C32E minus55∘C to 125∘C gt80MeVmgcm2 30 krad (Si)

Program memory AT28C010 minus55∘C to 125∘C gt80MeVmgcm2 10 krad (Si) under bias30 krad (Si) when unbiased

Dynamic memory M65608E minus55∘C to 125∘C gt80MeVmgcm2 30 krad (Si)MIL-STD-1553interface module BU-63825 Immune 1Mrad

Figure 5 Photograph of the flight Communications Interface Board(CIB) circuit board This image was taken prior to delivery duringfunctional testing of the circuit board and prior to the insertion ofthe flight MIL-STD-1553 transceiver (image courtesy of NASA)

and deployed presents two opposing experiment surfacesTwo PECs can thus provide zenith and nadir along with ramand wake presentations This infrastructure greatly reducesthe ISS interface complexity for future MISSE experimentsExperimenters would thus have a well-defined power andcommunication interface to the ISS to build to as well asan EVA compatible mechanical structure for deploying twoMISSE style PECs Further continuous monitoring of com-ponents and samples while on orbit removes the requirementof an experiment returning to Earth for postmission analysisAs such at end of mission experiments may be disposed ofvia deorbiting as will be the case for part of MISSE8

The decommissioning of the space shuttle brought withit a loss of EVA deployable experiments and as such thePEC structure is inconsistent with new requirements forrobotic deployment of science payloads and environmentalsensors for insertion onto the ELCs However the CIB argu-ably represents a communication and control interface for asystem consistent with current specifications

While the CIB hardware currently residing on ELC2onboard the ISS may not be utilized after the completionof MISSE8 it should be recognized that the architecture issuitable for future use in vehicle health monitoring applica-tions The current hardware design has been proven to behighly reliable in the demanding space flight environmentThe simple telemetry interface provided by the CIB enabled

the experiments listed in Table 3 on MISSE7 and Table 4 onMISSE8 respectively Broad applications enabled by the CIBshould be noted from processor testing to solar cell healthmonitoring and fromCMOS image sensor testing to a varietyof materials testing Two individual experiments specificallyrelated to vehicle health monitoring will be discussed in thenext section

7 Health Monitoring Enabled by the CIB

71 SiC JFET Health Monitoring Experiment An example ofa health monitoring circuit flown on MISSE7 was the siliconcarbide (SiC) Junction Field Effect Transistor (JFET) Experi-ment designed by the NASAGRCmobile and remote sensinglaboratory and SiC development group NASA GRC has along history in extreme temperature range silicon carbideelectronics and packaging development having demonstratedSiC logic circuits operating over a temperature range ofminus125∘C to 500∘C [11] Current long duration extreme tem-perature testing is performed in laboratory ovens and coldchambers but future use is anticipated onflight vehicles In aneffort to demonstrate the technology in a flight environmenta health monitoring experiment was designed for SiC JFETsin high temperature packaging which was the first spaceflight of this technologyThe experiment consisted of two SiCJFETs one in room temperature commercial packaging theother in high temperature packaging developed by the OhioAerospace Institute and NASA GRC [12]

The experiment monitors the current versus voltagetransfer characteristics or a curve trace of both transistorsduring the flightThe transfer characteristics of the transistorsshow any electrical or physical degradation of the transistorswhich is the primary concern of this experiment demon-stration This transfer characteristics are generated with amicrocontroller-based curve tracing circuit The CIB RS-485protocol includes a timestamp in each transaction whichthe SiC JFET uses to determine when to initiate a curvetrace Tominimize bandwidth used the SiC JFET experimentwill only run once every hour When the CIB queries thisexperiment if the timestamp does not lie in the first tenminutes of the hour the experiment will power itself downto wait for the next query In addition to using the CIB enableline as a safety to lockout transmission on the RS-485 bus thisexperiment uses the enable line as a signal to a latch to enablepowering upThe CIB assertion of the enable line powers theexperiment up after which the experiment listens for the CIBcommand packet The experiment receives the timestamp


Table 3 Materials on the International Space Station Experiment Seven (MISSE7) flown on ISS from November 2009 to May 2011

Short experiment name APID Experiment description Provider

MCPE 1300 Multicore processor single event upsettesting

Naval ResearchLaboratory

GRC experiment set 1301 SiC transistor health testing [12] H2sensor and zenithnadir AO monitor NASA GRC

