Agilent Technologies 66lxxA manual Overview Of Application

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Application 7. Output Sequencing Without Computer Intervention

Overview Of Application

When characterizing devices, the DUT’s performance is measured over a range of power supply voltages. This test can be performed without computer intervention by using hardware signals from the measurement instrument to cause the power module to sequence to the next voltage in a preprogrammed List. By buffering these readings in the measurement instrument, the entire test can be executed without computer involvement. For characterizations that require long measurement times, the computer is free to do other tasks. For characterizations that must execute at hardware speeds, the computer is not involved and will not slow down the test loop.

In this example, the power module must apply 8 to 14 volts (in 13 0.5-volt increments) to an automotive engine sensor. The module varies the bias voltage to the engine sensor and the sensor’s output is measured to characterize its performance over the range of possible "battery voltages". The sensor output is measured by a DMM that has an internal buffer and stores each reading.

By combining Lists and trigger capabilities, the MPS can be used to address this application. The module can be programmed to use its triggering capabilities to the fullest extent. Each time the module executes the next step in its List and changes voltage, the module will generate an external trigger. The external trigger will cause the DMM, equipped with an external trigger input, to take and store a reading. The DMM, also equipped with a "Measurement Complete" output, sends its output trigger signal to the module to tell the module to go to its next List point. Effectively, the module and the DMM "handshake", so that the two function at hardware speeds without computer intervention.

When the test is complete, either device can signal the computer to get the data from the DMM. For the purpose of this example, the module will generate an SRQ when the last List point has been executed. This is indicated by the OPC (Operation Complete) bit in the status register.

Another detail that needs attention is timing. The DUT may require some settling time before the DMM is told to take a reading. The module’s dwell time can be used to do this. The STC (Step Complete) status signal indicates when the point has been executed and its dwell time has expired. The dwell time is programmed to be the engine sensor’s settling time. The external trigger is generated when STC is asserted. Thus, the DMM will not be triggered until the dwell time has expired and the sensor’s output has settled.

This type of self-paced test execution is useful in two situations. When the test must execute very fast, there is no time for the computer to be involved in each iteration of the test loop. Therefore, the test must execute without computer intervention. The second situation is when the test is very long. For example, if the measurement instrument took 1 minute to make each measurement, the test would take 13 minutes to execute. The computer is not used efficiently if it is idle while waiting for each measurement loop, so it would be best to have the computer executing another task. Without self-pacing, you would need to develop interrupt driven software that stops every 1 minute to take a reading. By letting the module and the DMM run on their own, code development is much simpler and computer resources are used more efficiently.

MPS Features Used

∙20-point voltage List.

∙Dwell time.

∙Trigger-paced Lists.

∙Generate an SRQ on a change in internal status.

∙Generate a trigger on a change in internal status.

∙Trigger in/out from MPS mainframe backplane TTL Trigger.

∙Trigger on a GPIB trigger command.

