NASA Technical Memorandum 83433

NASA-TM-83433 19830026614

, Design of a Microprocessor-Based Control,Interface and Monitoring (CIM) Unit forTurbine Engine Controls Research

John C. DeLaat and James F. SoederLewis Research CenterCleveland, Ohio

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' June 1983LANGLEY RESEAR_:_ _Z_INT_.R

LIBRARY, NASAHAMPTON, VIRGINIA

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controls computer, necessary 1ntertace hardware and a system to monitor

DESIGNOF A MICROPROCESSOR-BASEDCONTROL,INTERFACE,ANDMONITORING(CIM) UNIT FORTUR81NEENGINECONTROLSRESEARCH

John C. DeLaat and James F. Soeder

National Aeronautics and Space AdministrationLewis Research Center

Cleveland, Ohio 44135

SUMMARY

Hl_h speed minicomputers have been used in the past to implement advanceddigital control algorithms for turbine engines. These minicomputers are typi-cally large and expensive. It is desirable for a number of reasons to usemicroprocessor-based systems for future controls research. They are relativelycompact, inexpensive, and are representative of the hardware that would be used

_ for actual engine-mounted controls. The Control, Interface, and Monitoring_ Unit (CIM) contains a microprocessor-based controls computer, necessary inter-' tace hardware and a system to monitor the control while it is running an

engine. It is presently being used to evaluate an advanced turbofan enginecontrol algorithm.

INTRODUCTION

In recent years, advanced turbine engine control algorithms have beensuccessfully implemented on high speed minicomputers (refs. i to 3). However,there is a distinct disadvantage to this approach. Minicomputers typicallyoccupy several large cabinets (fig. 1). In addition, the minicomputer shownrequlred interface hardware occupying a doub]e 19 inch relay rack (fig. i)(ref. 4). Ubvious]y, actual engine contro]s would not be implemented on aprocessor this size. So, to lend credibility to future research, hardwareslmllar to that which wou]d be used by manufacturers of engines and controlsis desired. Off-the-she]f 16-bit microprocessors are now available which arecapable of executing advanced contro] software in real-time. Because of theirsmall size and low cost, these microprocessors could then make research indistributed contro]s and multiprocessin9 feasible at a reasonab]e cost. Tnus,it would be desirable to verify that implementin 9 advanced control algorithmson one of these processors is indeed possible.

Several features are necessary in the system on which this research is tobe carried out. First, the hardware must be portab]e so that it can be movedto either a simulation faci]ity or an engine test facility as needed. Second,

• since this is a research environment, one must be able to interrogate the con-trol wni]e it is running to verify that it is indeed doing what it is supposedto. Lastly, the unit should have the flexibility to adapt to future app]ica-tions so that new hardware does not have to be fabricated for each new researchundertakin 9 that arises.

The Control, Interface, and Monitoring (ClM) Unit has been designed tomeet these needs. An overall description of the unit, along with detaileddesign information are presented in this report. A typical user session ispresented in the appendix.

OVERALLDESCRIPTION

The CIM unit consists of two major functional blocks (fig. 2), housed in adouble relay rack (fig. 3). The first functional block is the MicrocomputerControl. It consists of a commercially available single board computer,input/output boards which interface to the single board computer, and a pairof floppy disk drives and their controller board. The circuit boards aremounted in a standard-width chassis which also contains the necessary powersupplies.

The Intel 8086 was chosen for the processor on which to base the micro-computer control unit. It was a readily available 16 bit processor and wasfelt to have the speed necessary to execute advanced turbine engine controlalgorithms. Also, it supported an arithmetic co-processor which could even-tually allow controls to be implemented using floating point arithmetic.

The second major functional block of the CIM unit is the Interface andMonitoring Module (fig. 2}. The interface portion of this module consists ofthree elements. Connectors in the base of the CIM unit bring signals in andout of the unit. A patch panel is used to correlate signals from outside theCIM unit with signals inside the CIM unit. Lastly, buffer amplifiers are pro-vided in case any of these signals should require buffering. These elementsand how they relate to the rest of the ClM unit are shown in figure 4. Alsoshown in fi9ure 4 are the functional elements used for monitoring. If anoperational control were being designed, the control and its interface hard-ware would be sufficient. However, since the CIM unit is being used in aresearch environment, it is necessary to be able to interrogate the controlwhile it is running to determine if it is operating correctly. The monitoringsystem provides this capability. Any signal in the ClM unit can be selectedat the front panel by the user. This signal is then displayed in either voltsor engineering units, whichever is more meaningful to the user.

To accomplish the monitoring function, all the I/0 signals to and from theCIM unit are fed to a many input, single output multiplexer. This multiplexerthen selects the desired channel and outputs it to a scaling circuit which canscale the signal so that it looks like either volts or engineering units. Theuser selects the desired readout with a switch on the front panel. The outputof the scaling circuit is then displayed on a digital volt meter (DVM) on theCIM unit front panel. An alphanumeric display is provided to inform the userwhat units are bein 9 displayed on the DVM.