SEUXSE 1302 Xilinx FPGA SEU Testing Sandia NationalLaboratory

Not used 1303Not used 1304CIE 1305 CMOS imager experiment Assurance technology

FTSCE II 1306 Solar cell health monitoring [14ndash18] NRL NASA GRC andAFRL

Boeing ram side experiment 1307 Materials testing Boeing

HyperX 1308 High performance low-powerprocessor SEU testing [19] NASA GSFC

SpaceCube ldquoArdquo 1309 Advanced processor design SEUtesting [20 21] NASA GSFC

SpaceCube ldquoBrdquo 1310 Advanced processor design SEUtesting [20 21] NASA GSFC

Wake AO fluence monitor 1311Wake atomic oxygen fluencemonitorthermal control paintsExperiment

NASA GRC

Boeing wake side experiment 1312 Materials testing Boeing

AFRL wake 1 1313 Tribology measurements AFRL Dayton U ofFlorida


AFRL ram 1 1315 Tribology measurements AFRL Dayton U ofFlorida


iMESA 1317 Miniaturized electrostatic analyzer[22] US Air Force Academy

LTESE 1318 Lead-free technology experiment inspace environment MSFC

Ames 1319 Thermal protection systems sensors NASA ARC NASA LaRCNASA JSC and Boeing

Boeing PICA 1320 Materials testing BoeingRam atomic oxygen fluencemonitorthermal controlpaints experiment

1321 NASA GRC

determines if the time is within the ten-minute window andthen either proceeds with curve tracing or goes to sleep

Figure 6 shows experiment data in the form of curvetraces frommidflight monitoring of the SiC transistor healthBoth the room (Figure 6(a)) and high temperature (Figure6(b)) packaged transistor test data are shown The graphoverlays preflight curves with those 6 months into the flightThese midflight results show no degradation of transistorperformance during the 6-month period [12]

The experiment board shown in Figure 7 resided at APID1301 as shown in Table 3 In addition to the SiC JFETexperiment the circuit board and electronics set also sup-ported two additional experiments theMakel Gas Sensor and

the atomic oxygen fluence monitor neither of these will bediscussedThe design of the CIB enablesmany types of healthmonitoring to be performed with the sample rate being thelimiting factor

72 Forward Technology Solar Cell Experiment II Anotherexperiment toward vehicle health monitoring enabled by theCIB is the Forward Technology Solar Cell Experiment II(FTSCE II) The experiment was designed by the U S NavalResearch Laboratory with instrumentation development bythe NASA GRC MaRS Lab This experiment monitoredsolar cell health by measuring current versus voltage (I-V)curve characteristics Space vehicles in Earth orbit rely on


Table 4 Materials on the International Space Station Experiment Eight (MISSE8) flown on ISS fromMay 2011 to present (April 2013)

Short experimentname APID Experiment description Provider

None 1300

Reflectarray 1301 Characterize performance of components ofa flexible phased array antenna NASA GRC

SEUXSE 1302 Xilinx FPGA SEU testing Sandia National LabNot used 1303Not used 1304

PASCAL 1305 Primary arcing effects on solar cells at LEOLockheed Martin JAXA

Kyushu Institute ofTechnology

FTSCE III 1306 Solar cell health monitoring [23ndash25] NRL NASA GRC and AFRLNot used 1307

HyperX 1308 High performance low-power processorSEU testing [19] NASA GSFC

SpaceCube ldquoArdquo 1309 Advanced processor design SEU testing NASA GSFCSpaceCube ldquoBrdquo 1310 Advanced processor design SEU testing NASA GSFC

08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K

Drain voltage VD (V)

Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)

Figure 6 Current versus voltage transfer curves for given gate voltages of the two flight silicon carbide (SiC) Junction Field Effect Transistors(JFETs) (a) shows characteristics for room temperature packaged JFETs for preflight and after over six months of flight (b) shows thecharacteristics for the high temperature packaged SiC JFET (image courtesy of NASA)

photovoltaic or solar cells as their power source Space envi-ronment effects can degrade photovoltaic cell performanceproviding less power to the vehicle and thus affecting thehealth and operating envelope of the space vehicle Whiletechnology can be used tomitigate the degradation the spacevehicle designer and operator should know how the systemwill degrade and respond to the changing power systemoutput