Application Programs 95

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Contents Agilent Part No Microfiche Part No Update April Programming GuideSafety Guidelines Contents Abor Status Reporting Synchronizing Power Module Output Changes Error MessagesDocumentation Summary IntroductionAbout This Guide External ReferencesAccessing Online Help VXIplug&play Power Products Instrument DriversDownloading and Installing the Driver Supported ApplicationsModule Gpib Address Gpib Capabilities Of The Power ModuleIntroduction To Programming Introduction To ScpiRST *IDN? *SRE Volt LEV Prot Curr Voltlev 8.0 Prot 8.8 CURR?Outpprotdel Traversing the Command Tree Effect of Optional HeadersVoltagelevel 7PROTECTION 8CURRENTLEVEL 3MODE List Outputprotectionclear STATUSOPERATIONCONDITION?OUTPUTPROTECTIONCLEARSTATUSOPERATIONCONDITION? Volttrig 7.5INIT*TRG Outp OFF*RCL 2OUTP onListening Formats SymbolNumerical Data Formats Talking Formats Suffixes and Multipliers Class Unit Unit with MultiplierSystem Considerations Assign @PM3TOError Handling Agilent Basic ControllersUsing the National Instruments Gpib Interface Sending the Command Volt 5 in Basic Sending the Command Volt 5 in CReceiving Data from the Module Receiving Module Data with BasicReceiving Module Data with C Language Dictionary IntroductionMeaning and Type Description Of Common CommandsCLS DescriptionESE Bit Configuration of Standard Event Status Enable RegisterESE ESR?OPC IDN?OPC? OPT? PSCRCL RCLRST SRE SAVSRE STB? Bit Configuration of Status Byte RegisterTRG WAI Description of Subsystem CommandsTST? AborSubsystem Tree Diagram Calibration Subsystem CalautoCalcurrlev Calauto 1 Calauto OnceCalcurr CalpassCalvolt CalsaveCalstat CalvoltlevCurr 500 MA Currlev CalvoltprotCurr CurrmodeCurrtrig CurrprotstatCurrprotstat OFF Currtrig 1200 MA CurrlevtrigListcoun Listcoun INF Init Initcont 1 Initcont onListcoun ListcurrLISTDWELPOIN? LISTCURRPOIN?Listdwel ListstepLISTVOLTPOIN? ListvoltListvolt 2.0,2.5,3.0 Listvolt MAX,2.5,MIN MEASCURR? MEASVOLT?Outp Outpstat ON,NORELAY OutpprotOutprelpol Outpprotcle Outpprotdel 75E-1Outprel NormOutpttltlink OutpttltOutpttlt 1 Outpttlt OFF Outpttltsour LinkSTATOPERCOND? STATOPER?STATOPEREVEN? StatoperenabStat Oper NTR 32 Stat Oper PTR StatpresSTATQUESCOND? STATQUES?STATQUESEVEN? Stat Ques COND?Trigger Subsystem SYSTERR?SYSTVERS? TrigTrigdel .25 Trigdel MAX Trig Trig IMMTrigdel TriglinkVoltmode VoltVoltlev Voltmode List Voltmode FIXVolttrig VOLTSENSSOUR?Volttrig 1200 MV Voltlevtrig Power Module Programming Parameters Link Parameter ListStatus Reporting Power Module Status StructureStatus Register Bit Configuration Operation Status GroupStatus Questionable Commands Query Bit Signal Bit Configurations of Status Registers MeaningQuestionable Status Group Power Module Status Model Standard Event Status GroupOutput Queue Status Byte RegisterLocation Of Event Handles Initial Conditions At Power On ExamplesSTATOPEREVEN?QUESEVEN? Statoperptr 5376ENABStatquesptr 18ENAB Statoperptr 1024NTR Statoperenab 1024*SRETrigger Subsystem Synchronizing Power Module Output ChangesModel of Fixed-Mode Trigger Operation Idle State Delaying StateInitiated State Trigger Status and Event Signals Model of List Mode Trigger OperationINITiateCONTinuous Command Output Change StateOutpttltsour List Subsystem Listcurr 2,3,12,15 Listvolt 3.0,3.25,3.5,3.75 Listdwel 10,10,25,40Automatically Repeating a List Triggering a ListTiming diagrams of Liststep Operation Scpi Command Completion DFI Discrete Fault Indicator SubsystemRI Remote Inhibit Subsystem System Error Messages Error MessagesPower Module Hardware Error Messages Standard Event Status Register Error Bits222 -223 -241 -310 -330 -350 -400 -410 -420 -430 Scpi Conformance Information Scpi Confirmed CommandsScpi Approved Commands Scpi VersionNon-SCPI Commands Application Programs Application 1. Sequencing Multiple Modules During Power Up Figure B1-1. Block Diagram of Application #1 Variations On This ImplementationFigure B1-2. Timing Diagram of Application #1 Enable Output Reset and Clear ModuleEnable Backplane TTL Trigger Drive Enable Response to TriggerImplementation Details How The MPS Implements The Solution MPS Set Up Figure B2-1. Block Diagram of Application #2 Enable Response to TTL Trigger When a CV-TO-CC Transition OccursEnable TTL Trigger Drive Start AT 15Application 3. Controlling Output Voltage Ramp Up at Turn On Figure B3-1. Simulating a Slow Voltage Ramp Generating the Desired Voltage Ramp for Application #3 Stop Voltage for Ramp Option BaseStart Voltage for Ramp SecondsApplication 4. Providing Time-Varying Voltages Figure B4-1. Voltage Waveform for Application #4Module set up Variations On This Implementation Enable Detection of OC Condition Enable OCPNo Delay Before Protection Occurs Enables Detection on Positive TRANSITION, I.EApplication 5. Providing Time-Varying Current Limiting Figure B5-1. Typical DUT Current vs. Time Implementation Details How The MPS Implements The Sequence Dwell Time Data GO to 12 V When TriggeredCurrent Limit Data SET to GET Current from ListApplication 6. Output Sequencing Paced by the Computer Nominal 12MPS Set Up Figure B6-1. Block Diagram of Application #6 To be Tested These are the BiasSupply Limit Conditions Number of Bias Supply Limit C0MBINATIONSReturn Overview Of Application Advantages/Benefits Of The MPS Solution Figure B7-1. Block Diagram of Application #7 Enable SRQ Interrupt When the Module Indicates SIC Step CompletedWhen IT Completes the LIST. OPC Generates SRO Enable Intr Identify Handler SubroutineSupplemental Information ‘ Conversion to Send Real Numbers Over the BUS CMD$ = Output on ‘ Enable OutputCMD$ = Initiate ‘ Enable Trigger to Start List CMD$ = Voltmode List ‘ SET to GET Voltage from ListCONDITION.DATA = Call Iooutputs SLOTO, CMDS, LWaiting for Trigger BIT 5 of the Operation Status Register Wend‘ Program N3.BAS ‘ Disable Auto Serial PollIf IBSTA% 0 then Goto ‘ AS Part of the Command String ‘ INSTRUMENT.NAME$ = SlotoIf IBSTA% 0 then Goto Selected AS a Trigger Source ‘ General Error HandlerStop Application #3 Controlling Voltage Ramp UP AT Turn on Dwell = ramptimeTo terminate the iooutputa Int error Char *badstring If error != EOl enabled for both read and write Strcatvlist, vpoint This is a generalized error checking routine Index IndexIndex Index Index Agilent Sales and Support Offices United States Latin AmericaManual Updates
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