A microcomputer is used to control all the monitoring functions. A singleboard system was custom-designed for this purpose. It incorporates an Intel8085 and the necessary peripherals and memory. The 8085 was chosen because offamiliarity with the processor and because Intel development hardware andsoftware had already been acquired to support the 8086 used for the controlmicrocomputer. Also, the performance required for the monitoring system didnot warrant the increased hardware complexity of a system designed around the8086 microprocessor. The 8085 microcomputer, then, provides an intelligentmonitoring system which in turn provides through software, the flexibility toadd features as well as modify and enhance existing ones.

Finally, fiyure 4 shows the switches and indicator lights which are alsopart of tile monitoring system. These are located on the CIM unit display panel(rig. 3). Their inputs and outputs are available at the patch panel so that_heir tunction can be defined by the user. Potential applications for theseinclude mode switches and status lights for the control microcomputer.

All the electronics for the monitoring system are contained in two rack-mountable chassis. The analoy electronics are in one chassis and the digitalelectronics in the other. These chassis are isolated to prevent coupling ofdigital noise into the analog signals which are being monitored. They are theLwo chassis shown in the right side of figure 3.

DETAILED SYSTEMDESCRIPTION

Controls Hardware

As mentioned earlier, the control microcomputer is based on the Intel 8086.An oil-the shelf, single board computer, the iSBC 86112A is used (fig. 5).This is a printed circuit board containing a 5 Mhz 8086 as its central proc-essing unit (CPU). In addition the board contains 32 kilobytes of dynamicrandom access memory (RAM), 32 kilobytes of expansion RAM, and 32 kilobytes oferasable, programmable read only memory (EPROM). The board also has 24parallel input/output lines, a serial input/output port, and 2 proyrammablecounter/timers. The board can accept an 8087 (iSBC 337) numerlcs coprocessorwhich gives the 8086 the ability to handle floating-point arithmetic. This isvery useful for converting scaled integers, which the control uses, intoenyineering units which are easily readable by the user. Lastly, the 86/12Ais Multibus compatible. The Multibus/IEEE 796 is a standard microprocessorbackplane interface bus originally developed by Intel. There is a mu]titudeof boards from a variety of vendors compatible with this bus. This allows theuser to select as off-the-shelf just about whatever support boards arerequired.

Tlle iSBC 86112A is mounted in a chassis which contains the Multibus inter-

face and the necessary power supplies. This chassis has slots for eightMultlbus compatible circuit boards and is shown in figure 6. The iSBC 86112Auses one of these eight slots. Six of the remaining seven slots in the chassisare used in the present configuration shown in figure 7. The first slot belowthe processor card contains the floppy disk controller. This board provideson-line floppy disk support and allows the use of a disk operating system inconjunction with tlle control hardware and software. The controller used, sup-ports up to four drives and can read and write either single or double densitydisks. Presently, two double density drives are being supported by this onecontroller board.

Three boards are used for analog I/0. Two are analog output boards andthe third is an ana]og input board. Both analog output boards use 12-bitdigital to analog converters (DAC's). One board contains eight DAC's and theother contains four DAC's for a total of twelve DAC's altogether. The ana loyinput board, can support up to 32 differential inputs. These inputs aremultiplexed to a single 12-bit, analog to digital converter.

There are two boards which support discrete I/0. The flrst supports 24discrete contact closure inputs. The second has 32 contact closure (relayclosure) outputs. The disk controller and all of the I/0 boards are con-trolled through the Multibus by the 8086 processor.

Controls Software

The controls hardware runs under the control of a commercially availabledisk operating system, CP/M-86, which occupies about 12 kilobytes of the 64kilobytes of RAMavailable on the 86/12A board. This operating system loadsprograms and data from disk into processor memory and manipulates programs anddata on the disks. User programs can also make use of CP/M-86 facilities.One program which makes use of these facilities is the Microprocessor Inter-active Data System (MINDS) developed at NASALewis. This software is used toextract data from the control while it is running. MINDScan examine variableswhich are internal to the control software. It pulls these values directlyfrom the control computer's memory and saves them for display on a user ter-minal or tor output to a plotting device or mainframe computer. A programsimilar to MINDSbut less sophisticated is described in reference 5. MINDSmakes extensive use of the 8087 math co-processor and occupies about 16 kilo-bytes of RAM. The remaining 36 kilobytes of memory are available for theactual control algorithm software and other user programs.

Interface Hardware

The patch panel, which was shown in figure 4, is the heart of the CIM unitinterface hardware. It consists of two 34x24 connection panels joined togetherand divided into groups of three connections (fig. 8). This allows high, low,and shield connections for each signal to be passed through the patch panel.The signals available at the patch panel include the trunk lines and outputsto the data recorders from the base connectors, all the analog and discreteI/0 signals from the controls computer, the buffer amplifier inputs and out-puts, and the status light inputs and switch outputs from the display panel.Thus, any signal at the base connectors can be made available to the controlsmicrocomputer with or without buffering, the lights and switches on the displaycan be tied to the control discrete I/0 if desired, or any signal can be fedto an external device such as a chart recorder. In addition to the signalsmentioned, the patch panel also has +5 volt, +10 volt, and ground areas fortesting, and jumper areas A1-A4 for signals which need to go to more than oneplace.

The base connectors, located in the bottom of the CIM unit are shown infigure 9. These connectors are each configured to carry 10 signal pairs withshield. The 128 trunk line signals which are used to interface to an engineor simulation are brought through these connectors along with twenty signalsreserved for interfacing with external data recording devices such as chartrecorders.

