Lightwave Communications manual Remote Calibration of the LDX-3232 Current Source, Gpib Command

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CA LI BRATION AND TR OUBLESHOOTING

Remote Calibration of the LDX-3232 Current Source

C H A P T E R 6

Remote Calibration of the LDX-3232 Current Source

The LDX-3232 Current Sources can be calibrated remotely via the GPIB Interface. All of the required calibration commands are listed in Table 4.1 in Chapter 4. The procedures below are general guidelines for writing a program to calibrate your instrument.

Note: The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger a service request. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register (via the *ESE command) and bit 5 of the Service Request Enable register (via the *SRE command). Service request (SRQ) handling depends on your GPIB hardware. Refer to your GPIB user's manual for details.

After a calibration value is entered, the *OPC? query may be used to determine when the calibration sequence is done. However, the *OPC, *WAI command, or *OPC? query should not be issued until after the expected calibration value is entered, or the system will "hang". This happens because the LDX-3232 Current Source will wait indefinitely for an input, yet not allow any input until the calibration is finished.

Current Source Calibration

There are three calibration adjustments required for the LDX-3232 Current Source. They are calibration of the constant current source for both bandwidths and ranges, calibration of the laser voltage measurement, and calibration of the constant light power (IPD) feedback circuits.

The LDX-3232 Current Source implements a two-point calibration for the current source. Two currents (approximately 20% and 80% of FS) are applied to a test load, and the resulting actual currents are fed back (by the user) to the current source. The laser current source calibration program uses the two sets of data to calculate new calibration constants. These calibration constants are used to set the actual current of the current source.

The following procedure is for calibrating each range of the current source. Start with the low range. After calibration is complete in this range, switch to the high range and repeat the procedure.

Configure the current source in the following manner for the laser current source calibration:

Function

State

GPIB COMMAND

LASER MODE

I (constant current low bandwidth)

LAS:MODE:ILBW

RANGE

Low (lowest per instrument model)

LAS:RAN x

LIMIT

90% of FS (full scale of range)