Photovoltaic cells have current versus voltage character-istic which can provide insight into the health of the cellFigure 8 shows an example of a solar cell I-V curve frominitial FTSCE II on-orbit data Performance degradation ofthe cell will show up as less current output shifting thecurve in Figure 8 downward along the vertical axis as the celldegrades FTSCE II is comprised of 36 experimental solarcells as shown in Figure 9 along with measurement circuitry


Figure 7 Silicon carbide junction field effect transistor (SiC JFET)health monitoring flight experiment circuit board (image courtesyof NASA)

045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps

FTSCE II sun angle 5∘ temperature 52∘C

sim

Figure 8 Typical I-V (current versus voltage) curve for a solar cellas measured by the Forward Technology Solar Cell Experiment II(FTSCE II)

to provide I-V curve data alongwith environment parametersof temperature and sun position in relation to the solar cellsThe measurement hardware of FTSCE II flown on MISSE7is actually a reflight of the same hardware originally designedfor and flown as FTSCE I onMISSE 5 [13] FTSCE II resided atthe APID 1306 and would transmit data packets consisting ofI-V curve data alongwith relevant environmental parametersFuture results covering the complete FTSCE II experimentare expected while selected results from in flight data arepresented in [14ndash17]

8 Future Health Monitoring Applications

The CIB design discussed in this paper is one possiblehardware implementation of the architectureThis designwasfocused on providing reliable operation within a radiationenvironment So the hardware implementation describedrepresents a design to achieve this goal The architecture of

Figure 9 Sun looking face of the Passive Experiment Container(PEC) containing passive material samples and cells as flown onMaterials International Space Station Experiment 7 (MISSE7) Solarcells can be denoted by the wires to attach to the measurementcircuitry of the Forward Technology Solar Cell Experiment II(FTSCE II) (image courtesy of NASA)

the CIB may also be realized with a different hardware setto suit other needs For instance in a more benign environ-ment the choices for suitable hardware increase significantlyand the design could also be shrunk physically The hard-ware could be implemented in a variety of processing plat-forms which might even include theMIL-STD-1553 interfaceonboard One likely hardware target for the CIB architectureis a field programmable gate array (FPGA) This reconfigur-able platform would allow the processing unit and commu-nication to exist in single IC greatly shrinking the physicalfootprint of the circuitry A smaller CIB would providegreater access to additional flight platforms

Another consideration for future use is the reliability ofthe sensors and instruments which utilize the RS-485 bus Asthe sensors mature and are demonstrated to be more reliablein operation the enable lines provided by the CIB might notbe needed This elimination would reduce the wiring neededas well as the physical size of the CIB

Hardware changes are not the only possible architecturemodifications which would lead to expanded use Softwarealterations may also be applied to allow increased use ofthe architecture For instance current CIB protocol mightbe expanded The CIB operated with a commandresponseprotocol where the CIB controlled the RS-485 bus in muchthe same way as the bus controller in the MIL-STD-1553 busOne feature possible on a commandresponse bus is nodeto node communication Because the CIB uses packet-basedtransfers the software protocol could be expanded to includethese node to node transfers whereby a request for node tonode transfer is communicated to the bus controller whichis then granted by the CIB through an additional messageEven in the current configuration node to node transfer ispossible since a node needs only to actively listen to the busfor messages encoded in its packet

Future use of this architecture may be a vehicle healthmonitoring bus included in aircraftspacecraft electronicsystems The CIB or future hardware could be the interfacebetween all health monitoring sensors and the crafts centralcontrol unit Used in this manner the CIB could providethe craft with vehicle health information through a singleinterface such as the MIL-STD-1553 bus


9 Conclusion

This paper demonstrates that the CIB is an improved archi-tecture enabling simple vehicle health monitoring on the ISSWhile the ISS has in place a communications architecturewhich enables health monitoring telemetry and control theCIB improves and adds to this infrastructure by providing asimpler interface This is accomplished by interfacing withthe ISS MIL-STD-1553 bus and providing two multidropRS-485 busses for experiments sensors and health mon-itoring systems to communicate on The RS-485 bussesmake available the MIL-STD-1553 telemetry command andcontrol services without the complex development requiredfor MIL-STD-1553 This simpler interface enables sensor andinstrumentation development for vehicle health monitoringapplications

The CIB provides this simpler communication interfacewhile maintaining the reliability expected of a space flightsystem on the ISS The CIB was developed with radiationtolerance and reliability as the primary design considerationsWith over three years of successful operation on the ISS overtwo missions the CIB has proven to be highly reliable andtolerant to the LEO radiation environment while provid-ing simpler vehicle health monitoring communication sup-port