The final components of the interface hardware are the buffer amplifiers.The operational amplifiers chosen are particularly good for stable driving ofcapacitive loads such as trunk line cabling. The inputs and outputs of theseamplifiers are brought to the patch panel so that any signal being input to oroutput from the CIM unit can be buffered if desired. A diagram of the circuitincorporating these buffer amplifiers can be found in figure 10.

Monitoring Hardware

All the signals going to and coming from the CIM unit and all the signalsyoiny to and coming from the controls microcomputer are brought to the switch-iny matrix (fig. ii). The switch matrix acts as a 256 differential input,single differential output multiplexer. To reduce commonmode capacitance andleakage current effects, a two stage configuration is used (fig. 12}. Thefirst staye is composed of sixteen groups of solid-state switches, each groupnavin 9 sixteen inputs and one output (fig. 13). The second stage accepts thesixteen ouputs of the first staye and produces the final output of the system.Eiyht address lines allow selection of any one of 256 channels. Four addresslines yo to each stage of the switch matrix. The four least significantaddress lines are tied to each of the sixteen groups of switches in the firststage and the four most significant address lines are tied to the single groupof switches in the second stage.

CMOSanaloy switches were chosen to implement the switch matrix. Thespecific analog switches chosen exhibit low on impedance, have overvoltage andlatchup protection, and low leakage current. The inputs to the switches areTTL compatible. A CMOS multiplexer(UI on fig. 13_ was chosen to drive theinputs to the switches. These multiplexershave low power consumptionandwhen driven from a 5 volt power supply,satisfythe input requirementsot theanalog switches. Also, their rise time is slowerthan a compatableTTL partwMich in turn reducesthe chance of high frequencynoise coupling into theanaloy signalsbeing multiplexed.

In desiyninythe switchmatrix,effortswere made to minimize crosstaIKbetweenchannels and to minimize loadingof the signalsbeing multiplexed. Inthis way , the switchmatrix is close to invisibleto the signals. To I_elpminimizecrosstalkbetweenchannelsduring switching,an open channel isselectedbetweenselectedchannelsto insurethat the deselectedchannelturns

completelyoff before the selectedchannelstarts to turn on. Also, thetwistedpair, shieldedcables used to carry the si9nalsthroughthe CIM unitare Lied directly to the backplaneof the switchmatrix to minimizecrosstaIKand noise (fig. 9).

The output of the switching matrix is fed to the scaling circuit shown intiyure 14. This circuit uses a very high input impedance instrumentationamplitier to prevent loading of the input signal. This amplifier is configuredtor unity gain. Its output is used as the reference input to a 14-bit multi-plying digital to analog converter (MDAC). The MDACthen multiplies the inputsiynal by one or a fraction thereof and feeds this signal to a 4 1/2 digit,digital voltmeter (DVM) located on the CIM Unit display panel. This causesthe voltage on the DVMto appear as volts or, when multiplied by the appro-priate fraction, as engineering units. The DVMdecimal point, which iscontrolled externally to the DVM, is then placed to cause the display toappear as the proper units.

A switch is provided on the CIM unit display panel (fig. 15) to allow theuser to select whether volts or engineering units should be displayed on theDV_t. This switch also lights'the appropriate half of its panel face to intormthe user which units have been selected.

A keyboard on the display panel allows the user to input to the monitoringsystem. This keyboard has eighteen keys: ten keys for the numbers 0-9 and theother eight for functions. The numeric keys are used to select the channelnumber which the user wishes to monitor. The SET key then enters this channelnumber into the monitoring system. Keys are provided to increment and decre-ment the channel number, and also to switch back to the previously selectedchannel. These allow rapid scanning of channels. A shift key is provided toallow each of the keys to take on two functions if desired. Finally, themonitoring system reset is also at the keyboard. Two keys, labeled A and Bpresently nave no defined function.

In addition to the DVMthere are three other displays on the CIM unit dis-play panel. A numeric display is provided to inform the user which channelhas been selected. This display consists of four single-digit seven-segmentLED displays grouped together. These accept Binary-Coded-Decimal (BCD) input.The second display is a 40 character, 5x7 dot matrix, vacuum flourescent alpna-numerlc display. It accepts either parallel or serial ASCII data and isdesigned to be interfaced directly to a microprocessor. Examples of its useare in figure 15 and 16. The third display is a five digit alphanumericdisplay which is not used at present.

Also on the display panel are the input switches and the indicator lights(fig. 15). The switches are alternate action, double-pole switches. Whenactivated they close across the inputs brought to them and also light theirfront panel face. The indicator lights have the same panel face as theswitches. Tney are lighted by closing across their inputs. In addition, thereare 16 spares which can be used as either lights or switches.