LAS:LIM:Ix

SETPOINT

80% of FS

LAS:LDI

04_06

LDX-3232

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Contents User’s Guide Page Table of Contents Remote Operation Command Reference Iv LDX-3232 List of Figures Vi LDX-3232 List of Tables Viii LDX-3232 General Safety Considerations Safety Information and the ManualSafety Marking Symbols Safety SymbolsWarranty Claims for Shipping Damage Comments, Suggestions, and Problems Description of the problemModel Number Serial Number End-User Name Company Phone Fax Xiv LDX-3232 Product Overview Introduction and SpecificationsGrounding Requirements Installing Your LDX-3232 High Compliance Current SourceAC Line Power Requirements Initial InspectionOperating the LDX-3232 Precision Current Source Gpib ConnectorTilt-Foot Adjustment Gpib AddressLDX-3232 Front View Maintenance Specifications Type Pulse Width Delay TTL13 µs 12 ms Description Model Number Available Options and AccessoriesPower On Sequence Applying Power to Your LDX-3232Power On State Connecting to the LaserCommon Laser Cathode Photodiode Anode Interlock Connections Back Panel LD ConnectorSetting the PD Bias Photodiode ConnectionsGrounding Considerations Operating a Laser in Constant Current I Mode Front Panel OperationDisplay Setting Up the Precision Current Source E R a T I O N Entering Photodiode Responsivity Values Operating a Laser in Constant Power P ModeMethod to calculate the responsivity is suggested below LDX-3232 Error Indicators Error IndicatorsError Indicators LDX-3232 Changing the Gpib Address Reading the Gpib AddressLDX-3232 Current Source Command Set Command SyntaxChanging Operation from Local to Remote OFF OLD NEW True False SET Reset LASLDI? LDX-3232 Command Path Structure Command PathsIEEE488.2 Command Commands LDX-3232 Frequently Used Commands NoneLIM Status Reporting Event and Condition RegistersOperation Complete Definition LDX-3232 Status Reporting Schematic Diagram Output Off Register Disabled 10 N/A Enabled 11 N/A 12 N/A 13 N/A 14 N/A 15 N/ALASerENABleOUTOFF nrf LASerENABleOUTOFF? Error Messages Command Timing and CompletionResponse Message Error Code ClassificationsMode Used to enter the laser voltage calibration mode Used to create a delay in the execution of furtherCommands Used to enter the laser current calibration modeReturns the value of the LAS conditions enable register Returns status of photodiode monitor power displayEnables Laser display to show parameter values Sets the enable register for Laser conditionsOr P optical power Used to return the optical power from monitorUsed to set the constant optical power setpoint, if Used to enable/disable the front panel modulation inputUsed to return the Laser setpoint tolerance value Returns the status of the Term commandPowered up Returns the elapsed time since the timer was last resetCommand Description Format LDX-3232 Device-Dependent CommandsDelay LDX-3232 Device-Dependent Command ReferenceERRors? LASerCALMDCalmd LAS Calpd LASerCALMD? Responsivity CAL PD parameter setting Syntax DiagramSelected. This procedure is outlined in Chapter LASerCALLDICalibration for that bandwidth LAS CAL LDV LASerCALLDI?LASerCALLDV LDI LAS CALTrue measured value. This procedure is outlined in Chapter LASerCALLDV?LASerCALMDI LAS CAL IPD LASerCALMDI?LASerCOND? MDILASerDEC LASDIS? LASerDISplayLASerDISplay? LAS DISLDI LASerDISplayLDILASerDISplayLDI? LasdisldiLASDISLDV? Voltage measurement Syntax DiagramLASerDISplayLDV LASerDISplayLDV?LAS DIS IPD LASerDISplayMDILASerDISplayMDI? LAS DIS MDILAS DIS MDP LASerDISplayMDPLASerDISplayMDP? PPDLAS DIS SET LASerDISplayPARAMLASerDISplaySET LAS DIS ParamLASerENABleCOND LASerDISplaySET?LASDISPLAYSET? LASerENABleCOND? BitLAS Enab Cond Lasenabevent LASerENABleEVEntAn nrf value whose sum represents the bits that are enabled Action enables the Laser status event register so thatLAS Enab EVE LASerENABleEVEnt?LASerENABleOUTOFF LAS Enab Outoff LASerENABleOUTOFF?LAS EVE LASerENABleEVEnt commandCommand while the condition status is constantly changing LASerEVEnt?Function for the Laser output LASerINCLAS LDI This measurement is updated approximately once every 600 msLASerLDI LASerLDI?LAS LDV LASerLDVLASerLDV? For LDV calibrationLAS LIM LASerLIMitI2LASerLIMitI2? Limit in use depends on the Laser output range selectionLASLIMI4? Displayed, and then releasing the SET switchLASerLIMitI4 LASerLIMitI4?LASerLIMitMDP LASerLIMitMDP?MDP LAS LIM LASerLIMitV? LASerLIMitVMDP P PD setpoint would be used LASerMDILASerMDI? MDI LAS IPDLASerMDLN LASerMDLN?LAS Mdln LASerMDP LASerMDP?MDP LAS LASerMODEIHBW LAS ModeLAS Mode Ihbw LASerMODE?Lasmodeilbw LAS Mode MDPLASerMODEILBW LASerMODEMDPLASerOUTput LASerOUTput?LAS OUT LASRAN? LASerRANgeLASerRANge? LAS RANLASerSETMDI? Where the response is the constant I setpoint value, in mA30 µA, for use in constant P mode with Calpd = LASerSETLDI?100 µA Where the response is the constand PPD setpoint, in mWLASerSETMDP? LASerSTEPLAS TOL LASerTOLerance commandLASerSTEP? LASerTOLeranceMES LASerTOLerance?MESsage Second is the time window, in secondsRADix MESsage?Means hexadecimal, and OCT means octal Term 0 command is sent or the LDX-3232 is powered offRADix? RADLDX-3232 was last powered up Time clock is independent of the Timer clockTime Seconds since the last TIMER? query was issued Since the last TIMER? query was issuedTimer Last TIMER? query is returnedSaving and Recalling from the Front Panel Functions and FeaturesSaving and Recalling Under Remote Operation Using the Laser Compliance Voltage AdjustmentLDX-3232 Rear Panel Using the LDX-3232 Current Source’s Trigger FunctionBNC Interlock Usage Example Modulating the Laser Current SourceModulating the Laser Current Source Functions and Features Calibration Overview Calibration and TroubleshootingDescription Manufacturer/Model Specification Recommended EquipmentDMM Current Limit Local Calibration of the LDX-3232 Current SourceCurrent Source Calibration RangeIPD Current Calibration IPD Setpoint Constant powerCAL PD Set equal to zeroSet to FS full scale of range Laser ModeLaser Forward Voltage Measurement Calibration 2000 mAGpib Command Remote Calibration of the LDX-3232 Current SourceLimit Lasldi nrf value command IPD Setpoint Function State Gpib Command Current source must be recalibrated Troubleshooting GuideGeneral EEPROM, Lllll will be displayed on the display the laserCommand Feature can be defeated via the Lasenableoutoff101 Response Message
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