The CIB also enabled future materials and device devel-opment which lead to further use in health monitoringsystemsThis paper gave two examples of a healthmonitoringexperiment flown on the external of the ISS for over a yearThe SiC JFET is a high temperature component which hasuses throughout a vehicle to include health monitoring inextremely hot environments The flight on MISSE7 was thefirst space flight of this technology andwas only possible withthe simple telemetry interface provided by the CIB FTSCEII demonstrated solar cell health monitoring on the ISS withreal-time telemetry enabled by the CIB

The CIB design discussed is one implementation of thearchitecture This architecture might be expanded on orimplemented differently for a different platform Anotherprocessing technologymight be utilized in the architecture ina more benign environment such as an aircraft Future soft-ware development may use the CIB protocol to support nodeto node transfer allowing sensor fusion techniques for vehiclehealth monitoring

Acknowledgments

The authors would like to acknowledge George Y Baaklinibranch chief of theOptical Instrumentation andNDEBranchat the NASA Glenn Research Center and Robert Walters ofthe Naval Research Laboratory for support of this work Thiswork was funded by the U S Naval Research Laboratory

References

[1] ldquoSpace station ionizing radiation design environmentrdquo TechRep NASA SSP-30512 Revision C June 1994

[2] ldquoInternational standard payload rack to international spacestation software interface control document part 1rdquo Tech RepNASA SSP 52050 Revision G 2007

[3] ldquoAircraft internal time division commandresponse multiplexdata busrdquo Tech Rep US Department of Defense MIL-STD-1553B 1996

[4] ldquoEXPRESS Logistics Carrier (ELC) development specificationrdquoTech Rep NASA SSP-52055 Revision C 2006

[5] P P Jenkins R JWaltersM J Krasowski et al ldquoMISSE7 Build-ing a permanent environmental testbed for the internationalspace stationrdquo in Proceedings of the 9th International Conferenceon Protection of Materials and Structures From Space Environ-ment (ICPMSE rsquo08) vol 1087 pp 273ndash276 May 2008

[6] ldquoCommunications interface board serial interface specifica-tionrdquo Tech Rep NASANRL ICDDocument Revision 9 2009

[7] Atmel Corporation ldquoRad Tolerant 8-bit ROMless Microcon-troller 80C32E Datasheetrdquo 2007

[8] Atmel Corporation ldquoSpace 1-MBit (128K x 8) Paged ParallelEEPROMs AT28C010-12DK Datasheetrdquo 2011

[9] Atmel Corporation ldquoRad Tolerant 128K x 8 5-Volt Very LowPower CMOS SRAMM65608E Datasheetrdquo 2008

[10] Data Device Corporation ldquoBU-63285 Space Level MIL-STD-1553 BCRTMT Advanced Communication Engine (SPrsquoACEII) Terminal Datasheetrdquo 2005

[11] P G Neudeck M J Krasowski L-Y Chen and N F ProkopldquoCharacterization of 6H-SiC JFET integrated circuits over abroad temperature range from minus150∘C to +500∘Crdquo MaterialsScience Forum vol 645ndash648 pp 1135ndash1138 2010

[12] P G Neudeck N F Prokop L C Greer III L-Y Chen andM J Krasowski ldquoLow earth orbit space environment testing ofextreme temperature 6H-SiC JFETs on the international spacestationrdquo Materials Science Forum vol 679-680 pp 579ndash5822011

[13] M J Krasowski L C Greer J M Flatico P P Jenkins andD C Spina ldquoBig science small-budget space experiment pack-age aka MISSE-5 a hardware and software perspectiverdquo in Pro-ceedings of the 19th Space Photovoltaic Research and TechnologyConference September 2005

[14] P P Jenkins R J Walters M Gonzalez et al ldquoInitial resultsfrom the second forward technology solar cell experimentrdquo inProceedings of the 35th IEEE Photovoltaic Specialists Conference(PVSC rsquo10) pp 1124ndash1127 June 2010

[15] K M Edmondson A Howard P Hausgen et al ldquoInitial on-orbit performance analysis of Inverted Metamorphic (IMM3J)solar cells on MISSE-7rdquo in Proceedings of the 37th IEEE Pho-tovoltaic Specialists Conference (PVSC rsquo11) pp 3719ndash3723 June2011