Monitoring System Microcomputer

All the monitoring functions are controlled by a microprocessor-basedsystem. Tnls system consists of a single board computer, custom designed andfabricated at NASALewis, which is based on the 8085 microprocessor (fig. 171.Tnis board contains the microprocessor, 8 kilobytes of eraseable, programmable,read only memory (EPROM), 1 kilobyte of RandomAccess Memory (RAM), a keyboard-display controller, 2 parallel port chips, and all the necessary buffering andinterface hardware. A block diagram showing the major parts of this micro-computer can be found in figure 18. Further information on the 8085 and itsperipherals can be found in reference 5. The circuit diagram for the 8085microprocessor and its address, data and control bus buffers is shown infigure 19. The 8085 microprocessor has its lower eight address lines and theelght data lines multiplexed onto the same pins (ADO-7). The two 8212input/output ports shown in figure 19 are used to demultiplex these lines andalso to buffer the address lines. The data lines require bidirectionalbuffers. Two 8216 bidirectional bus drivers are used for this purpose withthe RD/ line controIlin 9 the data direction. A third 8216 is used to bufferthe control bus signals. The buffered address, data, and control signals areused throughout the monitoring system microcomputer. In addition, thesesignals are also bussed across the backplane of the digital chassis. Thismakes it possible to expand the capabilities of the microcomputer, if neces-sary, by adding cards to the digital chassis.

The memory and all of the peripherals in the monitoring system microcom-puter are memory mapped, that is, they are addressed as if they were locationsin memory. Several 3205 one-out-of-eight decoders are used with the addressbus to generate the chip select signals for the memories and peripherals.This insures that each memory and peripheral chip has an unique address. Amap or tllese addresses is shown in figure 20.

Two types of memory are used in this microcomputer. The first type isErasable, Programmable, Read Only Memory or EPROM. This memory retains itsdata when the power is turned off and so is used to store the microcomputerprogram. Two kilobyte, ultraviolet erasable 2716 memory chips are used forthis purpose (fi_. 21). However, these memories have an access time slowerthan the 8085 microprocessor which is reading data from them. A wait-stategenerator circuit, shown schematically in figure 22, is used to compensate forthese slower memories. It halts the 8085 for one machine cyc|e whenever oneot the 2716 EPROMchips is selected. The second type of memory used is RandomAccess Memory or RAM. This memory is volatile, that is it does not hold itsdata when the power is turned off. Thus, this memory is used for temporarydata storage while the program is running. A pair of 2114 static RAMSareused (fig. 21). These 1024x4 bit memories are fast enough that no wait-state_enerator circuitry is required.

The display panel Keyboard and channel display interface to the micro-computer through the 8279-5 keyboard/display controller (fig. 23). This con-troller accepts data from the 8085 processor for output to the channel displayand supplles data to the 8085 as to which key, if any, has been pressed, itcontrols all scanning and encoding/decoding functions required for this inter-face. Parallel I/0 ports are needed to provide the scale factor to the multi-plying DAC, the address to the switch matrix and to drive the DVMdecimalpoints. In addltion, one I/0 line is used to read the Engineering Units/Voltsswitch on the display panel. Two 8255 programmable peripheral interface cllipsare used for these purposes (fig. 23). Each has three 8-bit parallel ports.Two ports are used for the 15-bit MDACscale factor, one port is used for the8-bit switch matrix address, one port is used for the 4 bit DVMdecimal pointdrivers and one line is used to sense the Engineering Units/Volts switch. Tiledecimal point drivers are buffered to withstand the high off-voltage of theI)VMdecimal points.

The 5x7 dot matrix alphanumeric display interfaces directly to the 8085address, data, and control buses (fig. 24). Data is written to tile displayand status read from the display as if it were an 8085 peripheral. This makesinterfacing to the display very straightforward.

Monitoring System Software

The software for the monitoring system microcomputer is divided into sevenfunctional modules called CMMAIN, CIMINT, CIMIN, ClMCMP, ClMEUT, CIMOUT, andClMDAT. The organization of these modules is shown in figure 25.

The monitoring software executive, CMMAIN,is jumped to whenever the RESETbutton is pushed or the power turned on. It initializes the stack, calls theinitialization routine ClMINT, and then goes into a loop which calls CIMIN,CIMCMP,and CIMOUTcontinuously. A flow chart of CMMAINcan be found infigure 26.

CIMINT initializesall the monitoringsystem peripherals(fig. 27). Theseincludethe 8279 and 8255 chips, the displays,the switch matrix address,theMDAC scale factor,and the DVM decimalpoint placement. The routineoutputsan initializationmessage to the alphanumericdisplayduring this process.Wnen finished,it then outputs a messagerequestingthe user to select acnanne]for display.

The input routine, CIMIN, checks for input from either the EU/Volts switchor the display panel keyboard (fig. 28). It stores the input and sets a flayindicating there has been input.

CIMCMPdetermines what action to take depending on what the user input was.It then supplies the appropriate outputs to the output routine (fig. 29}. Ifthe EU/volts switch has been changed, it fetches the new scale factor, decimalpoint placement, and message for the alphnumeric display from memory. If akey has been pressed, ClMCMPdetermines if it is a number or a function key.If it is a number, a flag is set telling the output routine to output thenumber to the channel display. If it is a function key, then the appropriatefunction is carried out. CIMEUTis the subroutine used by CIMCMPto fetch DVMdecimal point placement, alphanumeric display messages, and MDACscale factorsfrom memory (fig. 30). This data is then saved for output by the outputroutine. All of the data required by CIMEUTis contained in CIMDAT. The waythe data is set up in CIMDATis shown in figure 31.

The last subroutineis the output routine,CIMOUT. This routinetakes thedata suppliedby CIMCMP and outputs it to the alphanumericmessage display,the channelnumber display,the multiplyingDAC, the DVM decimalpoint drivers,and the switchmatrix (fig. 32). It outputscharactersto the messagedisplayfrom the addresssuppliedby CIMCMP until FF hex is encountered. Output tothe channeldisplay,the MDAC, the DVM decimalpoints,and the switchmatrixare throughthe peripheraldevicesmentionedin the hardwaresectionof thisreport.

At present, all the monitoring system software is contained in the first 4Kilobytes of the microcomputer memory. The code, consisting of the sixroutines, is contained in the first 2 kilobyte EPROM. The data in CIMDATisin the second 2 kilobyte EPROM. This was done so that the data, which isapplication specific, could be programmed for each application without changin 9the code. The data EPROMfor each application can then be plugged into themicrocomputer as required.

TESTINGAND VERIFICATION

All the hardware and software in the CIM unit has been thoroughly testedfor proper operation. The Controls Microcomputer has been used to run programsunder the control of CP/M-86. This verified correct operation of the micro-computer and also of the disk controller. The control I/0 boards have beentested and calibrated using routines written for that purpose. All signalrouting through the ClM unit has been verified as correct. The MonitoringSystem underwent three phases of testin 9 and verification. First, the moni-toring system hardware was exercised and debugged using an In Circuit Emulator(ICE-85). Next the software was executed with the hardware, again usingICE-85. Most recently the CIM unit has been used to evaluate an imp}ementationof the Multivariable Control for the Pratt and Whitney F-IO0 turbofan engine.The Control, Interface and Monitoring systems have all been used extensivelydurlng this evaluationand have performedproperly.

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DISCUSSION

The CIM unit has been designed to be user friendly. A sample user sessioncan be found in the Appendix. This is a typical session during the evaluationot the F-tO0 Multivariable control and demonstrates how the CIM unit interactswith the user. It also shows how the ClM unit functions as a research tool.

The ClM unit has also been designed to meet the needs of the future byproviding the flexibility to adapt to future needs and programs. Possibleexpansions to the CIM unit include: (i) Dynamic Data Taking ability, (2} aSerial Data Interface, (3) Line Filters, (4) Audio (Voice) Output. The dynamlcdata taking system might consist of a large memory and the software to scanall the data passing through the CIM unit during a transient and store it.T_Je serial data link could then be used to transfer the transient data to a

inalntrame computer for massaging and plotting. Filters could become necessaryit the CIM unit were used in a noisy environment such as an engine test ceil.Audio and/or voice output would allow the CIM unit to warn the user if aproblem occured, such as exceeding a temperature or pressure limit. All ofthe electronics necessary to implement these features could be incorporatedinto the digital or analog electronics chassis already contained in the CIMunit.

Lastly, slnce the CIM unit design is processor independent, the ControlsMicrocomputer could be changed if desired. This allows future state-of-the-artmicroprocessors or systems such as distributed processors or multiple proces-sors to be exchanged for the present 8086 based system.

CONCLUSIONS

The Control, Interfaceand Monitoringunit has fulfilledall its designrequirements. It is being used successfullyat present,and providestheability to meet the needs of future programs.

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APPENDIX

The following is a step by step example of how the Monitoring System inthe CIM Unit would be used during the evaluation of a control program. A ter-minal with an RS-232 port should be connected to the serial port of the con-trols microcomputer. The terminal used for this example is shown in figure 3ot the report.

i. Turn the CIM Unit power on. This causes the Monitoring System to bereset. The Alphanumeric message display shows

"Initializing CIM Unit"

All the segments on the channel display are lighted to ensure that they areworking properly. The channel display shows

8888

There is a delay of about four seconds and then the channel display is cleared.The Alphanumeric display then prompts the user with:

"Select a Channel"

At this point the monitoring system is ready for operation.

2. Next, the controls microcomputer must be initialized. A CP/M-86system disk with the control program on it is placed in floppy diskdrive A. The RESETbutton on the iSBC 660 chassis is pushed. Theterminal prints:

BOOTINGCP/M-86CP/M-86 VERSION1.0 DOUBLEDENSITYSEGMENTADDRESS= 0040LAST OFFSET: 2975SYSTEMGENERATED2 June 81A>

The controls microcomputer is now ready for operation. To run the controlprogram the user must type in the nameof the program. For the FIO0 MVCtheuser would type:

A> MVC

The control program is now running.

3. The monitoring system can now be used to interrogate the control'sI/0 signals. The user must key in the desired channel number. Forinstance, if the user wants to monitor channel three, the keys '3'and 'SET' are pressed. The channel display now shows:

3

10

and the message display shows:

'OUTPUTIN VOLTS'

The DVM will display the signal on channel three in volts.

If the user wants to see channel three in engineering units, the EU/VOLTSswitch is pressed. This causes the DVM to display channel three in the appro-priate engineering units and the alphanumeric display to identlfy what thoseunits are. For the FIO0 MVC, the messaye display would show:

"AJ NOZZLE AREA SQ. FT."

and tile OVMwould display the nozzle area in square feet.

To change channels, say to channel eleven, the user would push the keys 'i','i' and SET. The channel display would now show

11

and the DVM and message display would show the engineering units and a descrip-tion ot those units respectively.