[16] T Stern and A Reid ldquoModular solar panels using componentsengineered for producibilityrdquo in Proceedings of the 37th IEEEPhotovoltaic Specialists Conference (PVSC rsquo11) pp 1626ndash1629June 2011

[17] ADHowardDMWilt P P Jenkins KMTrautz PHausgenand J M Merrill ldquoSelected on-orbit data from the FTSCE IIaboard the MISSE 7 testbedrdquo in Proceedings of the 38th IEEEPhotovoltaic Specialists Conference (PVSC rsquo12) pp 3275ndash3280June 2012

[18] T D Sahlstrom P E Hausgen J Guerrero A D Howard andN A Snyder ldquoUltraviolet degradation testing of space protect-ive coatings for photovoltaic cellsrdquo in Proceedings of the 33rdIEEE Photovoltaic Specialists Conference pp 1ndash5 May 2008

[19] A S Keys J H Adams R E Ray M A Johnson and J DCressler ldquoAdvanced avionics and processor systems for spaceand lunar explorationrdquo in AIAA Space 2009 Conference andExposition Anaheim Calif USA September 2009 AIAA 2010-8783


[20] D Petrick ldquoSpaceCube current missions and ongoing platformadvancementsrdquo The MAPLD Workshop 2009 httpsneppnasagovmapld 2009

[21] K M Zick C-C Yu J P Walters and M French ldquoSilent datacorruption and embedded processing with NASArsquos spacecuberdquoIEEE Embedded Systems Letters vol 4 no 2 pp 33ndash36 2012

[22] R Balthazor M G McHarg C L Enloe et al ldquoSensitivityof ionospheric specifications to in situ plasma density obser-vations obtained from electrostatic analyzers onboard of aconstellation of small satellitesrdquo inProceedings of the AIAAUSUConference on Small Satellites SSC12-IV-1 Logan Utah USA2012

[23] B Cho R Lutz J Pappan et al ldquoIMM experimentation inthe next frontier Emcorersquos participation in the MISSE-8 pro-gramrdquo in Proceedings of the 35th IEEE Photovoltaic SpecialistsConference (PVSC rsquo10) pp 110ndash112 June 2010

[24] T D Sahlstrom P E Hausgen D M Wilt A D Howard MD Anderson Jr and N A Snyder ldquoSpace flight experimentadvanced solar cells and protective materials on the ISS exte-riorrdquo in Proceedings of the 35th IEEE Photovoltaic SpecialistsConference (PVSC rsquo10) pp 2610ndash2615 June 2010

[25] S Gasner M Tresemer S Billets D Bhatt and P WallisldquoDesign amp fabrication of the lockheed martin solar cell demon-stration experiment for the ISS Forward Technology Solar CellExperiment IIrdquo in Proceedings of the 34th IEEE PhotovoltaicSpecialists Conference (PVSC rsquo09) pp 791ndash793 June 2009

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



permanent loss of a circuit component With this in mindcare must be taken in the design of any electronic systemexpected to operate reliably on the ISS for extended period oftime and be tolerant of the expected radiation environment

To support science payloads the ISS as a facility providesthree telemetry communications interfaces [2] for residentexperiments with its associated physical layerprotocol lowrate data link MIL-STD-1553 medium rate data link Ether-net and high rate data link fiber optic Each interface canprovide telemetry to the ground Increased bandwidth comeswith increased cost in development tomeet the physical inter-face requirements The only interface available throughoutthe ISS is the MIL-STD-1553 bus In addition to telemetrydata the Mil-STD-1553 bus performs the command healthand status data transferThis is done for safety reasons so thathealth and status data are transmitted on the most reliablecommunication bus

The MIL-STD-1553 [3] ldquoAircraft Internal Time DivisionCommandResponse Multiplex Data Busrdquo defines a physicallayer as well as a bus protocol The MIL-STD-1553 bus ishighly reliable and robust in that it is a deterministic com-mand and response protocol The ISS adds additional layersto those of the MIL-STD-1553 standard in effect makingthe ISS MIL-STD-1553 implementation a superset of themilitary standardWhich allows ISSMIL-STD-1553 hardwareto interface with other space and aircraft platforms but notnecessarily the converse The MIL-STD-1553 bus is deployedon numerous U Smilitary aircrafts including the F-16 FalconFA-18 Hornet AH-64 Apache and P-3C Orion and hasalso been adopted by North Atlantic Treaty Organization(NATO)TheMIL-STD-1553 bus transmits data at 1Mbitsec-ond The command and response protocol of the bus addsoverhead reducing the effective bit rate for data transfer Inaddition the ISS adds overhead to the bus transfers Onelayer added by ISS to theMIL-STD-1553 telemetry is the Con-sultative Committee for Space Data Systems (CCSDS) head-ers which allow for data telemetry routing in space Eachnode in the telemetry system is provided with a unique appli-cation identifier (APID) which is part of the CCSDS headerto enable routingThese APIDs allow a user on the ground toreceive telemetry and command their node from anywherewith internet connectivity The ISS allots 128 kBytes of tele-metry data per second some of which is used for overheadThe ISS allows commands from the ground to be routed toAPIDs residing on the MIL-STD-1553 bus

Onboard the ISS there is an Express Logistics Carrier(ELC) facility which is primarily designed to store ISSreplacement parts but also has two science payload slots perplatform [4] Each science payload site has 28V and 120Vpower available A MIL-STD-1553 communications repeater(bus controller) link to the ISS is also provided by the ELCallowing telemetry data to pass through

The CIB was needed to be the communications backbonefor a permanent testbed on the ELC of the ISS which wouldutilize the ISS telemetry of the MIL-STD-1553 bus TheCIB needed to provide simpler communication interface toexperimenters while maintaining the reliability expected ofa space flight system on the ISS The CIB needed to bedesigned with radiation tolerance and reliability as primary

considerations The CIB was designed by the NASA GlennResearch Center (GRC) Mobile and Remote Sensing (MaRS)Laboratory The first experiment set to utilize the testbedwas the Materials on the International Space Station Seven(MISSE7) [5] MISSE7 was comprised of numerous passiveexperiments and over 21 active experiments using the com-mand and telemetry capabilities provided by theCIBMISSE7used two Extra-Vehicle Activity (EVA) deployable suitcase-like containers called a Passive Experiment Container (PEC)in which numerous experiments are contained These PECsare carried by astronauts opened and mounted on the ELCWhen the experiment was completed an additional EVAwasused to retrieve the PECs and install a new one for the follow-on experiment setMISSE8This exchange required a physicalcommunications link which was swappable The need foron-orbit exchange of PECs required a physical communi-cations link robust enough to withstand potential damageencountered during the swap

The CIB was installed during Space TransportationSystem-129 (STS-129) and is currently flying on the exteriorof the International Space Station mounted on the ExpressLogistics Carrier 2 (ELC-2) The CIB provides a simple RS-485-based communications interface between experimentsinstruments or sensor systems and the ELCrsquos MIL-STD-1553bus This allows developers to design on simple platformswithout having to confront the difficulty of integrating theirexperiments directly into the ELC or the ISS The CIBcurrently provides serial communication supporting twentyactive systems Figure 1 shows the CIB within the MISSE7communication architecture including the interface to theISS telemetry through the ELC Follow-on experiments(MISSE8) leave the CIB in place and swap out one or bothof the allowed PECs

This paper will discuss in detail the technical devel-opment and design of the CIB hardware and architectureRecent results from current operations aboard the ISS will beprovided Specific experiments supported by the CIB like aSilicon Carbide Junction Field Effect Transistor (SiC JFET)health monitoring and a solar cell health monitoring will bediscussed Future health monitoring applications to includenode to node schemes will also be briefly discussed

2 CIB Design

The CIB is designed to be a highly reliable and radiationhard communications bridge from the ISSELC MIL-STD-1553 to onboard experiments sensors and health monitoringsystems The CIB is constructed from components designedor known to be radiation tolerant of LEO conditions for over20 years of operation Further the CIB is designed to be toler-ant of the electrostatic discharge (ESD) anticipated to occurduring removal and insertion of new payload systems overmultiple missions

Communications over each RS-485 bus was limited to9600 baud which is 9600 bits of data per second for eightbit words Though theoretically capable of at least ten timesthis bandwidth the CIBwas designed for 9600 baud as a con-sequence of some experiments in MISSE7 being only capableof that rate due to hardware or software constraints Thus



Downlinktelemetry


InternationalSpace

Station(ISS)