At this point, pressing the Previous Channel key would cause the monitoringsystem to switch back to channel three since this was the channel selectedjust before the present channel. If the user pushed Scan Up instead, channeltwelve would be displayed or pushing Scan Down would cause channel ten to bedisplayed.

At any time, the monitorlng system can be restarted by pushiny the 'RST' keyon the display panel. The controls microcomputer is restarted by pushing theRESET button on the front of the iSBC 660 chassis.

11

REFERENCES

1. Szuch, Jonn R.; et al.: FIO0 Multivariable Control Synthesis Program-Evaluation of a MultivariaDle Control Using a Real-Time Engine Simula-tion. NASATP-I056, Oct. 1977.

2. Lehtineh, F.K.B.; et. al.: FIO0 Multivariable Control SynthesisProgram - Results of Engine Altitude Tests. NASATMS-83367, 1983.

3. Soeder, James F.: FIO0 Multivariable Control Synthesis Program - Com-puter Implementation of the Multivariable Control Algorithm. NASATP-2122°

4. Arpasi, D. J.; Zeller, J. R.; and Batterton, P. G.: A General PurposeDigital System for On-Line Control of Air Breathing Propulsion Systems.NASATM X-2168, February 1971.

5. MCS-80/85 Family User's Manual. Number 21506-001, Intel Corporation,Oct. 1979.

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Figurei. - 810Bminicomputerandsignalprocessingunit.

Tohybridenginesimulationor actualengine

Floppy_ controldisks module monitormodule(8086pP) (8085pP)

UUserterminal(RS232)

Figure2. - CIMUnitorganization.

Figure3o- CIMunit andterminal.

32 64

lights - panel nI _ DiscreteControl

Buer O,m,cro-AMPS / 32/ I_''_c°mputer

I Alphanumeric

displa_/_13 CMOS

_ +5 switch _ Todata

8085 = AG_D matrix

computer /, Base _" recorders8" AI7 128 I 1z81connection

"'/ "'/'I p Tohybrid

15 AmpI Channel / E C-'II display

Figure4. - ClMUnit blockdiagram.

Figure5. - ISBC86/12asingleboardcomputer.

Figure6. - ISBC600multibuschassis.

32Differential 24DiscreteFloppydisks inputs inputs

UA/D

8 Analog 4 Analog 32Discreteoutputs board outputs outputs

iSle

86/12AMicro-controller

Multibus

Figure7. - Controlmicrocomputerhardwareorganization.

ABC D E F G H J K L M N P Q R STU V W X Y Z AA BB CC DD EE FF GG HH JJ KK LL MM NN PP QQ RR SS IT UU VV WW XX YY ZZ

1

2

3

4

5

6

7 N N

8 Switches Discrete Lamp Discrete Mux Inputs Trunks Trunks Buffer Amps DACS Data 0 0

9 inputs drivers out out in recorders T T

10 0-31 0-31 32 - 63 64 - 95 96 - 127 0-31 0-31 0-31

11 0- 31 0-31 0-31 0- 31 32 - 63 U U

12 S S

13 E E

14 D D

15

16

17

18

19

20

21

22

2324

25

26

27

2829

30

31

32

33+10V Al A2 ~ffi2a~,~ A3 A4 +5V

34

Figure 8. - CIM unit patch panel layout.

Figure9. - Insidebackviewof ClAAunit.

+15V

R1 Cl

4.7K __.01pf6 +

, =Vout

-15V =_r-"v°utVin- _J.. C2

: m.oi.f

Figure10. - Bufferamplifiercircuit.

Figure11.- Switchmatrix.

Switchmatrixoutput

+ -

If•t- -

Signalout

t3_2 Switch_1 group_0 16

Signalinputs0 l 15

+ - + - + -

IJ::: ]Ay_A6_

A_dress_ i I11 . r

I+ - + - + -

Signal Signal SignalA3 out A3 out outA3A2 Switch A2 Switch A2 Switch_'I group AI group A]I groupA,0 0 AO 1 • • • AO 15

Signalinputs Signal inputs Signalinputs

0 l 15 0 1 +15 j +0_ l 15+ - + - + - + - + - _ + - + -

ffll Jl Ill il Illl [+ - + - + - _ + - + - + - + - _

Channel# 0 1 • • • 15 16 II • • • 31 240 241 • • • 255

Figure12.-Switchmatrixblockdiagram.

+SV

I.UI-MC14514

2. U2-U.9-ADI510

AO UI

zz[L'-ff-O- _

',J I10 [15!16113141112 91 15 161131411111219 15 1611311411111219 T5 lSF131141111219 ll5 1611_ 111111219 11516113141111210 10 1151611314111 1219 10

I' ' I

11 I : tl : , .- : _ , : _- ; _ , : : : : • : ; : : : -_ : : :

l ! '+ + + 2 + 3 4 5 6 + 7 8 9 - + I0 II 12 + 13 14 15

Signa{inputs

Figure13.- Switch matrixswitchgroup.

+I5V

1317

Vin+_ 18

__ 21REF 24

.vou,..... 2(REF U2 . AG,_23Vin-< GND

_ GNDMSB LSBi 15

Figure14.- Scalingcircuit.

Figure15. - CIM unit displaypanel.

(a)Todirectuser'scourseof action.

(b)Toidentifyunitsof I)VMreadout.

Figure16.- Examplesof alphanumericdisplayusage.