(CIB)RS-485 bus




Experiment n
















Glue logic54ACXX

Data ADDR

ADDR

ADDR

DataCTRL

CTRL

CTRL

TXRXUA

RT80

C32E

-30

mic

roco

ntro

ller

IO p

orts

Dec

ode

Dec

ode

AT28

C010

EEP

ROM

ENB0

ENBn

ENB0

ENBn

Common



RCV+RCVminus

XMIT+

XMITminus

Shield


DS16F95

DS16F95

Dual1of2

MUXSelect

Bankselect

INSTRPEC

CIB

M65

608E

128

Ktimes8

SRA

M

D

D





+5

+5

Recieve

Transmit

SERIALENABLE

Vcc

R0998400RE

DEDI D

D

R

R

DS16F95

DS16F95

GND

GND

B

A

B

A

R0998400REDEDI

0 to 100 OHMS







Vcc




NC

NC



Exp 1 ENB

Exp 2 ENB

10 K Experiment 1

Experiment 2


CIB PEC

L W

10 K L W

10 K L W

10 volt

10 volt

10 volt











5 CIB Hardware










Box 1





6 Results
































NASA GRC










1321 NASA GRC









None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Downlinktelemetry


InternationalSpace

Station(ISS)


(CIB)RS-485 bus




Experiment n
















Glue logic54ACXX

Data ADDR

ADDR

ADDR

DataCTRL

CTRL

CTRL

TXRXUA

RT80

C32E

-30

mic

roco

ntro

ller

IO p

orts

Dec

ode

Dec

ode

AT28

C010

EEP

ROM

ENB0

ENBn

ENB0

ENBn

Common



RCV+RCVminus

XMIT+

XMITminus

Shield


DS16F95

DS16F95

Dual1of2

MUXSelect

Bankselect

INSTRPEC

CIB

M65

608E

128

Ktimes8

SRA

M

D

D





+5

+5

Recieve

Transmit

SERIALENABLE

Vcc

R0998400RE

DEDI D

D

R

R

DS16F95

DS16F95

GND

GND

B

A

B

A

R0998400REDEDI

0 to 100 OHMS







Vcc




NC

NC



Exp 1 ENB

Exp 2 ENB

10 K Experiment 1

Experiment 2


CIB PEC

L W

10 K L W

10 K L W

10 volt

10 volt

10 volt











5 CIB Hardware










Box 1





6 Results
































NASA GRC










1321 NASA GRC









None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Glue logic54ACXX

Data ADDR

ADDR

ADDR

DataCTRL

CTRL

CTRL

TXRXUA

RT80

C32E

-30

mic

roco

ntro

ller

IO p

orts

Dec

ode

Dec

ode

AT28

C010

EEP

ROM

ENB0

ENBn

ENB0

ENBn

Common



RCV+RCVminus

XMIT+

XMITminus

Shield


DS16F95

DS16F95

Dual1of2

MUXSelect

Bankselect

INSTRPEC

CIB

M65

608E

128

Ktimes8

SRA

M

D

D





+5

+5

Recieve

Transmit

SERIALENABLE

Vcc

R0998400RE

DEDI D

D

R

R

DS16F95

DS16F95

GND

GND

B

A

B

A

R0998400REDEDI

0 to 100 OHMS







Vcc




NC

NC



Exp 1 ENB

Exp 2 ENB

10 K Experiment 1

Experiment 2


CIB PEC

L W

10 K L W

10 K L W

10 volt

10 volt

10 volt











5 CIB Hardware










Box 1





6 Results
































NASA GRC










1321 NASA GRC









None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Exp 1 ENB

Exp 2 ENB

10 K Experiment 1

Experiment 2


CIB PEC

L W

10 K L W

10 K L W

10 volt

10 volt

10 volt











5 CIB Hardware










Box 1





6 Results
































NASA GRC










1321 NASA GRC









None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














Box 1





6 Results
































NASA GRC










1321 NASA GRC









None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation





































NASA GRC










1321 NASA GRC









None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












None 1300








08

06

04

02

000 5 10 15

0 h4304 h

TO-8 40 120583m10120583m JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 Vminus5 V

minus4 V

minus3 V

minus2 V

minus1 V

0 V

VG

(V)

(a)

08

06

04

02

000 5 10 15

0 h4304 h

40 120583m10120583m HT-JFET T = 296K


Dra

in cu

rren

tID

(mA

)

minus8 V

minus6 V

minus10 V

minus4 V

minus2 V

minus1 V

0 V

VG

(V)

(b)






045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











045

04

035

03

025

02

015

01

005

00 05 1 15 2 25

Volts

Am

ps


sim











9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










9 Conclusion





Acknowledgments


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation


















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Research Article CIB: An Improved Communication...

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