Figure17o- 8085singleboardcomputer.

8085A-2 I

lJ II III _u''ersI

,_t l_ lJ tl Iaiu_ lJ il 11Jl lJ lJ II ;; "__us II IIII I!ll Illl II lill IJII IIII

f 12 ,,I,I, II,l,I,,,,,, ! !t II ,J.'"--.

8K (programdata) (keyboard-display) PPI# 2 PPI#1 I I Future" I

(program) PA PB PA PB PC "9 "expanslon.,,J

_sKcalefactors) __1 II II L IIII_____scan , data"_ I_ _'- -- ....... ......

Keyboard t-] I_1 t 5x7 Dotmatrix J

IOt112131415I------I Char alphanumeric161718191AIBII I °'sp' display

ISlCIDIEIFIRI J I_,

_ ,ts IFigure18.- 8085Computerblockdiagram.

A 12(1)

6.144MHz +51/

At2(1) XI X 12 ._sTBVcc _T[-R A0

+51/ Vcc 14 i 2 _ AI2

AD_3 15 4 DI DO_2) R2 R I 16

"Reset" i, '_A5h6

_" CI 19A2 _Mo 8212 _'7-D ip' DS._ -_-15V

: 8%5A-2 "_'_._GND DS--I:_i._--_ +SV _-

Resetout 241 I14I

-- RST5.5 A8 71 11 S-IBVcc CL_R35RDY A9 22 5 _A 9

AI0 !2_ ? "----'"AI0All 9 4 4 _AI] Address

: _ A12 busA121 18A13 ..__.l,.. A138 RST&5 A14:27 20 A8 _A14

-- AI5 _ ; I 22 8212 _A15RST1.5 2 MD DS2 _,-+9,/

39 Hold CLK 130I0 ALE , +SV =_4

INTR IOIM _---- IAI66 Rl)

'----TRAP __ [__ DO0 Vcc DB0 3__Do

DI0 1

Vss _7DO1 DBI= 120 11 DII All Data

15 _ GND

+SV

_t62 DO0 Vcc DB0 _ DA

DI0 _ }

DO

_I_DO 31 "_I]_" 18 ll)A12isacomponentmounting _ DI3 DB_ 13 D7

17 dip plugwith partsasshown 15 DIE--"N C-_

_ 16 (`2)Resetbuttonwill beoff the GND__4 ,,--I I---- 15 board _"_---_ 35 • Cl • 14+SV6 • • 15 (,3)IndicatesboardlID pins 74LS00

i.e. 7, 8-Tie tollD I

7 • A12 • 12 _168 • • 11 Pinsland8

4 DI0 VCc DB0 _ .

DB1 6 lOIN-_- I7 DII AI9 _ Control

9 DI2 8216 DB2 _ I bus12 DI3 DB3

15__ L'S-_-7

DIEN GND =-I_Figure19.-8085Processorandbusbuffers.

0

EPROM

2000-

AUXEPROM

4000- RAM4400"

AUX RAM

50O0

6OO0

Peripheraldevices

7000Un-used

FFFFI

Figure20.- 8085Computermemorymap.

DoD1D2D3 Data

bus

Figure21.- 8085Computermemory.

CLK

ALE

+SV16

All 1

A12 2 AI O

AddresSbus__A13 3 A2 A20 1112 54 1A2_8 12131_"_ P_'I I _ P_1___,,,, 10'1"O_"J _ CKCLR Q _-_ CKVccA14 4ElI 3205 6 A22 A22-- 05 10 r--_- ..LI 74LS00 --- +5V_-_ D 12D GND Q 8 RDY To--- ' Fig.19A15______55F2 069 _ 74LS74 ---

+5V'_6 E-33 GRD Ol I _- 74LS30__l--g

ROM0

ROM1t

ROM2

ROM_ ToROM4ROM5 Fig.21ROM6ROMI

Figure22.-Waitstategenerator.

+SV

AI t 26

,A8 [ A0 Vcc 0A9

Address AI0 A1bus A13

AI5 3938

A3 37+5V 3, 8255A-5 ? _ MDAC

l A0 Vcc O0 3: 18-- 3: C 19 =-

At O] _( DB 3 2120 _

0213 _ +_0 21 PB[122

4_ _ A2 AI6 0312 _-

3205 04 IT-- 21 Vcc RL _ 2; _423 _-- -- RL _ 3_ Reset4 Ell Oc 10 RL

6 5 _ O_ 9 22 =" AI RL 2___,. -- _ _'_ PCO 14 _ EU/voItsswitch

14LS00 __ 6 _ GRD 07 Z___. 12 \ 8279-5 RL. _ 3..___-_

_L_8 14 ..L?

15 / Shi! _

_ DisplayC-S -_ I SL,

19) SL.

CLK SL _ +5VCLK

Fig.19 Reset _26

--RD R'DReset oAOA_ --A 0 Vcc Ii .m- }

W_ OA _ -- A1Switch

WR V_s OA _ _ PA_4 40 _ matrix

[_ 39 _. addressDO A4 7 :DI 3, 8255A-5 --

Data _" 3__j C _ 3bus D4 3]

D5 _ DB ? DVMD6 -- PB : decimal

2_ 3 i 161 . points

35 ._set

5 _ _8+5

_D

_7Figure23.- Keyboard-_ispbycontrollerandparallelI/0.

Tomicroprocessor^ i

f_AoA 1 RDWR DO...... D1

111II IIIIIIIII lEE3600-20-040

Alphanumericdisplay

Figure24.- Interfacetoalphanumericmessagedisplay.

CMMAIN I1

I I I II C'M'NTI I C'M'N C'MCMPI I C'MOUTI

I' CIMDAT IL ...... ..I

Figure25. - 8085Softwareorganization.

CMMAIN}

I Initializestack I

I CaI'CIMINTI

I CallCIMOUTJ

Figure26. - CMMAINblockdiagram.

CIMINT )

i ,o,,,_,,z_i C,ear_aooe,I ,8255#1and#2 display

I 'n"ia"zeJ /Oisplay"se,ect/8219 a channel"

l 'w'_"m°_r'xI ( ), address- OFFH RET

Resetalpha- Jnumericdisplay

Oisplay"initializing" /

MDACscalefactor - OFFFFH

_, .

J Clearbuffers Iandflags

1Figure27.- CIMINTBlockdiagram.

ClMIN

EU/volts Yes

switch SaveswitchvalueIchanged?

( R_r )

Keyboard YesSaveinputinput?

I

INFLG: 2 I!

RET ( RET )

Figure28.- ClMINBlockdiagram.

CIMCMP

EU/voltsswitchchanged_ Keyboardinput

ye,t_er

,0_wi:'_.Vo.ts -- _or_

I I /o,,o,a_,I Save[ ", Not,mp,ementedIClMEUT "output / digit

in volts" / Function ignore

(_ RET _ IMDACscale (RET _ ( RET _Jfactor - OFFFFHI

set <,/_Wh h_ Previouschannel

I Decimalp°int I , _functionJ ,I I ........ I Savepresent I- X.XXXX Savepresent _lncrem_., .

_' channelnumber I or I channelnumber_ RET ) _ _ decrement

L°adnew ] I Channel ! I L°adnew I

channel number number- channelnumberch. num. _+1

fJ ChecklimitsI

EU_ Voltsc,_ I (_._)( R_r )

Figure20. - ClMCMPBlockdiagram.

ClMEUT "_ ."

No

t

/Display //"invalid channel".

I Fetchdecimalpointplacement ] ( RET _t

I Fetchvariable Inameandunitsf

I FetchMDAC Iscalefactort

Figure 30. - ClNEUTblockdiagram.

Tablename Contents

CHNDAT Defineswhichchannelsare valid

JT1 DecimalpointplacementdataJT2 MDACscalefactors

JT3 Channelvariablenames

JT4 Jumptableto units messagesJT5 Unitsmessages

Figure31.- ClMDATorganization.

..LMessagedisplay,,,_ofYPe _ MDACscale factor

I messageaddressI _ I scalefactorI I Channel

-_. ._isplay I lowbyte ,I Display I i \ ..

{character, _.._ii_?._ Yes _ /OutpUt/scalefactor

la_rr;_sent

_y decimalpoint

placement

tes _ ( RET )

. _Yes -' _ _No- ] Ign°reIdigit

(_. RET ) /Output +°,,I (.,,)1Addto address[channel

0

Figure32. - CIMOUTBlockdiagram.

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.

NASATM-834334. Title and Subtitle 5. Report Date

Design of a Microprocessor-Based Control, Interface June 1983and Monitoring (ClM) Unit for Turbine Engine Controls 6.Perform_ngOrganlzatlonCode

Research 505-34-027. Author(s) 8. Performing Organization Report No. :'

John C. DeLaat and James F. Soeder E-172510. Work Unit No.

9. Performing Organization Name and Address

National Aeronautics and Space Administration 11.ContractorGrantNo.Lewis Research CenterCl eve1and, 0hi o 44135 13.TypeofReport andPeriodCovered

12. Sponsoring Agency Name and AddressTechnical Memorandum

National Aeronautics and Space Administration 14. Sponsoring Agency CodeWashington, D.C. 20546

15. Supplementary Notes

16. Abstract

High speed minicomputers have been used in the past to implement advanced digitalcontrol algorithms for turbine engines. These minicomputers are typically largeand expensive. It is desirable for a number of reasons to use microprocessor-based systems for future controls research. They are relatively compact,inexpensive, and are representative of the hardware that would be used for actualengine-mounted controls. The Control, Interface, and Monitoring Unit (CIM) con-tains a microprocessor-based controls computer, necessary interface hardware anda system to monitor the control while it is running an engine. It is presentlybeing used to evaluate an advanced turbofan engine control algorithm.

17. Key Words (Suggested by Author(s)) 18. Distribution Statement

Turbine engine controls; Digital Unclassified - unlimitedcontrols; Microprocessors STARCategory Ol

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of pages 22. Price*

Unclassi fled Unclassified

*For sale by the National Technical Information Service, Springfield, Virginia 22161

Aerooau,,o.nOOEC,A.OU...CLO.,L111111Space Administration BOOK

Washington, D.C.20546

Official Business

Penaltyfor PrivateUse,$300 PostageandFeesPaidNationalAeronauticsand

"* SPaceAdministrltion

NASA.451

__ Iq3_TMAST£R: If Undeliverable(Sect_n ! 5sPostalManual)IX) Nut Return